Make sure your water tube that brings water up from the water pump isn’t corroded and leaking. This happens a lot in salt water boats.I was told just because the water is coming from the tell tale you need a certain minimum pressure to cool the outboard. I was told you don’t always get the pressure with the muffs and if you have a well that is your source for water it’s tough. Cut a 55 gallon plastic barrel with a drain on the side and it seems to be what the pros use.I would once again check and test the thermostat with a hot water test and confirm they are good. As we know new ones can be bad. Depending on the year last but not least do a computer diagnostic test . I appreciate your frustration and these steps have answered my problems. Best of luck.
Yep, I have an identical motor and same problem, but only in mossy lake OR when trolling at low RPMs (no-wake). My theory is that something along the way is reducing the water flow or pressure just enough that it gets slightly too hot. Usually my alarm goes off just after trolling through an approx. 1 mile no-wake river connecting two lakes. I shut it off for 2-3 mins and once I can get back to being able to run at higher RPMs it's fine.
I am feeling your pain right now. I have a Tohatsu 40 HP overheating and its not the pump or thermostat. No water at the thermostat or tell tail. Clean water jacket. Nor bugs in tell tail hose. I hate not solving this mystery. Thankfully there is a lot of advise here. I admire your persistence and attitude.
Well not everyone can just go buy a new outboard, besides if you take care of an older outboard it can last for years. I have a 21 year old Yamaha 2 stroke and it runs like new
My boat did the same thing. I changed out the thermostat, but it still ran hot when I tested it at home with the water "ears". I put it in the lake and it runs fine. I think it needs more water than the water ears can provide.
I ran my outboard in a 55 gallon barrel with about 10 gallons of vinegar & after running the outboard for several times with out overheating it. It slowly started cleaning all the gunk & crap that ha built up for years before I bought it. Vinegar worked for me . Good luck
I don't know if you have fixed it yet but remove the thermostat and put your garden hose there and turn it on full blast. It can help to clear the out flow. Water pump pressure is only 3-5 psi, it mostly moves volume of water through the jacket. A problem sometimes is bees (meat bees) make nests up inside these areas and you can't see it. Give it a try.
I’d suggest that as well. Had the same problem with my 50 hp Mercury at idle speeds. The over heat alarm kept going off even though I had a steady stream through the tell tale. Changed everything and then as a last result removed the thermostat again and back flushed through it with a garden hose. Problem solved.
I would use a temp gun to see if it is in fact over heating. Could be a faulty sensor. If not the. Pull the heads to get a better look at those passages. Also something could be clogging the pick up tube. Sometimes pieces of old impeller.
If it helps. Ask yourself if there have been any changes to the engine either you or someone else made. You were on the right track with the thermostat. Always check the old and new one in hot water. I’ve actually had bad new ones.
Just noticed that the description explains the problem. I have the exact same problem with the exact same motor, but realized that it really only happens when I idle a lot or troll in no-wake zones a lot. So I think mine is also due to not quite enough water/pressure going through the system. When running it at higher RPMs it seems to generate more water pressure are the problem doesn't occur.
Did you replace that thermostat? You should always be able to put your hand on top of the heads; even after/during running it at full speed for hours. If it feels anywhere near uncomfortable to leave your hand on there, then it IS overheating. 130°F max. 90-110 is normal. You can test the sensor by removing it and boiling it in some water. Put a multimeter on ohms across the wires. When the water approaches 130-ish, the circuit should close and give you a 0.00 reading. If it stays open (or it might say OL on the screen) after the water gets hot enough, then it is bad. If your temp sensor only has one wire, then measure between that wire and the metal base of the sensor. The only thing i didn't see you do, was pull off the water jacket gasket. If you don't want to damage it (cuz it's a lot of gasket scraping), then flush thru it with a hose, and make sure water comes out the other end. The water jacket cover is a thin space, and little shells will build up in there. However, if your thermostat comes out clean on the back of it, then it is unlikely. My best accessment? Test or replace that sensor. And trust how it feels to your hand; on both heads. But watch out for those spark plug wires. 🤣 (Hopefully this issue is long gone already)
sorry but a 90-110f reading is far to cold! horrible advice. if the t stat opens at 130, expect the heads to be 130-145f at the top! people incorrectly assume running cold is fine. its actually not... causes cold seizing and / or uneven piston/cylinder wear . id love to see where in the service manual it says 90f at idle is fine. i am an OMC mechanic and the range for almost all models is 125-160f at 900rpm. 160f is warm enough so you can keep your finger on the top of the head for about 2-3 seconds. being able to indefinitely hold your finger on the head is far too cold!
i literally just had the same issues with over heating only i found the issue, after back flushing and disassembling the entire disassemble-able parts of the water flows i found my issue was fragmented impeller peices located in the lower unit directly from the impeller pump to the feed tube the pump goes to up about 9inches into the pipe was an entire 6 peices of rubber blades now my engine ran with water during months of running before i just got sick of never going over 2400rpm, back flushing alone couldnt get the fragments out, i ended up taking a long wire and bent a tiny hook in the end and pulled each peice out one at a time. my engine seemed to run water only causing overheating when the water pressure sensor was plugged in, yes in. but this just goes to show that somtimes you really need to look hard for those peices as black in a black pipe can be mistakenly overlooked. hope this helped :)
Take it to the lake and use a thermal heat gun and see which head is getting hot . Also , big Yamaha motors don't like to run on a water hose very long . Test run it on the trailer at the boat ramp , alot of times it will cool better than on a water hose . After that , revisit your water pump and your water tube from the pump to the power head , it's copper and older motors they can have rot holes in them .
The poppet or relief valve just dumps excess water when you are turning higher rpms as the pump is putting more water into the block than required. Just a way to get rid of the extra water...it exits out the upper part of the mid section. Use an infra red temp gun to check wahat the actual head temps are.
You took off the only the first cover. The second cover reals all the passages for the cooling water around the cylinder head. That is where the gunk can be accumulated. You can take off the transmission and do a flush with mild acid and then run fresh water or do the right thing which is to take off the second cover, inspect and remove any gunk.
There is a little rubber piece in the lower unit, it’s meant to protect the exhaust heat from the water pump location. Make sure it is still in tact. If that little rubber piece is broken or not in place, there is your over heat issue
Actually take off both heads and water jacket covers to fully expose the cylinder jackets with all passages visible and clean them all up! Use a temp sensor to measure the results
I had a similar problem. Discovered it was the sensor gauge. My mechanic loaned me one to try and it worked. Found a new one on line and ordered it. $138 cost solved my problem.
