VW T4: Overheating issue
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- เผยแพร่เมื่อ 9 ก.ค. 2016
- Thomas
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Tool box drawing was fine ! Good job !
That was a tricky one. You did a good job explaining the issue and even though I don't own a VW, but it's not out of the question to own one some day. I'm leaning towards a TDI wagon of some kind (Golf, Jetta) then I'll be back to visit your videos again. :)
This can apply to any vehicle... so go get that Ferrari you always wanted! :)
Nice video Thomas. I've run into this problem of getting bad "new" parts. It can drive you crazy.
Luckily it does not happen that often! =)
Thanks so much, very kind of you!!!
Good to you yes
Thank you for watching!
"They don't make'em like they used to!" applies here!
Totaly agree with you.
Very good teach to fans people
My bleed screw is at the highest point on one of the hoses, quite near the center and not far below the windscreen.
Works a treat.
Yes... all T4's have it, as can be seen at 0:30 . That alone will not get all air out, if the bleed fitting at the head or radiator is plugged... air can get trapped.
Nice explanation. Unlucky with 2 dodgy switches, can't say I've had too many issues with new VW (aftermarket or genuine) parts.
Yup, so true!
Thanks Thomas for the video. On one of your videos where I explained my challenge with my cooling system. I did a test on the two thermal switches I have. At boiling water temperature on the switch that came with my car, I could get continuity between pins 1 and 2( which is the low speed fan) but no continuity between pins 2 and 3 (high speed fans). On the other switch I got from a junk yard from same car as mine, at boiling water temperature, I get continuity on all the three pins on the switch. Both switches are stamped 102/95•C and same part number. However, when both of them re in the car, the fans will not come on any speed. Bridging the pins, the fans come on both high/low speeds, indicating fans and relays are good. Water pump is fine. I blew through the reservoir bottles, just to check if any blockage, and coolant comes out from the opening the switch was removed from . Currently, I had to manually introduce a switch to control the fans. Is there something else I am missing? I have changed the fan control module, thermostat and this mystery remains. My car is a vw Bora, with 01M transmission, same as golf/jetta MK4s.Thanks again for your patience in solving problems.
If the switch / radiator does not get hot, then the switch will not turn the fans on. If the thermostat is new / good, then the radiator should get warm. If the radiator does not get warm, you need to check why. If the radiator DOES get warm, then the fans should come on when the switch gets hot enough (since you confirmed that they do work). How hot is the engine / radiator getting? Needle in the dash / how high does it go? Post a video on your channel so that I can see.
Needle stays at 90•C. Using VCDS, temperature gets to 105•C and increases if engine is left running. Radiator hose gets very hot. Touching the coolant in the reservoir or the drain lines are so hot.
@@pauliroha5506 Then there should be no reason why the switch is not getting hot. Since the fans work when you bridge the wires, the fans should work with the switch (since you verified switch operation outside of the radiator). There's nothing else I can suggest, sorry.
Awesome vid. Take away message was great and the diagram of the cooling system was perfect. As my math teacher always said, K.I.S.S. (keep it simple, stupid).
Thank you and thank you for watching!
Hey Thomas..trying to catch up on your videos before the week ends out. I blame Steve Robb because with all these new subscriptions, it's getting harder to keep up LOL..That was a nice job of explaining the cooling system and what you found. Who would ever thought that two switches would be bad? And you're right that quality is not the major player in today's world. It's all about being cheap and quantity. It must be the new business model for today. Good video Thomas and have a good one!
Thank you... I'm having the same difficulty keeping up with all the channels. Steve needs to fabricate more and not recommend channels! LOL
HaHa! I was thinking of the same thing too!
I had new parts last week that failed. Thomas were they after market?
Also, had to remove the fan flaps actuator (in the middle of fans) as it didnt open and open the fan covers by turning them with force.
Thanks for another Eurovan video.
How do you test the after-run coolant pump?
Also, Eurovan has radiator shutters. Can these be tested?
You can apply power & ground to the pump directly to see if it turns... they are meant to run when the engine is off and the engine is warm from heat soaking / coolant not circulating (110c I think). Checking under those conditions as well as the appropriate fuses, wiring, relays / module should determine if there is an issue that needs to be investigated.
The mechanical thermostat between the fans is heat sensitive... if it does not move the fins, the thermostat is bad. With the thermostat removed, you can check if the fans are stuck or if they are free to move. If you leave the thermostat out, make sure to position the fans so that you get adequate air flow through them... for your current climate.
Good one Thomas...
Like your explanation.
So easy, a ten year old can get it..hahaha.....
I put temporary manual switch for the fans, that I can switch while driving.
