YAMAHA 15 HP 2 STROKE, NO POWER, Problem found ( MUST WATCH )
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- เผยแพร่เมื่อ 2 ต.ค. 2024
- Yamaha 15 HP No Power, This old outboard threw more than one surprise at me 4 sure. But with enuff sniffing around & I found the issues & the cause of no top end on this abused little kicker, come along & lets see what it was. kodibass
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Thanks for taking the time to truly evaluate this motor. I learned quite a bit of troubleshooting techniques by watching this troublemaker aggravate you. Keep up the good work and videos. Kudos to you and thanks again. Hope to see it torn down and gone through and put back in service.
Thanks, Yep I hope 2 explore it more, But the owner will decide if I get 2. kodi
Dear kodibass, thank you for such an excellent video. Your sense of humor and knowledge make them a pleasure to learn from.
Thank U so much 4 the kind comments, & Thank you 4 watching... kodi
It’s nice to hear children playing outside in the background
Yep' glad U mentioned that, Me & wife talk about how wonderful the sound of kiddy laughing is also. kodi
In engines when the cylinder gets honed amwrong and has a taper to it from keeping the honing too near the top too long this same situation happened. As the engine gets warm and the cylinders expand the rings no longer make good contact and compression drops
Thank You Mate, Been A Head scratcher 4 sure. kb
Too long just get to the point. Most annoying video I have almost sat though.
Well' it took me 2 weeks to find the problem, But thanks 4 watching & your comments. kb
Thanks for your expertise.😊
Now, that we know what it is.... it does makes sense!
Plus, you're not crazy, and your compression gage is working well. Here is the explanation:
- The compression rings looked OK (& you commented about this).
- Looks like a small portion towards the top of both cylinders working bores was OK, as the scores/markings/pitting you found did not extend full length of the working bores .
- So, both cylinders were pumping pressure at the top of their stokes.
That's what the compression gage was reading.
Now that I can understand! Great expectation!!!!! Thanks 👍
Stick a fork in it!!!! Cause it's done 👎
Very logical indeed since the tester only gves the highest reading it gets at any time on the compression cycle. Thanks for sharing !
@@danielrobert7181 And, there is a moral of the story: what does a compression test result really means.
If the compression was only happening at the very last part of the stroke then the pressure would be much lower than a full compression strokes worth.
Watched 30 seconds and moved on.
This was a vary informative. Thk you
Most welcome mate. kb
Win some lose some the Outbord Gods got one over on you but you’re gonna get them back on your side 👍🏻🤘🏻
Well, this is a good reminder for all of us... Although compression tests should always be performed, we can get fooled by decent compression readings on two stroke engines...The extra oil can mask some powerhead issues. In this case, the rings appeared to be free so I'm not completely surprised by its decent compression readings. But, the pistons were definitely scuffed/scored, so I'm thinking this damage had more of an effect on the "primary compression", or crankcase pulses, causing the poor running. The loop scavenged engines will not tolerate any issues when it comes to primary compression. The old OMC cross scavenged engines can continue to run pretty well with scuffs and scores, but the loop scavenged engines won't tolerate it at all due to the complex scavenging and extra ports in the cylinders.
Now, as for the "pitting" on top of that piston, and in the head, I believe this is "detonation damage". In a four stroke/car engine, we can hear the engine pinging/knocking when we use lousy fuel, or perhaps leave it in a high gear and try to accelerate. Well, the two strokes experience the same detonation, we just don't hear the racket because there is no valve train. The pitting is from the crazy "explosions" inside the combustion chamber while detonating. Perhaps the owner uses this engine on a large heavy scow, and tries to run the engine at high RPM with a prop with too much pitch. Perhaps the owner is running some old or crappy fuel, full of ethanol, water, etc. Perhaps the timing was over advanced, the high speed jet was a bit dirty, or the engine was running a little hot. The top of that one piston might look that way cuz preignition was about to set in....
Such a shame to see an otherwise nice engine wasted like this, but you can't save em all I guess. That's some crazy reed valve set up...I think I get how it works though, those little raised ridges along the outside center of the reed case makes a seal between the two crankcases, am I right? Otherwise, that reed looks like just one reed valve for only one cylinder....
Sorry you ended up investing all that time and a non profit repair, but this is something we can all learn from, thanks!
What is a loop scavenged engine?? I’ve never heard that before. Thanks
@@mwatkins2464 Well, a loop scavenged engine is still a two stroke engine for sure. It just has a more complex way of delivering the fuel/oil mix to the combustion chamber. Cross scavenged two strokes are easily recognized because of that crazy raised "deflector" on the pistons, where as loop scavenged pistions are usually flat with a domed combustion chamber in the cylinder head. The benefits of the loop scavenged engines are that they tend to be a bit more economical than similar cross scavenged models...So, I guess you could say that the loop scavenging is a bit more efficient and tends to lose less unburned fuel/oil mix through the exhaust ports. The downside of the loop scavenged engines all all the bypass intake ports in the cylinders which mean less support from the cylinder sleeves, so the bores tend to wear quicker than similar cross scavenged models. The quicker sleeve/piston skirt wear also leads to a loss of "primary compression" in the crankcase, which usually is recognized by hard starting and poor idle. The conventional cross scavenged models, while less efficient, are way more tolerant of sleeve/piston skirt wear and continue to run fairly well, even with some scuffing and scoring....