I feel your pain, sir. You are my kinda guy, Why in the world would we take it to the shop when we can have all of this fun ourselves.? Please know that your suffering was not in vain. I just pulled my lower unit and checked my impeller........damn ! It was OK. Next I will check the thermostat and heat sensor, now that I know where to look, and then on to pulling off the head if I must. You were wise to get your wife the counter tops. I have been divorced twice because I am a rock head who is always right......even when it doesn't matter.. Thank you for your video and all your time and effort. Nice dog too.............
Maybe the fins from the last impeller went up into the water pick up tube on the motor up above the lower unit. Also it could be that you have some exhaust carbon stuck on the exhaust port before it gets to the propeller. I watched another video on this and those are my 2 answers that I have
1) you can test run a motor with tstats removed before buying anything. 2) there's a tons of water channels and passage ways in the block that can trap those little bits of propeller and debris. careful studying and blowing that out with an air gun is what i'd try. 3) gasket seals can be compromised (particularly after overheating) could have leaking exhaust back pressure counteracting your water flow pressure. 4) a new impeller, doesn't account for excessive wear left by the old one. always a chance pump may still be shy of it's original potential 5) maybe try to get an actual thermometer reading of your coolant to compare while your sensor going into warning?. . . i'm not a outboard specialist, but any technical thoughts thrown at you, when you're out of ideas, is a welcome thing.
Pull off both heads. There are large water passages that circle each cylinder. They are likely gunked or blocked up. But even before that. Your water flow seems weak. Did you change the whole water pump assembly? Impeller, wear plate and housing with liner? This may be an old motor, but they are super reliable and bulletproof. I have one two years newer that runs like a top. It’s had it’s fair share of issues, but it’s easy to fix and parts are plentiful.
With all due respect you should buy a engine service manual for your motor. I have one for my 200 hp Johnson and it has saved me a lot of money. It will give you a lot of information on exactly what the different parts do and save you a lot of time by not trying to remove components to find the issue.
Thank God for someone giving the best advice of all ! I'm a 40 year outboard tech and the first thing I learned that really made me successful was a service manual, go to troubleshooting and don't skip procedures until you find the fix .
Hey! There’s another guy and you need to pull the heads off and clean all the passages and holes that allow the water to flow- the other guys video was amazingly clear and ell done!
Just because you're poppet valve looks good does not mean it is good the spring has a tension on it that if it is not strong enough it will let water bypass the motor and go straight out through your drive you need to replace the spring on the pocket valve in order to make it work correctly the spring is set up at a certain tension so it will not let water leave the engine until there's enough pressure from the pump at a higher RPM at idle you will get a overheating alarm if the weight if the spring is loose
You have a low water pressure because there is a leak coming up the intake tube you need to remove the lower unit can you run a hose up inside the intake tube if you’re still not getting water pressure The midsection needs to be removed it might be corroded down there or the intake tube broken
check the tube from water pump to engine. had same proplem on my johnson. turned out to be a bunch of asian beetles maid a nest at motor end of tube. put slight air pressure at telltale. it blew all the crap out. put back together and woked fine. also check the seals at both ends of the tube
Happend to me an idiot ran my engine without water going to it and melted the water pump and sucked all that shit up the tub and clocked my engine. Ran a few times and then took my compressor out and blew some air through a water line and solved my issue! In this case you engine seems to be pumping water fine it’s the temperature sensor. Try replacing that.
Remove thermostat and run. Feel with your hand if the banks are even. If still getting overheat warning then there is internal block.remove the head and check with compessed air
I put in my gardenhose in where the thermostat is put in and flushed the SHIT out of my engine....IT worked and a lot of dirt that was locked up inside the channels in the bottom of the engine came out....i did this for a few minutes until clean water came out😁👍Then i put in a new thermostat and impeller,and so on....oh.dont forget to take your leg off before you do this tough😂👍
the hose connection is for flushing the engine not running the engine for more than a few minutes... 3 to 5 and then only at an idle. To test if the thermostat fixed the problem... back it into the lake and run it at about 3500... hopefully no alarm... I had to learn this lesson by calling my boat mechanic...
I have no connection to this guy, but if , in the future you need advice, try Dangar Stu. He has done many videos on outboards (his videos are use for demo purposes at come colleges in the US.) However, You problem was self induced sadly, but you done a great investigation. Stu is a marine engineer and is on youtube too. Good luck for the future.
It's November 2019 ! Got it fixed? Saw a guy put the impeller In wrong. Some folks put the impeller in the housing instead of directly to the shaft. Sometimes the orientation of the impeller flaps may have been turned wrong in the housing. It will still pump water but at a lower rate. Just sayin,,,,,,,,
Try putting on a Wisconsin sweatshirt and going back through the steps ... lol. I don't know, i'd check the heat sensor. Prob have to swap it out, but I have the identical motor and a similar sounding lake that I boat at lately.... Mine overheats every time after about 1-1.5 hours of running it at various speeds/RPMs. I think mine is likely something similar as mine makes pee pee but haven't checked further upstream from that. Usually I clean off the water intake plates and let it cool for a few minutes and it's good again..... also seems to happen far more often after trolling through about a mile no-wake zone.... so maybe the water pump in this one just doesn't pump enough at low RPMs
OK, well I am an OMC guy, but the cooling systems are pretty similar to the Yamahas....First, let me ask if both heads got hot during your last test on the flushette? Don't cut yourself down, I admire your thought processes...I'm sorry that you pulled those water covers off though, a lot of work, and it seems unlikely the problem is there...The water first flows to that exhaust cover, where the pressure relief valve is located...From there, the water flows to/through the heads and out of the engine. But, the water flows from the back of the heads out through the thermostats then down and out of that cylinder head cover you removed.....So again, it is very unlikely that the head cover was plugged causing an issue. Let's back up to last year when the problem began....Tell me more about what happened when the overheat alarm went off. You said you replaced the impeller, how did the old one look? Was it damaged? Were any of the impeller vanes broken off? If the old impeller "looked OK", there is probably another issue causing the overheating. Keep in mind that there is more to proper water pump operation than just the impeller. The impeller housing/liner must be properly sealed and not worn, is it possible that you crushed the water tube grommet when you reinstalled the gearcase after replacing the impeller? How long did the engine run OK this year before it started overheating again? That cooling telltale is at the beginning of the cooling circuit, so a good flow from the telltale doesn't mean the engine can't overheat. Again, I'm an OMC guy, so not that familiar with the Yamaha systems....But, that large bypass valve in the exhaust cover confuses me a bit...Was there a spring inside that cover/hose that fit over the plastic bypass valve? I'm thinking there should have been some sort of spring there. If not, water entering the exhaust cover (beginning of the cooling circuit) can just dump out of the cover and never circulate through the block....Kind of a cooling system "short circuit" that would surely cause the engine to overheat. The other thing to keep in mind is that running an engine on a flushette can be deceiving....The water pressure from the garden hose is acting like the water pump...So, it is best to test the engine on the boat in the water....I realize this is a pain, but it is important to realize how the pressurized garden hose can be confusing the issue here. So, I'm guessing that whatever was causing the engine to overheat last year is still an issue now. Does your boat have a water pressure gage? Just because water is flowing out of the telltale, does not mean you have sufficient water pressure to cool the engine properly.....Don't remove any more water covers and cylinder heads.....I suppose it is possible that you have a blown head gasket, but not likely....Doesn't look like the engine was overheated badly....Again, I will ask you to start the engine again (on the flushette is fine), wait a few minutes for the alarm, the shut it off and feel the top of both heads. If both heads feel hot, blown head gasket(s) are unlikely, which is a good thing.....I am thinking your problem has something to do with the water pump not working properly, like others have said. Reply back with as much info as possible, try to answer the questions I have asked also....Hopefully, a Yamaha guy will chime in....Again, please don't pull off any more covers or cylinder heads....Hopefully, your problem is a simpler one....