I wonder if the switches were actually faulty, or if they were mislabeled. I know there are two, possibly three different temperature ranges for that style of switch, and each range gets matched with a specific temperature thermostat to control coolant temperature. I've gotten the wrong thermostat in a box before on more than one occasion, so it's not too far-fetched that a batch could be mislabeled. :)
+rhkips Possibly... but these sensors are also matched to the connector (locating tab). If the connector fits, then it should be the correct sensor. I've seen different temp values on same sensors over the years (for different climates etc)... but at 3/4, I wasn't gonna wait any longer). :)
Hi Thomas. What a useful video for understanding the cooling. I actually have a issue with my T4 2.5L petrol AET manual without AC. It takes a very very long time to heat up to 90 degrees. Sometimes it can take up to 30 minutes, if not longer. I replaced the thermostat and the two coolant sensors on the front of the engine. There’s no leaks. How would
You go about diagnosing such a issue?
Any help would be great. Running out of ideas.
Thanks again
I would use a scan tool to monitor coolant temperature... to see if scan data matches the temperature gauge. New parts can be bad... could be the thermostat. If the lower radiator hose is warm at 70c or 80c, then the thermostat is opening early.
Thanks a lot Thomas. Love the channel. Has helped me a lot to fix up my 300.000 mile petrol Eurovan.
You may have sorted this by now but to anyone else reading this. Check out the instrument cluster power supply solder dry joints, they are a common problem effecting temp and fuel gauge response. A few videos on youtube cover it.
Hi. Great video. I have no coolant flow so my fan kicks on after relatively short journeys. I have the the eurovan aja engine type. Does the switch you mentioned actually activate the pump for coolant flow or do you think i need a new water pump? The water pump and cam belt were only replaced about 4k miles ago. Any help appreciated. New subscriber too.
Thanks.
Pete
Do you have any overheating signs Temperature needle going past 3/4? No heat inside the van? If not, then coolant flow is OK. The fans are triggered by the radiator fan switch... if you have no flow, the switch never gets warm / hot.
Thomas EXOVCDS hey thanks for the reply man. Once up to temperature the needle is steady at halfway. I just notice the fan kicks on when i stop at light etc once it up to temp. Seems weird it needs to kick on so much plus garage said i had no flow.
The return hose to the bottle might be plugged. If you have no overheating issues and heat inside the van... all is fine. Fans should kick in at a steady interval once the engine is warm.
Thomas EXOVCDS Thanks for your advice i really appreciate it 👍
Logic one but logic two , you really have to be confident in yourself to pull that one off. I could see a lot of rabbit holes appearing for me. LOL
+STEVE ROB Third time lucky... I always say!
LOL, me too. I'd get lost and confused about everything!
Holy crap no way! They really don't make them like they used to! I literally just replaced my mk3's waterpump, thermostat, fan switch, and temp sensors. I had the system bleed all of the way but the fans would never turn on. I tested everything and although the high speed doesn't work because the fan control module is faulty, the low speed does work when I bridge the connections on the plug. Come to find out the brand new fan switch is completely dead... The brand new thermostat housing was also leaking at the adapter because it's not tight enough, so I had to put the original one from 1995 on and there is no leaks... That's pretty sad.
+SlipknotMaggot0526 It's harder finding better parts for older vehicles. The coolant flanges might even have vw logo & part number rubbed off (genuine mold)... but the plastic used during the production is a lower quality.
HI Thomas, Thanks for great explanation and taking the time to video this,, I brought a T4 today, 1995 model and drove it home 160 miles, the heat gauge was worrying me as it went up to the 3 quarter mark and I know from my golf and other vw was the temp gauge should be in the middle, I could not hear the fans kicking in, I was in traffic and its a hot summer here in uk so I am worried, I opened up the bonnet when I got home and the resivour is rust coloured but it looks like they have put new coolant in, the fuel gauge was erratic also , it some times doesn't work the seller told me, so always fill it to top with fuel, he told me to tap the dash,,
well any advice as to where I can start ,, I am no mechanic but can try simple stuff, would really hope I can get idea if I can fix myself but would need mechanic to do thermostat ,,
when I slowed down to around 50 mph after the motorway at 65 mph the temperature gauge did drop a bit but I was really worring the temp was running hot,
thanks in advance !
Verify with a heat gun / infrared temperature gun that the engine is running hot (or by touching the upper & lower hoses). Bridge the low & high speeds manually at the radiator fan switch. Replace the thermostat & flush the system for good measure. Follow the following video to activate the fans... let me know what happens. Leave the van at idle with low speed ON (if they are working) and see if the temperature stays low. If low speed does not work... replace the resistor packs (but check fuses first). =)
th-cam.com/video/6tU0e6SK1ig/w-d-xo.html
Thank you very much for informed reply! you are wizard with engines, im impressed with your work, thanks for posting it and thanks again for the reply along with link
How to get quality parts these days? Are there still some brands we can turst?