@@fleetwin1 Thanks, what got me sucked in was the #'s plus how easy it started & how well it idled. uggggg. kodi
@@kodibassInsideoutboards yeah, I was surprised it idled as well as it did also....
Think this motor sat for a while with water in the cylinders and corrosion (from a partially blown head gasket between the cylinders), then the corrosion and rusty bits pitted out the cylinders after getting it running?
Unfortunately I too have ran into this situation. I think the only other thing that you could have done was a leak down test. But with those compression numbers I would have ruled compression out on my initial inspection also.
Unfortunately in this business sometimes things don’t go right.
Mate' them R some true words 4 sure. What puzzle's me the most is how easy it start's & idle's . kodi
I feel for you! I guess two oddballs in a few decades isn’t bad! Thanks for taking the time to document your work! Regards!
Thank U 4 watching. she still has lots of usable parts. kodi
Great video , just for shits and giggles , could you check the exhaust port (chamber) that goes down to prop exhaust ? Had a couple of Yamis plugged up to 90-95% blockage , should be a silver dollar size hole looking up the mid section but was only a thumb tack size hole .Plugged with carbon build up ! Enjoy the videos Kodi , keep on keeping on fella
Probably over rich mixture being added fuel tank , one guy was adding for a mixture of 40-1 on a 100-1 model !! Poor oil quality another colprit
I've noticed, or a least i haven't seen, that neither you or This Old Outboard do Hot compression tests. I have always been under the impression that compression should be checked cold and hot. It seems that with a hot compression check lower compression might have been detected. Great videos by the way!
I sometimes do but not always. If the numbers are iffy I will test , dry cold, dry wet, then Hot. thanks' kodi
I'd like to get my hands on this model 15 h.p Yamaha! They're supposed to be very good motors! The loop charged piston design makes them pretty darn quick!!!!
yep' U R spot on, lots of power very little weight...Good motors 4 sure. kb
Hi Kodi, I'm puzzled too? Good compression but poor performance. The inside looked bad and the pistons. Just a guess but one of the rings stuck on each piston and just enough oil or water to keep the compression up maybe giving it a false reading. Maybe the design of the head itself?
Sure could have been that' just plain strange 4 sure. kodi
@@kodibassInsideoutboards was the head torqued down before you started? Could be fine cold, but leaks when it is hot. Had an old Evinrude 35hp do that, the leak was internal in the section that separated the cylinders. New head gasket is all it was. But in this case, I think you had it correct, it was leaking water and it sat and pitted.
@@rrrttt1112 Yep' everything was good & tight. kodi
It would be worth homing and replacing pistons just to see if it fixes it...
But up to the owner
Owners call. thanks kodi
I have a 2000 15hp yamaha 2 stroke, i was intrigued by how you mentioned good comp both cylinders, mine has good comp both cylinders butonce it starts to warm up runs on 1 cylinder so i removed the cylinder head and found water in top cylinder, no scroring in either cylinder, am i correct to say the only way water could get into top cylinder would be through head gasket?
You're amazing Codi - I wish you were based in New Zealand as I would love you to fix my Mariner 15
Thank you very much for the kind words 4 sure. kodi
I need know more about 2strock
Great video thanks!
Thank u mate.
Oh Come on, just wind the rubberband a couple more turns. :)
I was gonna just paint 6hp on the hood & call it good 2 haha, kodi
Inspector Gadget figures out who killed the professor in the parlor with the rope!
That was a head scratcher for sure!
Yep' slow road 2 china but we got there. kodi
hi, I'm Italian and I'm about to buy a used Yamaha 15 hp from 1991. If I need spare parts, can I still find them or is it difficult to find them? do you advise me to buy it or better to go to a new one? Thanks!
I don’t understand why such good numbers but such bad condition ! The scoring leaves me to believe it ran without oil for a good time ! High carbon steel ( I know it’s aluminum ) when very hot will start popping which could cause the pitting , but aluminum will crack under high heat . I wonder if you pull the pistons you’ll seek cracks in the sides ?
Here is a thought: Maybe the scoring is just bad enough to prevent it from holding the pressure after the plug fires? Example: Maximum watts and RMS watts in a car amplifier. If the cylinder cant hold that pressure, it cant make much power? Cylinder leak test?
Kodi I had the exact issue afew year back with a couple of motors and what I have found is that the rubber plug that is in the carb that plugs the jet is missing I believe that is the problem with the engine. It will bog down at high speed. The jet feeds gas out of a small hole in the side and not directly out of the bowl
679-14966-00-00
I cleaned the carb very good the plug is in there, kodi
I'm with you appreciate your time get some rest
Thanks' sure will 4 sure. kodi
If there is any engine cylinder reboring/lining workshop nearby you?
like these videos
th-cam.com/video/9GEVbqDG6S0/w-d-xo.html
th-cam.com/video/tz3x_DZG0Vs/w-d-xo.html
After reboring, the cylider will be matched with a new piston, 0.25mm larger in diameter.
