[Mk2] [Turbo] Intercooler cracked ??

[lee.w]

how do you know when your intercooler has cracked ? , here are my symptoms.

thermometer needle seems to be higher then usual especially when idle and i have also recently heard loud hissing noises sometimes behind the drivers rear ,but the weird thing is, the thermometre needle reached peak heat today in traffic which it never really does, but the engine didnt feel that hot at all on the engine lid when i checked, plus i put my hand on the intercooler when the engine was running and it didnt feel hot at all. possible slight crack in intercooler ? or faulty thermometre.

[cvega666]

I dont see how intercooler cracking would result in water temperature sensor reading wrong... is your car still boosting properly?

[g.lewarne]

sounds like bog standard thermostat fail to me?

[lee.w]

it does boost ok i guess , i can certainly hear the turbo spool up anyway but the strange blowing noises i have been hearing today are coming from the intercooler area I think does that mean possible water or boost pipes even thou i cant spot anything by eye at the mo. so if the car boosts ok does that mean the intercooler is fine . yea the thermo gauge does seem to be skyrocketing when idle but then drops considarbly when driving again, even thou the engine seems luke warm

[cvega666]

well, if you had a cracked intercooler, that would probably cause the car not to boost right - i.e. not go forward when the loud pedal is pressed.
I'd sort the thermostat first, it's not a very hard job and cheap part.

[swaggansway]

ic failure is very unlikley. more probable that a jubalee clip needs tightening up to cure your hiss! be very carefull when you change thermo that you don't round off the 10mm nuts securing it, the bottom hard to get to one is worse! someone else on here has got that problem now his thermo cover is bloody stuck. he must have baught every tool in the shop to remove it to no avail. I think he is now taking it to a pro to sort.
when u put ur new thermo in be sure to line the wiggle pin thingy with the notch on the cover. it will be obvious when you do the job!


just a quick thought tho, if his thermo is stuck shut it will always overheat. if it is stuck open it will take a long time to heat up from start and then will run too cool

[g.lewarne]

could it be sticky thermo? like it takes lomger than normal to pop open when it needs too? rather than just broken?

[swaggansway]

ah yes I have had that before. I might have s spair one If op is interested!

[willfinch36]

Easy option: thermostat.
Worse Case: Head Gasket.

[toxo]

Easy option: thermostat.
Worse Case: Head Gasket.

Unrelated to your temperature problem: intercooler

[swaggansway]

+1 buddy, fingers crossed for you. I suggest compression test as first port of call

[asdrewq]

+1 for thermostat.

Could also be the rad fan at the front not coming on (hence overheating when stationary), or could be a failed waterpump impeller not pushing coolant around the engine fast enough when engine is idling for long periods in traffic.