Kramden can we talk on the phone. I have a 1985 evinrude E90tlcos with some overheat issue and more. If you're willing I'll give you my number. Dave in Wisconsin
3 years late, but did you ever take off the lower unit and replace the impaler. Look up a water pump repair kit for your engine model and it will include new gaskets as well.
I thought my motor yam 40 was overheating, but it was actually a high pressure fuel injection pump.... I chased after cooling issues for 3 weeks, and finally investigated and learned that there was a defective fuel pump with that specific engine and year! The operation on the injection manifold was intense, but the service manager gave me the instructions and the fuel pump for free, other than stripping one bolt which was non essential... it was a perfect surgery and runs 100% now...
Mate I have issues with my Yamaha mechanic did everything he could no positive results could you please tell me what year was the engine if my fuel pump is faulty
@@bristopaulose7766 2004 if I recall.... an easy way to tell is if the motor slows down by itself and runs rouge... but no alarm goes off! I assumed my heat alarm did not work, but you can test that by taking out the rip cord when it is running. The HP FI pump is located deep in the Fuel injection manifold where the fuel sits and the float is. Yamaha is nice to work on and everything snaps in and out OK. Just don't mix up your bolts... some look very similar. Once you solve the problem it is a great motor. I think it was the first year that Yamaha introduced EFI to the Yam 40 too and there was a recall in the day.
@@bristopaulose7766 another good idea to test the temperature is to actually put a IR thermos on it and see what the actual temp is, then see what is normal and max is. Then you can rule out temp. My mechanic said those motors are designed to run very hot. Unless you burn yourself on it , it is not overheated he said. But the EFI problem manifested itself worse when the engine warmed up. This is what lead me to believe it was overheating. It would run fine when it was cold for the first 10 to even 45 minutes before acting up and rolling back on me right when I am out at sea. A secondary problem was I replaced the thermos which was faulty and stuck open. This lead the motor to run too cold and causes condensation and water to build up in the crankcase! I am luck it did not blow up that time. Since it is a smaller engine I used it for trolling thus the colder operation.
I removed the thermostat… leaving me with two channels to back flush with the garden hose ! The one pushed dark nasty water out of the center of the propeller… hopefully thats my problem !
I don't understand... if the t stats are put in a pot on the stove with water, just get a thermometer and watch to see when it opens. if it's faulty, won't open at all or open partially. also, why didn't you take the temp at the top of the heads to see what the running temp actually was to rule out the temp. switch/sensor? in addition, i believe there must be a pressure relief valve. if that's leaking, it will overheat the motor because water can't travel up the block to cool all cylinders.
Have you tried removing the gearbox and connecting the hose pipe to the water feed pipe and run the engine , this is so you have a direct water feed and let the engine run checking the exhaust plate between the cylinders which should stay cool enough to put your hands on ? Also remove the thermostat and water should be coming out as the water pressure from the hose pipe is acting like you are moving , if nothing is coming out then there's a blockage below the engine ?! There can be a build up of dirt or a broken water pump impeller pieces stuck in n the feed tube or the housing area below the engine !
Are you sure you did not install your impeller incorrectly sometimes they get get one of the ears turned around backwards or something doesn't go together quite right that impeller is tricky to get in there right if you don't know what you're doing
If it has a copper tube going up from the water pump look up in the mid shaft housing, look and see if the top fitting is still there or melted. I was fighting with same thing on my mariner turned out top mount for copper water tube was melted and engine wasnt getting water supply it needed. After i replaced top mount, problem solved.
it looks to me lke there is an impeller issue. It is very difficult to see if you are getting the correct pressure using the ears because of the added pressure the hose creates. I am not a mechanic . If the thermoststs are opening and closing and you have verified the sensors are in good shape(no shorts in the lines) then the impeller is the issue. Are you sure the lower unit is re-installed correctly? Have you checked to make sure the fins on the impeller are turing the direction? Just some ideas from a guy that has been through it!
2 OldFarts Homestead Almost I just replaced the impeller before trying everything else. I’m pretty sure I got it all back together properly. I ended up taking it in to the mechanic. I’m interested to see what he comes up with.
Sir, First off get rid of the muffs.They will not tell you if the water pump is working. You are using the water pressure from your water source.I use a plastic trash can,fill it with water after you put the lower unit in.I would pull the lower unit,and inspect the rubber grommet that connects the tube thus insuring that the water is going into the powerhead. Do you have a thermal image sensor? Point it at something and pull the trigger, it tells you the temperature. Now I read the solved notice. here I am trying to help and some wise guy says solved. Glad you have the issue solved, Ken
well we all learn somehow but brother id of dropped that t stat in some warm water and use a 1.00 cookin thermometer and check that baby at about 160 or 70
Look at the common denominators first. Such as, the most likely culprit... 1. Has the dog been out in the boat on the lake when this overheating happens? Because every time you ignored him/her and went to start the motor instead of throwing the toy, I literally saw him/her walk over and intentionally stand on the water hose.
Use a tub not a hose and when it over heats disconnect one temp sensor at a time to isolate which side make sure inside of block is not clogged with calcium
You can test the thermo sensor - put an ohms meter on the sensor - then drop it in water that is about 185f -200f - then shut the water off - it will go from resitance to open when the water cools - drop some ice cubes in it as needed - the cost about $40
Under head gasket there are things called deflectors that let water go around each cylinder. When those things go egg shaped they block the water from going around the cylinders. Replace them and it will run cool.
