Why is my engine cold to touch after a run?

S3 Nattie

S3 Nattie

Quattro ist für sissies
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I have a AMK engine. I recently repaced my thermostat as my temperature gauge was up and down, which it fixed. However a few days before fitting the stat I noticed that the engine is only warm when the gauge and climate control says its 90 degrees.

Before after a 20 min run I couldnt touch the strut brace, charge pipe or intake manifold but now I can keep my hand on it for however long I want.

Any suggestion would be great thanks.

Nathan
 
Because you now drive like a granny, simples :lmfao:
 
Maybe fans were on full throttle 24/7 when in use which the stat now resolved & also affected the temp readings, not unheard of.
 
Your hand was swapped whilst you sleep for one made of asbestos :)

Seriously though, it has....check it.
 
My fans are not on 24/7. They come on when the engines been idiling for a while in traffic or after I just start the car after a run.

I been told it could be the coolant sensor but not sure how that would make my engine stay coldish.
 
S3 Nattie said:
My fans are not on 24/7. They come on when the engines been idiling for a while in traffic or after I just start the car after a run.

I been told it could be the coolant sensor but not sure how that would make my engine stay coldish.
Click to expand...


It wouldnt, the water will still be the same temp before...the guage would be all over the place if it was the sensor?.

Odd one. Perhaps your car just has better coolant in it now and its doing its job a bit better than before?.
 
Ye I see what you mean. My car used to be boiling hot before after and a quick blast. I was constantly burning my hand on the strut brace or charge pipe if I had a quick fiddle, but know I can grip it and leave my hand on it for however long.

It is really confusing. My gauges are working fine and my climate control is giving off respectable reading. 51C which I think is oil temperature is contantly on 75 degrees, should that be on 90.
 
The coolant sensors are synonymous on this car to be replaced, think was swapped for green one, from a black version, front coolant pipe location, but not much else can dramatically drop temps that much except the fans afaik.

If coolant sensor/stat were fecked then fans would do all kinds of things tbh, had issues with the sensor, swapped out job done, also my fans were fecked at some point & replaced for new & stopped them running 24/7 IIRC, several reasons I guess, but cant see how yours is so low in temps now if fans are hardly running even with new coolant, I changed mine out recently, no difference but hey thats an 8P 2.0 tdi.
 
Could it be a air lock in the system. It doesnt overheat or use any coolant. When I changed the stat it did lose alot of coolant so I put in the correct amount of water and anti freeze in and the coolant level has been fine ever since.

I scanned the car the other day after changing the stat and it come up with one fault. Cant remember the code but it said something like interminet error in cooling mapped. Said thermostat or coolant sensor. I dont know if I have already fixed that problem by replacing the stat. I deleted it so will scan it again to see if it returns.


Edit: the code was 17704 Error in mapped cooling system (usualy temp sensor or thermostat)
 
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Ye there is warm air coming out. VAG COM is a few degrees colder than the CC though.

What sort of intake temps should you see on a hard run according to VAG COM.
 
on a remapped K04 with OEM SMIC's could be 60/70 degrees tbh....

<tuffty/>
 
I had this issue with my beastie..

I'm sure, as I said, it was the thermo/temp-switch/sender though. Will try have a dig and check it out for you.

*edit, sorry mate - I can't find the post.
 
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could just be the weather keeping it cool, i notice the heat soak in the summer & in winter performance is up !
 
not sure if this will help you at all, but when i changed my thermo + senda, then done a flush replaced with gen audi coolant it solved my temp gauage going up and down like a yoyo, fans going crazy and engine was noticably cooler than before after long runs, before it was same as yours boiling hot under there

now the colder weather has come along, mine struggles to get up to 90 degrees, will start to rise when stationary then dip slightly when first moving off again but soon creeps back up again, once it hits 90 it doesnt budge, ive just put this down to new senda, thermo and some 'proper job' coolant :)

as some one just said, im grateful for it running a slightly lower temp, for a few miles at least lol
 
Thanks for the suggestion. I done some logging earlier and after a quick blast my highest intake temp was 45 degrees.

I no the colder weather we are having will possible help keep the engine cooler. It great to have lower intake temps as long as the ECU has adapted and is fueling correctly.

Im sure its a problem as it was like this a week or two before I changed the stat with some mixed G12 I think it is. Thought it was down to that. Really confused what to do next.
 
Drain the system, refill slowly let it stand for an hour or 2 & then test again.
 
Check the top & bottom hoses of the rad. If after a run the top hose is hot & the bottom hose is cold, you either have an air lock or a stuck thermostat.
 
Siberia, lol, yeah good point check hoses there, one idea.
 
Ye that is a good suggest, will try it later. I read in another thread that there is a bleed screw on the bottom hose which comes from the rad, is that true.
 