Thus, the refurbished engine runs like a new one.
Enjoyed the vid's, not available around here sadly. kodi
Adakah yamaha 25pk seken yg tidak dipakai kirim ke indonesia saja saya beli buat mancing..
Please don't be too harsh on yourself. Outboard trouble shooting is an art, not an exact science. Such stumbling over a diagnosis serves to proove there is no substitute to experience. I guess that taking compression tests on cold motors wiithout any load (spark plugs removed) reveals a good part of the story ... but maybe not all of it. Thanks for sharing, take care and most important, be merry !
thanks D, send me your address again & I will send U some clamps, I can get @ them now. kodi
Dear mr Kodi, maybe it can be another solution of this problem. Although those cilinders looks terrible. When pistons work it creates compression on one side and vacum on the other. This vacum sucs gasoline through carburator. This vacum could be lost through uper and lover seal on power head, and it could be tested with compresed air through carburator hole. If it leaks, it could be one of those seals.
That will be the owners call, His bill now is about @ value of motor. kodi
Alrighty then that’s that... great job on breaking it all down on the video!!!! 😅 👍🏻👍🏻
Thanks, Yep dat B dat. 4 sure. kodi
Kodibass, might you have made any videos that show views of how the neutral start and neutral speed limiter linkage is connected to a shift lever for a 30 horse Johnson ( mine is a 1998) with the remote shift cable connected to the externally mounted shift lever, what the mechanisms look like as they connect to the rope start and the throttle mechanism? I took my powerhead off, now can't remember how those safety mechanisms are mounted.
Yes' 4 sure I have but I have no idea what I titled them, sorry kodi
@@kodibassInsideoutboards I broke that plunger that operates the neutral speed limiter and neutral start only mechanisms on my 1998 30 horse Johnson. I cant find another one anywhere ive looked. It also puts the shift lever on a detent. If i were to use my motor without these mechanisms & the detent at the shift lever, would the detent balls in the gearcase be all i would need to keep the engine in gear & not jump out of gear?,
Hey kodi. What nut goes on evinrude 30 hp lower unit in front of the four bolts
Valdez. Loves ya sir
S.A.E 1/4-20 X 9/16 kodi
Thank u sir
Never assume anything ! Crazy shit there . Good find my friend 👍
U got that right' thanks kodi.
Need to stop all the b******* and just get the job done
Thanks for watching, & commenting 4 sure. kodi
So do you think it was a sunken motor??
Very well could have been, Ya never know 4 sure. It's ruff 2 say the least. kodi
Maybe it’s time for a new compression gage great 👍🏻 videos l enjoy watching and learning stay safe
I checked the gauge on 3 motors,, it's fine. kodi
You sure are thourgh way to go
thank u, kodi
I swear, I did not predict this the other day when I posted a question to one of your 2-year-old videos, ha!
weird 4 sure, kodi
incredible
Yepper'' first 4 me. kodi
Parts engine? It can be rebuilt
Yes' anything can B rebuilt but is it coast effective 2 do so? The crank piston set is a bit over 1,000 + shipping. Labor , gasket set.. etc. Owner said nope. So it's his call not mine. kodi
@@kodibassInsideoutboards where the hell are you buying your parts? Maura Mariner mag 2 150 complete rebuild kit with bearings Pistons gaskets and everything is right around $1,100. This is a 6-cylinder. There is no way a 2-cylinder is $1,000 unless you are buying a new crank for some reason already assembled which I see no point
A Yamaha 15 horse complete rebuild kit including Pistons Rings bearings and gaskets is around $350 this is including oversize Pistons
@@michaelflowers6048 I source parts widely , Yes I "" would "" buy crank / pistons / bearings as a assembly. I or no other shop on Kodiak Island has the needed Jig/press for the 2 piece crank alignment for proper bearing replacement. The cylinder case would also be replaced. All gaskets & parts would be OEM Yamaha, When I rebuild a engine it is my business reputation that leaves my shop. It is done to my standards or not done @ all. thanks kodibass
Actually the block would notI have to have anything done to it except a little muriatic acid to remove the aluminum from the sleeve in the blocked and rehomed. The only reason the Block sleeves would have to be pressed out a new one put in is if for some reason the cylinder was out of rround past the spec allowance, for some reason it was tapered, or the ID was out of spec. None of that was checked in the video. According to the video nothing was wrong with the crank or the rods. The Pistons are not pressed in so therefore no need for a press on that or any of the bearings except for your end bearings. Lowe's can be easily removed without a press and also they can be easily put on by leaving them in the freezer for about 3 hours. So really there is no need for a press. I have been mechanicing a long time and know the tricks to the trade. I don't know if you know these tricks but figured I would mention them. None of this hurts any internal parts on the engine as I have built performance engines before also. Learning these things could gain you a lot more business and would not hurt your reputation at all. In the end you would be making more money and also gaining more business and saving the customer some money. The one thing I do agree on is only buying OEM parts or upgraded parts