You need to take the cylinder head off as well on that bank that is getting hot you'll find that the water jackets around the cylinder wall will be blocked as well
I thought it was weird that the overheating horn did not sound, but the ramp rolled back as if it was over heated. It just coughed,,,, it did not puke.
I had the same problem too, it turn out that the new pump housing I installed to my motor didn't come with the rubber grommets for the pick up tube. I pulled the lower unit off again and compared the old pump housing to the new one and notice that there are two rubber grommet down inside the old pump housing for the pick up tube. Pullled them out and placed them into the new pump housing and reinstalled the lower unit. 😩👌
Man I’m really hoping this is the problem to mine i looked at the parts diagram online and I’m missing the rubber grommet that I guess keeps the copper pick up tube tight so hopefully that fixes it
@@travisgreen4451 It sucks having to drop the lower again and when you buy a so call complete parts kit for the water pump and there was no rubber grommets in it. I hope you still have the old water pump to remove the rubber grommets out of it, let me know if this resolved the problem with your motor. Good luck!
You have done plenty of work but here is two little things that I did not see in your investigations of the overheating. Take the thermostats out and ran a wire from the base of the thermostat house. Make sure that the passage is clear. The second item that I suggest, is drop the lower unit and at night time place a good strong flashlight in the brass/cooper pickup tube... the light should be inside the tube and no light should be coming out of tube specially at the end of the pipe..if you see break
give me a pressure gauge mounted on TOP{ of the engine* the highesr point; usually at #1 and a restrictor instead of a thermostat and ENOUGH water and should be good to go. The T-stats can cook a motor if they don't open and that starves the jackets of water. A poppet is SUPPOSED to maintain the water 'charge' on the motor and only open AFTER a certain pressure. Make sure there is NO crud letting the water out. You can verify by taking off the cover and running the motor with the poppet valve in place and just hold the spring against it as close to regular position as possible. if ANY water is getting past the valve, the powerhead may not fully 'cfill with water ALL THE WAY to the top (usually no.1 cy) Just one of those cylinders running dry will overheat one of those motors (their water pumps suck) You should get a pressure switch into the top of the motor(near or above no. 1 and it should always read more than 5 psi but at speed , it should read 10 or more (25 would be better so no crap gets a chance to make a home in there. This may be too late to help you but it may help someone. Good luck.
Is there any way to measure the temp of the water coming out? Could the sensor be bad? All I know is this needs to be fixed so you can get back to that Sugar Shack build!
Yb Family Farm tell-tale water was cold. Water coming out of the propeller was hot. In my very scientific temp test, the port head was hot but I could hold my hand on it for 1-2 seconds...starboard head was so hot it almost burned me. I think I’m in over my head. To the repair shop we go...
Did you find out what it was i’m going through same thing i changed water jacket gaskets water passages or good water flowing everywhere i don’t get it
Yes sir im watching what do you youre engine. Im getting stock about my engine its a same problem i check thermostats and everythings water gose on its a same problem.pls help more about it.
It’s your poppet valve or thermostat Change them both Thermostat control the temp flow The poppet valve controls the high rpm flow. Heating when running 🤦🏻♀️ cooling when idling says poppet valve to me.
My yamaha 200hp hpdi outboard was overheating went over everything . In the end it was that the poppet valve had corrosion under the plastic washer that goes inside the block it was making it to tight so the valve was sticking had to hook it out cleaned it up with a round file got all the corosion off as best i could put grease on it put back together and now it doent over heat any more
A flusher is not good for trouble shooting cooling system assuming water pump has been replaced run in a barrel with a pyrometer should 143 to 160 temp sesors are notoriously fail alot
Head is clogged the problem is inside the heads if you don't want to spend money just buy Muriatic acid and dropped inside through the thermostar leave there for 10 minutes acid has to be diluded 1:20
Make sure your water tube that brings water up from the water pump isn’t corroded and leaking. This happens a lot in salt water boats.I was told just because the water is coming from the tell tale you need a certain minimum pressure to cool the outboard. I was told you don’t always get the pressure with the muffs and if you have a well that is your source for water it’s tough. Cut a 55 gallon plastic barrel with a drain on the side and it seems to be what the pros use.I would once again check and test the thermostat with a hot water test and confirm they are good. As we know new ones can be bad. Depending on the year last but not least do a computer diagnostic test . I appreciate your frustration and these steps have answered my problems. Best of luck.
Yep, I have an identical motor and same problem, but only in mossy lake OR when trolling at low RPMs (no-wake). My theory is that something along the way is reducing the water flow or pressure just enough that it gets slightly too hot. Usually my alarm goes off just after trolling through an approx. 1 mile no-wake river connecting two lakes. I shut it off for 2-3 mins and once I can get back to being able to run at higher RPMs it's fine.
I am feeling your pain right now. I have a Tohatsu 40 HP overheating and its not the pump or thermostat. No water at the thermostat or tell tail. Clean water jacket. Nor bugs in tell tail hose. I hate not solving this mystery. Thankfully there is a lot of advise here. I admire your persistence and attitude.
What ended up being your issue? I also have a 1995 40 horse tohatsu 2 stroke doing the same thing. Just now diving into it
Rumor has it he eventually solved the problem by the tried and true method of buying another engine.
Well not everyone can just go buy a new outboard, besides if you take care of an older outboard it can last for years. I have a 21 year old Yamaha 2 stroke and it runs like new
My boat did the same thing. I changed out the thermostat, but it still ran hot when I tested it at home with the water "ears". I put it in the lake and it runs fine. I think it needs more water than the water ears can provide.
I ran my outboard in a 55 gallon barrel with about 10 gallons of vinegar & after running the outboard for several times with out overheating it. It slowly started cleaning all the gunk & crap that ha built up for years before I bought it. Vinegar worked for me . Good luck
Também já usei essa estratégia e resultou.
I don't know if you have fixed it yet but remove the thermostat and put your garden hose there and turn it on full blast. It can help to clear the out flow. Water pump pressure is only 3-5 psi, it mostly moves volume of water through the jacket. A problem sometimes is bees (meat bees) make nests up inside these areas and you can't see it. Give it a try.
I’d suggest that as well. Had the same problem with my 50 hp Mercury at idle speeds. The over heat alarm kept going off even though I had a steady stream through the tell tale. Changed everything and then as a last result removed the thermostat again and back flushed through it with a garden hose. Problem solved.
i agree with u. i have a experiance once.
You did great buddy.
Pulled that puppy to pieces and figured it out eventually. These are the best lessons.