Buy from parts stores that specialize in selling VW / Audi parts.
Having overheating issue vw t25 change thermostat / Fan switch temp gauge sender / fan doesn’t kick in at all .. any advice please
How quickly does it overheat? Based on what? LED light in dash flashing? Temperature needle going past 3/4? Coolant leaking out of the overflow tank? Which engine? Does the fan switch have power? Does it overheat while cruising at a steady speed? The more info I have, the better I can guess what the problem might be.
Hello, I have a 1.9 tdi t4 transporter 2001. I topped up the coolant and left the cap off (I forgot) drove to and from work (7miles), on the way back the engine temperature light came on and the temp gauge was showing high temp. I shut off the engine and waited. I drove home. The coolant expansion tank still was full but seemed to be under pressure as I could hear a slight hissing sound from the cap. I took it for a test drive later and the temp gauge would go right down then back up to hot erratically and the light would come on for temperature with a beeping sound. This was after driving a few miles. What could be the issue? Is it the thermostat or air in the system or something worse? Thanks for your help
Could be air in the system. With the engine at idle, check for coolant return flow back into the bottle... via the small return flow. If you have no flow, shut the engine off, remove the hose and blow into the hose. If you can blow into the hose (look for level change in the bottle while blowing), then check for heat inside the car when the engine is running. If you have no heat by the time the temperature needle is in the middle, then the water pump is bad.
Of you can not blow into / through the hose, then you need to check for a blockage in the hose or at a T junction. Clear the blockage and the engine will be able to bleed the air out in to the bottle. Coolant level will drop... top up as needed.
thomas,what are the best wintertires for t4? cor
Sorry... not sure why / how I missed your post! We don't deal with tires at our shop. You probably already dealt with this by now... a tire shop would be the best place to talk to.
hi. I've changed my thermostat due to overheating and the buzzer going off. Top rad hose is hot on my t4 2.5 88bhp but the bottom is cold and the rad isn't hot and thermostat housing is cold. Other hoses and the hot air is very hot...too hot I think. Can work out what to try next...could it be an airlock...new thermostat works as I checked and no air I dont think. Revving causes the expansion tank to have good flow too..ta
Not sure.
There are 2 return hoses that connect to the coolant bottle return fitting.
One return line is from the back of the cylinder head and the other is from the radiator.
Disconnect those hoses at the T fitting and check to see if either of them is plugged. If yes, unplug it and then check for overheating again.
You can have flow back into the reservoir if one of those hoses is plugged... but then still have air in the system.
If you have heat inside the car, then the water pump should be ok.
If both hoses are clear and you are sure that the thermostat is OK, then maybe the radiator is plugged.
@@EXOVCDS thank you.ill have a look. I think I know what you mean.
having this issue in my A6 2.7t timing,thermo, w.p, n tempsensor, done less then 1k ago. I've bleed n bleed the system n still goes over the center.
+Trinidad Cerda Have you compared ECM coolant temperature with instrument cluster temperature (instrument cluster scan tool live data)?
Or performed an output test of the instrument cluster gauges?
Maybe the needle is offset slightly?
+Thomas EXOVCDS have not tested non of the above. for now just gonna go to the old junk yard and get some old genuine fan sensors see if its that. I have no coolant in the oil so I'm pretty sure its not the H.G's . last night the needle was a little over but would just stay there
no 1
LOL!
My T4 seems to not get hot enough, moves just about bottom segment of temperature gauge any ideas, new coolant, fan switch works and new expansion bottle fitted
Is the fuel gauge behaving correctly? Can you check temperature with a scan tool (ECM data)? Or checked temperatures under the hood (radiator hoses) with an infrared heat gun? Could be a bad temperature sensor or a fault with the instrument cluster. Bridging the temperature sensor "needle" circuit at the sensor harness plug... to see if the needle goes full hot, can help further diagnose a low needle.
+Thomas EXOVCDS hi it's a 95 1x diesel so no ecm as such I'll try get temp with infrared sensor later fuel gauge works perfectly
+Joseph Dempsey If you also have low heat output inside the van... the thermostat is probably stuck open.
+Thomas EXOVCDS heat in van is perfect warms up nicely sometimes it feels to warm, I'm going to try another temperature gauge
Joseph Dempsey I would start with the sensor.
I only second guess myself once then it has to be something else. Where the switches made in China?
Probably.
I am having this problem but can't take it to a shop as I cant drive it because the coolant shoots out the reservoir like a volcano after warming up . Ive decided I should replace those return hoses coming out of the reservoir Im come to the conclusion they are hard as a erock when squeezed and probably rotted inside . How do I get to the end part that disappears in the manifold ? Thank you.