S3 Nattie said:
Ye that is a good suggest, will try it later. I read in another thread that there is a bleed screw on the bottom hose which comes from the rad, is that true.
Click to expand...

as far as im concerned its a drain plug, not a bleed screw, but i maybe wrong, im sure someone will confirm this either way
 
Ok, where to is the bleed screw located to on these then.
 
you need to get under the car, as you look at it front on its the bottom right hand side rad hose, you should see a plastic plug thing on the bend of that hose, if i remember right just twist and pull to open
 
IIRC, the system is self bleeding as the expansion tank is the highest point on these cars...

<tuffty/>
 
tufftybloke said:
IIRC, the system is self bleeding as the expansion tank is the highest point on these cars...

<tuffty/>
Click to expand...


Correct, no bleed screw in the system as the tanks the highest point.

If there was a bleed screw it wouldnt be at the bottom of the rad, it'd be at the top where the airs at (or would be).

T
 
That does make sense. It would likely be a drainage hole if its at the bottom.

Bit of an update. Just when for a drive and stopped and felt the top coolant hose coming from the rad and it is hot. The bottom hose ( correct me if im wrong ) the one that goes to the thermostat was cold.

The temp gauge and CC are both reading correctly so i take it the stat is working, but the hose going to the stat was cold. It doesn't seem to be boosting as well either.

Any suggestions.
 
So you're saying you dont think the water is flowing through the rad properly, then I would empty the system & flush with hose through the system to see if it is indeed blocked or water is passing through, this would show a rad problem I would have thought, also if its a air pocket blockage then I would think this would remove this, then refill the system slowly & leave the coolant cap of standing for a few hours to allow the system to settle & the air to rise up & out as I did with my new turbo fitment recently, worked a treat.
 
Im not to sure if the water is passing through the rad. All I can say is that the thermostat hose was cold, the fans still come on at the right times.

Could I leave the coolant thats in there and leave the expansion cap off for a bit while the engine is idling to try and get rid of an air lock if it has one.

Not sure if this problem is related but when I went out for a drive, I turned on the front demistor and it sounded as if all the air was coming from under my glovebox. It has never done this before.
 
S3 Nattie said:
Im not to sure if the water is passing through the rad. All I can say is that the thermostat hose was cold, the fans still come on at the right times.

Could I leave the coolant thats in there and leave the expansion cap off for a bit while the engine is idling to try and get rid of an air lock if it has one.

Not sure if this problem is related but when I went out for a drive, I turned on the front demistor and it sounded as if all the air was coming from under my glovebox. It has never done this before.
Click to expand...


It sounds very much to me like there is air in the system. The noise you can hear is air going through the heater matrix under the dash.

I'd let things cool down a bit, pop to cap off the tank and let it idle for a bit. You should be able to see the coolant flowing back into the top of the expansion tank as it runs. Give the rad hoses a good old squeeze/pump to get things moving.

Then **** it down and leave it to stand and repeat if needed till its all out.

T
 
So basically take the expansion cap off. Let the engine idle and squeeze the hoses till the coolant starts to rise in the coolant tank, which should get any air locks out.

Thanks for everyone's suggestions, this is beginning to annoy me now lol.
 
Take the expansion cap off, & let it idle for a few minutes then hold the revs at about 2500 rpm for a minute or 2 still with the cap off. Then with it at idle start squeezing the top & bottom rad hoses, which helps move any trapped air in to the expansion tank.
Replace the cap & go for a run then let the car cool down & the check coolant level.
 
pauldazzle said:
Take the expansion cap off, & let it idle for a few minutes then hold the revs at about 2500 rpm for a minute or 2 still with the cap off. Then with it at idle start squeezing the top & bottom rad hoses, which helps move any trapped air in to the expansion tank.
Replace the cap & go for a run then let the car cool down & the check coolant level.
Click to expand...

If that doesn't solve it you may well have a blocked rad.
Be careful of using a flushing agent as I've had 2 rads split after flushing.
I'd recommend taking the rad out & back flushing it with a hose pipe instead.
If you're stuck try Mike & Justin at City Service Centre In Bedford St just off City Rd they are really knowledgeble, & trustworthy. Been using them for years. Tell them I recommended them & I'm sure they'll do everything they can to sort it out for you.
 
i dont expect the rad to be blocked imo, are you sure you got the thermostat back back in the correct way around?? (cant remeber if its possible to get it the wroung way) seems strange that you havent removed any air leaks if you have driven the car several times and let it cool right down again, if it is an air lock you could also try going for a drive get it warm then when you get home remove the cap slowly and carefully then leave the cap off till the morning (try the other suggestions 1st though)
are you sure the coolant is able to flow through the system have you had the water pump changed recently??
 
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