I would use a temp gun to see if it is in fact over heating. Could be a faulty sensor. If not the. Pull the heads to get a better look at those passages. Also something could be clogging the pick up tube. Sometimes pieces of old impeller.
If it helps. Ask yourself if there have been any changes to the engine either you or someone else made. You were on the right track with the thermostat. Always check the old and new one in hot water. I’ve actually had bad new ones.
Just noticed that the description explains the problem. I have the exact same problem with the exact same motor, but realized that it really only happens when I idle a lot or troll in no-wake zones a lot. So I think mine is also due to not quite enough water/pressure going through the system. When running it at higher RPMs it seems to generate more water pressure are the problem doesn't occur.
Did you replace that thermostat? You should always be able to put your hand on top of the heads; even after/during running it at full speed for hours. If it feels anywhere near uncomfortable to leave your hand on there, then it IS overheating. 130°F max. 90-110 is normal.
You can test the sensor by removing it and boiling it in some water. Put a multimeter on ohms across the wires. When the water approaches 130-ish, the circuit should close and give you a 0.00 reading. If it stays open (or it might say OL on the screen) after the water gets hot enough, then it is bad. If your temp sensor only has one wire, then measure between that wire and the metal base of the sensor.
The only thing i didn't see you do, was pull off the water jacket gasket. If you don't want to damage it (cuz it's a lot of gasket scraping), then flush thru it with a hose, and make sure water comes out the other end. The water jacket cover is a thin space, and little shells will build up in there. However, if your thermostat comes out clean on the back of it, then it is unlikely.
My best accessment? Test or replace that sensor. And trust how it feels to your hand; on both heads. But watch out for those spark plug wires. 🤣
(Hopefully this issue is long gone already)
This is some helpful advice!
sorry but a 90-110f reading is far to cold! horrible advice. if the t stat opens at 130, expect the heads to be 130-145f at the top! people incorrectly assume running cold is fine. its actually not... causes cold seizing and / or uneven piston/cylinder wear . id love to see where in the service manual it says 90f at idle is fine. i am an OMC mechanic and the range for almost all models is 125-160f at 900rpm. 160f is warm enough so you can keep your finger on the top of the head for about 2-3 seconds. being able to indefinitely hold your finger on the head is far too cold!
i literally just had the same issues with over heating only i found the issue, after back flushing and disassembling the entire disassemble-able parts of the water flows i found my issue was fragmented impeller peices located in the lower unit directly from the impeller pump to the feed tube the pump goes to up about 9inches into the pipe was an entire 6 peices of rubber blades now my engine ran with water during months of running before i just got sick of never going over 2400rpm, back flushing alone couldnt get the fragments out, i ended up taking a long wire and bent a tiny hook in the end and pulled each peice out one at a time. my engine seemed to run water only causing overheating when the water pressure sensor was plugged in, yes in. but this just goes to show that somtimes you really need to look hard for those peices as black in a black pipe can be mistakenly overlooked. hope this helped :)
Take it to the lake and use a thermal heat gun and see which head is getting hot .
Also , big Yamaha motors don't like to run on a water hose very long . Test run it on the trailer at the boat ramp , alot of times it will cool better than on a water hose . After that , revisit your water pump and your water tube from the pump to the power head , it's copper and older motors they can have rot holes in them .
The poppet or relief valve just dumps excess water when you are turning higher rpms as the pump is putting more water into the block than required. Just a way to get rid of the extra water...it exits out the upper part of the mid section. Use an infra red temp gun to check wahat the actual head temps are.
You took off the only the first cover. The second cover reals all the passages for the cooling water around the cylinder head. That is where the gunk can be accumulated. You can take off the transmission and do a flush with mild acid and then run fresh water or do the right thing which is to take off the second cover, inspect and remove any gunk.
Jose Pereda yes exactly!! So close if he had Remove the second one he would’ve found his problem
Came here to post this. OP only got halfway to the water passages.
There is a little rubber piece in the lower unit, it’s meant to protect the exhaust heat from the water pump location. Make sure it is still in tact. If that little rubber piece is broken or not in place, there is your over heat issue
I’m having the same problem but with a Yamaha 30hp, will mines have the same rubber piece in there too?
Actually take off both heads and water jacket covers to fully expose the cylinder jackets with all passages visible and clean them all up! Use a temp sensor to measure the results
This will fix it..
A piece from the old water pump is logged in the block did you get all the old pieces from the old water pump?
Yeah man thats true try check it out
I had a similar problem. Discovered it was the sensor gauge. My mechanic loaned me one to try and it worked. Found a new one on line and ordered it. $138 cost solved my problem.
The gauge on the dash???
I feel your pain, sir. You are my kinda guy, Why in the world would we take it to the shop when we can have all of this fun ourselves.? Please know that your suffering was not in vain. I just pulled my lower unit and checked my impeller........damn ! It was OK. Next I will check the thermostat and heat sensor, now that I know where to look, and then on to pulling off the head if I must. You were wise to get your wife the counter tops. I have been divorced twice because I am a rock head who is always right......even when it doesn't matter.. Thank you for your video and all your time and effort. Nice dog too.............
always do what you want to do not what a wife wants you to do.....feel your pain on the overheating issue...
Maybe the fins from the last impeller went up into the water pick up tube on the motor up above the lower unit. Also it could be that you have some exhaust carbon stuck on the exhaust port before it gets to the propeller. I watched another video on this and those are my 2 answers that
I have
Love that mid-west determination. Never give up!
1) you can test run a motor with tstats removed before buying anything. 2) there's a tons of water channels and passage ways in the block that can trap those little bits of propeller and debris. careful studying and blowing that out with an air gun is what i'd try. 3) gasket seals can be compromised (particularly after overheating) could have leaking exhaust back pressure counteracting your water flow pressure. 4) a new impeller, doesn't account for excessive wear left by the old one. always a chance pump may still be shy of it's original potential 5) maybe try to get an actual thermometer reading of your coolant to compare while your sensor going into warning?. . . i'm not a outboard specialist, but any technical thoughts thrown at you, when you're out of ideas, is a welcome thing.
Rick Nuccitelli all good info. It ended up being an improperly installed water pump housing.
Music makes it hard to hear comments.
Pull off both heads. There are large water passages that circle each cylinder. They are likely gunked or blocked up. But even before that. Your water flow seems weak. Did you change the whole water pump assembly? Impeller, wear plate and housing with liner? This may be an old motor, but they are super reliable and bulletproof. I have one two years newer that runs like a top. It’s had it’s fair share of issues, but it’s easy to fix and parts are plentiful.