Coolant will shoot out of the reservoir when the cap is removed, because pressure builds up. If the reservoir is leaking even when the cap is in place, either the cap is bad or there is too much pressure in the system (bad head gasket or stuck closed thermostat). Follow the hose to the passenger side of the intake manifold. The hose is attached to a pipe sticking out of the head next to the intake manifold.
@@EXOVCDS The reservoir and cap are new. When I have run it cold with the cap off it shoots out in about 15 or 20 mins after warming up, not taking the cap off after hot. I could not see even with a flashlight where the hose ended in there. Is there a trick to removing it, It 100 % needs to be replaced. I was going to try to find out how to do the vacuum thing but realize these hoses are just bad . Its hard as a rock and Im thinking it is swollen shut inside.
Remove the reservoir cap, remove the hoses at the reservoir T fitting. Blow into each hose (the one that goes to the radiator and the one that goes to the side of the cylinder head).
If you can not blow through the hose ( you should be able to see the fluid in the reservoir react to the air being blown into each hose) then the hose is plugged.
If you can blow through the hoses, then you don't have to deal with them right now and the problem is something else.
Keep in mind that on a correctly functioning cooling system (no air in the system, no head gasket issue, no thermostat issue)... those hoses can get plugged up and NOT cause any issues.
Meaning that, even if your hoses are plugged, that there is an underlying issue besides plugged hoses that needs to be addressed.
@@EXOVCDS With Cap off and Reservoir side hoses off. I first blew in to the one leading to the engine and after pushing/blowing hard for about 10 seconds I saw some activity in the Reservoir water .Next I blew in to the radiator hard several times , no activity in the Reservoir .
The nipple at the radiator is probably plugged. Remove the hose at the nipple (move the radiator into service position to make it easier to remove the hose) and poke the nipple with a suitable small nail or drill. Once both hoses have flow/ are free to flow, air will be able to get out of the engine into the reservoir. If over flowing/ too much pressure continues, you need to verify thermostat operation.
On my T4, the needle reaches 90 then starts dropping. After a while reaches 90 again and starts dropping again.
If it drops while standing still... temperature sensor. If it only drops once the vehicle is moving... thermostat.
@@EXOVCDS Thanks! I forgot to mention that the thermostat is new.
@@jpborralho it's the 4 wire sensor... not the blue 2 wire one for the ecm.
@@EXOVCDS On the third trip (less than 10Km on the highway), it took a while to reach 90 but then sat with no drop.
What brand were these defective parts? We are seeing allot of problems; from aftermarket parts and because of globalization, it is becoming harder, harder to judge the quality of parts being sold these days. These brands; I have heard of causing issues (offshore asian production; many times, inferior chinese): "Meyle Germany" (note: kind of deceptive marketing; as this does NOT denote German made parts), Hamburg Technic, URO, MTC, Airtex (poor quality fuel pumps), etc.
See a trend here? European sounding names; while, they are not made in Europe, USA, but asia. While, I cannot say that I have seen any myself; I am reading the auto repair trade magazines, that the North American market is being flooded with counterfeit parts, as well. Things are defintiely confusing on the global manufacturing market; even parts I am buying from VW are being made in China, along with classic long term German VW oem companies like Bosch, etc.
+Billy P. I don't recall seeing any markings on the thermo switches. It's gonna increase comebacks or delay jobs (like this one) if caught the same day. Either way, customers won't be happy and won't care that we aren't happy not being able to get decent parts.
Globalized parts manufacturing; is making it harder to find good parts and ascertain, if the quality is good! :(
soy el primero
LOL!
Wow worn out
Too much water in the cooling system... caused rusty water.
+Thomas EXOVCDS I've always run the correct mix with VW coolant. It's still clean.
If you have an email address to send to , I can explain the situation .
We're doing pretty good here, no?
@@EXOVCDS Yes , though it's a long story of what's happened up to now. Tomorrow I'll do what you told me and report back.
Howdy. So I replaced that radiator and in the process the fuel line tube ( nylon I was told ) cracked, the line that goes in to that round black thing with a vacuum line on it on the engine . I was going to repair the fuel tube at the crack but I decided to be safe and run a long fuel hose down to the fuel filter and and connect to where it is on the block. Now it will not start ! I sprayed started fluid in to the manifold and it starts for a bit .It seemed so simple, what could be the problem ? Thank you.
Remove the fuel hose from the "black thing with the vacuum line" ... point it into a container and have someone try to start the engine. Fuel should come out of the line. Yes / no? Fuse 18 should be fuel pump fuse. Is it good? Yes / no?
@@EXOVCDS Yes I did that yesterday though it was just me . Fuel pump fuse is good, pulled the hose stuck it in to empty water jug turned key for a few seconds and went to see jug and it had about quarter of a pint of fuel in it.