Temperature... issues.

[helpimonfire]

Got myself a 1.8T just recently (had it a week today actually) and I've noticed an odd thing.

The car warms up as it should, takes a few miles, sits at 90 degrees and that's where it stays. Until it decides to drop to the bump stop. The heater then goes lukewarm. There seems to be very little pressure in the expansion tank which makes me wonder if there's a blockage somewhere.

The pipe from the radiator to the engine gets hot, but the other pipes going to the expansion tank stay cold, with the water in the tank being lukewarm.

Any ideas? Worth taking the expansion tank pipework off and degreasing it? I have very little recent history with the car so I don't know if there's been any cooling issues lately. My usual mechanic is being all doom and gloom, telling me that someone must have taken the thermostat out and bodged the car, but I've now done 500 miles in it and there's no running issues (other than a squeal from somewhere, but that's another thread).

HALP PLZ.

 

[aragorn]

Duff thermostat?

Its a £10 part and pretty easy to change.

If the stat was missing it'd never get to 90 in the first place, i suspect its just weak, and when it does crack open it opens too much, overcooling the engine.

 

[Geeman]

I agree.

Mine was doing this, but ALL the time... changed the stat and everything's pukka again.

 

[phoenixv6quattro]

Agree with the gents above. There could also be an airlock in the system. Try bleeding it and see if it makes a difference. Cheapest option first! Lol!

 

[aragorn]

ye good point, that might explain the randomness of it

 

[helpimonfire]

The plot thickens!

Driving home tonight... absolutely faultless. Temp came up to 90 in the first few miles of town driving, then only dropped slightly when I was cruising at around 60*.

So yeah, I'll see about bleeding the system tomorrow and if it gets better, I'll still change the thermostat, for the sake of the £6.34 my local parts factor sells them for, it's worthwhile.


*err... honest, occifer.

 

[aragorn]

the "dropping" bit is classic faulty thermostat.

Once it gets to 90 it should stay there.

 

[helpimonfire]

So, the fact that the water in the expansion tank is cold, doesn't mean anything bad? I know a few things about cars but I'll be the first to admit I know f... very little about engines. Brakes, suspension etc... I'm fine with. Engine work... Noooo...

 

[aragorn]

nah its exactly that, an expansion tank.

It would eventually heat up with the engine at its normal operating temp, just depends how far your driving it.