With all due respect you should buy a engine service manual for your motor. I have one for my 200 hp Johnson and it has saved me a lot of money. It will give you a lot of information on exactly what the different parts do and save you a lot of time by not trying to remove components to find the issue.
Thank God for someone giving the best advice of all ! I'm a 40 year outboard tech and the first thing I learned that really made me successful was a service manual, go to troubleshooting and don't skip procedures until you find the fix .
Hey! There’s another guy and you need to pull the heads off and clean all the passages and holes that allow the water to flow- the other guys video was amazingly clear and ell done!
Just because you're poppet valve looks good does not mean it is good the spring has a tension on it that if it is not strong enough it will let water bypass the motor and go straight out through your drive you need to replace the spring on the pocket valve in order to make it work correctly the spring is set up at a certain tension so it will not let water leave the engine until there's enough pressure from the pump at a higher RPM at idle you will get a overheating alarm if the weight if the spring is loose
You have a low water pressure because there is a leak coming up the intake tube you need to remove the lower unit can you run a hose up inside the intake tube if you’re still not getting water pressure The midsection needs to be removed it might be corroded down there or the intake tube broken
check the tube from water pump to engine. had same proplem on my johnson. turned out to be a bunch of asian beetles maid a nest at motor end of tube. put slight air pressure at telltale. it blew all the crap out. put back together and woked fine. also check the seals at both ends of the tube
Happend to me an idiot ran my engine without water going to it and melted the water pump and sucked all that shit up the tub and clocked my engine. Ran a few times and then took my compressor out and blew some air through a water line and solved my issue! In this case you engine seems to be pumping water fine it’s the temperature sensor. Try replacing that.
Remove thermostat and run. Feel with your hand if the banks are even. If still getting overheat warning then there is internal block.remove the head and check with compessed air
My goal here is not to screw it up too bad. Man that’s a mantra to live by 👍
I put in my gardenhose in where the thermostat is put in and flushed the SHIT out of my engine....IT worked and a lot of dirt that was locked up inside the channels in the bottom of the engine came out....i did this for a few minutes until clean water came out😁👍Then i put in a new thermostat and impeller,and so on....oh.dont forget to take your leg off before you do this tough😂👍
the hose connection is for flushing the engine not running the engine for more than a few minutes... 3 to 5 and then only at an idle. To test if the thermostat fixed the problem... back it into the lake and run it at about 3500... hopefully no alarm... I had to learn this lesson by calling my boat mechanic...
buddy,,,, ya gotta ace that music
Did you change the poppet valve? If your overheating even when the motor is peeing it's most likely the poppet valve.
I have no connection to this guy, but if , in the future you need advice, try Dangar Stu. He has done many videos on outboards (his videos are use for demo purposes at come colleges in the US.) However, You problem was self induced sadly, but you done a great investigation. Stu is a marine engineer and is on youtube too. Good luck for the future.
I will say the same for Stu,he is great at what he does and makes his videos easy to follow. Cheers from Australia.
It must be the tube water after the water pump
It's November 2019 ! Got it fixed? Saw a guy put the impeller In wrong. Some folks put the impeller in the housing instead of directly to the shaft. Sometimes the orientation of the impeller flaps may have been turned wrong in the housing. It will still pump water but at a lower rate. Just sayin,,,,,,,,
Test the heat sensor with an ohm meter for continuity
Try putting on a Wisconsin sweatshirt and going back through the steps ... lol. I don't know, i'd check the heat sensor. Prob have to swap it out, but I have the identical motor and a similar sounding lake that I boat at lately.... Mine overheats every time after about 1-1.5 hours of running it at various speeds/RPMs. I think mine is likely something similar as mine makes pee pee but haven't checked further upstream from that. Usually I clean off the water intake plates and let it cool for a few minutes and it's good again..... also seems to happen far more often after trolling through about a mile no-wake zone.... so maybe the water pump in this one just doesn't pump enough at low RPMs
Sorry posted above just before you mentioned trying the sensor. Mine usually smokes just a bit too when it's hot.
That a alarm noise you hear is your motors way of saying O M G you bought a pontoon boat !!
Mark Gray ...Deck Boat brother! The best of both worlds! Party on top, business on the bottom.
Looks like a deck boat judging from the hull. There are no pontoons.
OK, well I am an OMC guy, but the cooling systems are pretty similar to the Yamahas....First, let me ask if both heads got hot during your last test on the flushette? Don't cut yourself down, I admire your thought processes...I'm sorry that you pulled those water covers off though, a lot of work, and it seems unlikely the problem is there...The water first flows to that exhaust cover, where the pressure relief valve is located...From there, the water flows to/through the heads and out of the engine. But, the water flows from the back of the heads out through the thermostats then down and out of that cylinder head cover you removed.....So again, it is very unlikely that the head cover was plugged causing an issue. Let's back up to last year when the problem began....Tell me more about what happened when the overheat alarm went off. You said you replaced the impeller, how did the old one look? Was it damaged? Were any of the impeller vanes broken off? If the old impeller "looked OK", there is probably another issue causing the overheating. Keep in mind that there is more to proper water pump operation than just the impeller. The impeller housing/liner must be properly sealed and not worn, is it possible that you crushed the water tube grommet when you reinstalled the gearcase after replacing the impeller? How long did the engine run OK this year before it started overheating again? That cooling telltale is at the beginning of the cooling circuit, so a good flow from the telltale doesn't mean the engine can't overheat. Again, I'm an OMC guy, so not that familiar with the Yamaha systems....But, that large bypass valve in the exhaust cover confuses me a bit...Was there a spring inside that cover/hose that fit over the plastic bypass valve? I'm thinking there should have been some sort of spring there. If not, water entering the exhaust cover (beginning of the cooling circuit) can just dump out of the cover and never circulate through the block....Kind of a cooling system "short circuit" that would surely cause the engine to overheat. The other thing to keep in mind is that running an engine on a flushette can be deceiving....The water pressure from the garden hose is acting like the water pump...So, it is best to test the engine on the boat in the water....I realize this is a pain, but it is important to realize how the pressurized garden hose can be confusing the issue here. So, I'm guessing that whatever was causing the engine to overheat last year is still an issue now. Does your boat have a water pressure gage? Just because water is flowing out of the telltale, does not mean you have sufficient water pressure to cool the engine properly.....Don't remove any more water covers and cylinder heads.....I suppose it is possible that you have a blown head gasket, but not likely....Doesn't look like the engine was overheated badly....Again, I will ask you to start the engine again (on the flushette is fine), wait a few minutes for the alarm, the shut it off and feel the top of both heads. If both heads feel hot, blown head gasket(s) are unlikely, which is a good thing.....I am thinking your problem has something to do with the water pump not working properly, like others have said. Reply back with as much info as possible, try to answer the questions I have asked also....Hopefully, a Yamaha guy will chime in....Again, please don't pull off any more covers or cylinder heads....Hopefully, your problem is a simpler one....
It turned out to be that I bent a metal tab on the impeller when I replaced it. It was pushing water...just not enough.
Cool, I'm glad the solution was relatively simple...
Kramden can we talk on the phone. I have a 1985 evinrude E90tlcos with some overheat issue and more. If you're willing I'll give you my number. Dave in Wisconsin
@@daveg2199 Dave, would be glad to help if I can...Give me your number and a good time to call...Don
That's great. Thank you. My evenings are best between 8 and 10 p.m. Central standard Time or Sunday afternoons my number is 414-507-7843
3 years late, but did you ever take off the lower unit and replace the impaler. Look up a water pump repair kit for your engine model and it will include new gaskets as well.
I thought my motor yam 40 was overheating, but it was actually a high pressure fuel injection pump.... I chased after cooling issues for 3 weeks, and finally investigated and learned that there was a defective fuel pump with that specific engine and year! The operation on the injection manifold was intense, but the service manager gave me the instructions and the fuel pump for free, other than stripping one bolt which was non essential... it was a perfect surgery and runs 100% now...
Mate I have issues with my Yamaha mechanic did everything he could no positive results could you please tell me what year was the engine if my fuel pump is faulty
@@bristopaulose7766 2004 if I recall.... an easy way to tell is if the motor slows down by itself and runs rouge... but no alarm goes off! I assumed my heat alarm did not work, but you can test that by taking out the rip cord when it is running. The HP FI pump is located deep in the Fuel injection manifold where the fuel sits and the float is. Yamaha is nice to work on and everything snaps in and out OK. Just don't mix up your bolts... some look very similar. Once you solve the problem it is a great motor. I think it was the first year that Yamaha introduced EFI to the Yam 40 too and there was a recall in the day.
@@bristopaulose7766 another good idea to test the temperature is to actually put a IR thermos on it and see what the actual temp is, then see what is normal and max is. Then you can rule out temp. My mechanic said those motors are designed to run very hot. Unless you burn yourself on it , it is not overheated he said. But the EFI problem manifested itself worse when the engine warmed up. This is what lead me to believe it was overheating. It would run fine when it was cold for the first 10 to even 45 minutes before acting up and rolling back on me right when I am out at sea. A secondary problem was I replaced the thermos which was faulty and stuck open. This lead the motor to run too cold and causes condensation and water to build up in the crankcase! I am luck it did not blow up that time. Since it is a smaller engine I used it for trolling thus the colder operation.
You boat was codeing (hot water temp)
I think people should always have a temp gauge as well.
I removed the thermostat… leaving me with two channels to back flush with the garden hose ! The one pushed dark nasty water out of the center of the propeller… hopefully thats my problem !
I don't understand... if the t stats are put in a pot on the stove with water, just get a thermometer and watch to see when it opens. if it's faulty, won't open at all or open partially. also, why didn't you take the temp at the top of the heads to see what the running temp actually was to rule out the temp. switch/sensor? in addition, i believe there must be a pressure relief valve. if that's leaking, it will overheat the motor because water can't travel up the block to cool all cylinders.
Have you tried removing the gearbox and connecting the hose pipe to the water feed pipe and run the engine , this is so you have a direct water feed and let the engine run checking the exhaust plate between the cylinders which should stay cool enough to put your hands on ? Also remove the thermostat and water should be coming out as the water pressure from the hose pipe is acting like you are moving , if nothing is coming out then there's a blockage below the engine ?! There can be a build up of dirt or a broken water pump impeller pieces stuck in n the feed tube or the housing area below the engine !
Are you sure you did not install your impeller incorrectly sometimes they get get one of the ears turned around backwards or something doesn't go together quite right that impeller is tricky to get in there right if you don't know what you're doing
You video helped me get though the crisis with some good laughter.
Some of these motors have dual thermostats and I was watching the video and it looks like there's a thermostat housing on the other head also.
Chump Change Outdoors there is. One for each bank of cylinders. I have a motor two years newer than this one. It looks exactly the same.
I would checked the water passages behind the head gasket next. That is an old engine it would not hurt the have new head gaskets anyway.
@TheHardWay Can you elaborate on what metal tab you bent on the water pump install? Than you!
If it has a copper tube going up from the water pump look up in the mid shaft housing, look and see if the top fitting is still there or melted.
I was fighting with same thing on my mariner turned out top mount for copper water tube was melted and engine wasnt getting water supply it needed. After i replaced top mount, problem solved.
it looks to me lke there is an impeller issue. It is very difficult to see if you are getting the correct pressure using the ears because of the added pressure the hose creates. I am not a mechanic . If the thermoststs are opening and closing and you have verified the sensors are in good shape(no shorts in the lines) then the impeller is the issue. Are you sure the lower unit is re-installed correctly? Have you checked to make sure the fins on the impeller are turing the direction? Just some ideas from a guy that has been through it!
2 OldFarts Homestead Almost I just replaced the impeller before trying everything else. I’m pretty sure I got it all back together properly. I ended up taking it in to the mechanic. I’m interested to see what he comes up with.
2 OldFarts Homestead You we’re right! When I installed the new impeller, an o-ring didn’t seat properly. I was getting water, just not enough.
I know this is old video but there a pop-off valve on the side of your motor that might be bad need to check that
you r all right in my book brother
IR temp gun all around water jacket areas, it’s probably temp sender malfunctioning
Sir, First off get rid of the muffs.They will not tell you if the water pump is working. You are using the water pressure from your water source.I use a plastic trash can,fill it with water after you put the lower unit in.I would pull the lower unit,and inspect the rubber grommet that connects the tube thus insuring that the water is going into the powerhead. Do you have a thermal image sensor? Point it at something and pull the trigger, it tells you the temperature. Now I read the solved notice. here I am trying to help and some wise guy says solved. Glad you have the issue solved, Ken
Spring loaded
well we all learn somehow but brother id of dropped that t stat in some warm water and use a 1.00 cookin thermometer and check that baby at about 160 or 70
Take a water hose stick on the thermostat hole and turn it on I blowed out a 85hp evenrude that way
Hi, do you need to take off the lower leg to do this? Or leave leg/prop attached? thanks
Look at the common denominators first. Such as, the most likely culprit...
1. Has the dog been out in the boat on the lake when this overheating happens? Because every time you ignored him/her and went to start the motor instead of throwing the toy, I literally saw him/her walk over and intentionally stand on the water hose.
To test thermostat just boil the kettle and pour water into a coffee cup and drop it in...it should start to open right away
The poppet valve could be opening under load. The heads are clogged up.
Replace the sensor for good measure too- accurate reading is peace of mind!
Good measure, costs $60!
Use a tub not a hose and when it over heats disconnect one temp sensor at a time to isolate which side make sure inside of block is not clogged with calcium
You can test the thermo sensor - put an ohms meter on the sensor - then drop it in water that is about 185f -200f - then shut the water off - it will go from resitance to open when the water cools - drop some ice cubes in it as needed - the cost about $40
Also - next time buy a lasor thermometer - $35 it will tell you the engine temp - normal is about 125 to 160
Under head gasket there are things called deflectors that let water go around each cylinder. When those things go egg shaped they block the water from going around the cylinders. Replace them and it will run cool.
You need to take the cylinder head off as well on that bank that is getting hot you'll find that the water jackets around the cylinder wall will be blocked as well
Noticed he burned his hand on the left bank but not the right. Shouldn't be that way. I used to always feel each cylinder when driveway running.
I thought it was weird that the overheating horn did not sound, but the ramp rolled back as if it was over heated. It just coughed,,,, it did not puke.
I had the same problem too, it turn out that the new pump housing I installed to my motor didn't come with the rubber grommets for the pick up tube. I pulled the lower unit off again and compared the old pump housing to the new one and notice that there are two rubber grommet down inside the old pump housing for the pick up tube. Pullled them out and placed them into the new pump housing and reinstalled the lower unit. 😩👌
Man I’m really hoping this is the problem to mine i looked at the parts diagram online and I’m missing the rubber grommet that I guess keeps the copper pick up tube tight so hopefully that fixes it
@@travisgreen4451 It sucks having to drop the lower again and when you buy a so call complete parts kit for the water pump and there was no rubber grommets in it. I hope you still have the old water pump to remove the rubber grommets out of it, let me know if this resolved the problem with your motor. Good luck!
Look behind the water jacket gasket
Thats the head youre looking at,the water jacket is the piece you took off
bingo i was so frustrated watching knowing that the gasket was covering the water jacket with the gunk waiting to be seen.
@@bradconnor2856 probably still looking for it
Definitely the poppet valve. Dont remove all the wires you can take the screws out of the main plate and move it a side.
You have done plenty of work but here is two little things that I did not see in your investigations of the overheating. Take the thermostats out and ran a wire from the base of the thermostat house. Make sure that the passage is clear. The second item that I suggest, is drop the lower unit and at night time place a good strong flashlight in the brass/cooper pickup tube... the light should be inside the tube and no light should be coming out of tube specially at the end of the pipe..if you see break
In the pipe you are loosing pressure. The new news I believe are made stainless. Good luck
regular flushes with sulfamic acid will help clear out salts inside the water jackets
give me a pressure gauge mounted on TOP{ of the engine* the highesr point; usually at #1 and a restrictor instead of a thermostat and ENOUGH water and should be good to go. The T-stats can cook a motor if they don't open and that starves the jackets of water. A poppet is SUPPOSED to maintain the water 'charge' on the motor and only open AFTER a certain pressure. Make sure there is NO crud letting the water out. You can verify by taking off the cover and running the motor with the poppet valve in place and just hold the spring against it as close to regular position as possible. if ANY water is getting past the valve, the powerhead may not fully 'cfill with water ALL THE WAY to the top (usually no.1 cy) Just one of those cylinders running dry will overheat one of those motors (their water pumps suck) You should get a pressure switch into the top of the motor(near or above no. 1 and it should always read more than 5 psi but at speed , it should read 10 or more (25 would be better so no crap gets a chance to make a home in there. This may be too late to help you but it may help someone. Good luck.
Mine was the thermostat. Need to put in hot water. Mine only opened halfway
Chunks of my impeller got sucked up into the head and was clogging the water passages in a few spots
One thing with the muffs on the water hose pressure forces water up through the engine even with a bad impeller
Man I have the same problem.....Till this day....I still get an alarm at about 3500 RPM's!
Solved my issue. When I replaced the impeller initially, I bent a tab & that was causing a drop in the water pressure going up to the thermostats.
TheHardWay where was the tab you bent and what did it look like?
use deadblow
hammer to loosen casing
Pop it valve on side of motor. It regulates like thermostats😮
yep and that is the torque spec on the plate also
Change poppet valve when you change water pump every time
FIX!! YOU NEED MUFFS THAT SUPPLY WATER FROM BOTH SIDES! SINGLE SIDED MUFFS DON’T SUPPLY ENOUGH WATER FLOW.
Is there any way to measure the temp of the water coming out? Could the sensor be bad? All I know is this needs to be fixed so you can get back to that Sugar Shack build!
Yb Family Farm tell-tale water was cold. Water coming out of the propeller was hot. In my very scientific temp test, the port head was hot but I could hold my hand on it for 1-2 seconds...starboard head was so hot it almost burned me. I think I’m in over my head. To the repair shop we go...
My guess is you've assembled something wrong during your impellor replacement. Or overlooked something
I know that feeling
Did you find out what it was i’m going through same thing i changed water jacket gaskets water passages or good water flowing everywhere i don’t get it
The water jacket no problems
Yes sir im watching what do you youre engine. Im getting stock about my engine its a same problem i check thermostats and everythings water gose on its a same problem.pls help more about it.
It’s your poppet valve or thermostat
Change them both
Thermostat control the temp flow
The poppet valve controls the high rpm flow.
Heating when running 🤦🏻♀️ cooling when idling says poppet valve to me.
I got the same problem but when my light come on the motor is starts to run ruff like a bad skip l,m going to try new sensor.Get back with me
My yamaha 200hp hpdi outboard was overheating went over everything . In the end it was that the poppet valve had corrosion under the plastic washer that goes inside the block it was making it to tight so the valve was sticking had to hook it out cleaned it up with a round file got all the corosion off as best i could put grease on it put back together and now it doent over heat any more
A flusher is not good for trouble shooting cooling system assuming water pump has been replaced run in a barrel with a pyrometer should 143 to 160 temp sesors are notoriously fail alot
did you ever get your problem solved?
Head is clogged the problem is inside the heads if you don't want to spend money just buy Muriatic acid and dropped inside through the thermostar leave there for 10 minutes acid has to be diluded 1:20
Sila BATtaggia head was fine. See description or other comments. Hopefully your answer helps others.
Next time started up with the thermostat housing off and see if water gushes out of there
Do you think there might be an obstruction between the power head.and exhaust