bigbuzuki

I know that when mine dumped its coolant, I got the "low coolant" message and had no engine overheat.

I don't know about your hypothetical assumption about expansion tanks etc.

J'sWorld

Me either... But I do know the repair bills aren't hypothetical!

bigbuzuki

Mine had the coolant T pieces crack which dumped coolant.
I replaced them with these hoping to permanently fix the issue.

AGARubberDuck

I see many posts saying fluctuations like this is normal. I can tell you my 04 turbo is 100% rock solid at just under the 180 mark, well, after getting to that temp while warming up. I've sat in traffic for hours on 90+ degree days as well as the more typical idle while eating lunch. It doesn't move. ever.

J'sWorld

I agree 100% and truly believe the culprit is the fan controller.

J'sWorld

Nice tees! And certainly easier and more compact than piecing together a bunch of AN fittings.

djdeep

Hi all,

I know this is an old thread but could do with a little help before I start pulling this thing apart.
We had a cold spell a couple of weeks ago and took the car out but temp gauge didn't move at all (alarm bells) only a 3 mile round trip and then the next day took it out and temp went up quicker than it should and then went up to the 3 quarter mark and coolant level low warning.
Got it home and topped up but water leaking straight out and found the expansion tank cracked, replaced run car up to temp all seemed good so took it out and after about 20 minutes temp gauge up to 3 quarter mark then back to normal, after driving for another 20 minutes temp passed 3 quarter mark so pulled over and had it recovered.
It was spitting water out of the expansion tank oil temp was normal and now looking at it today filled up with water ran up to temp but it got up to temp too quick. Fans kicked in but blowing cold air from vents when up hi and on full.
So I'm guessing thermostat had it and maybe water pump but also temp sensor as I think it is reading hot too soon.

All thoughts greatly appreciated.

deilenberger

Kind of shotgunning the possible causes there..

You have air in your cooling system. The best way to get it out is a vacuum bleed system that pulls a vacuum on the entire system then fills the system with coolant while the vacuum sucks the coolant in. That's how a dealer does it. If you want to DIY - there are vacuum systems available at a not unreasonable cost (much less than all the parts you're blaming..) If you don't want to do a vacuum bleed - then (1) drive the Cayenne front end up on some ramps to raise the system and help air get out of it (2) turn the HVAC on defrost - which opens the heater core valve wide open - helping push air out of the heater (3) let it idle until air stops burping up in the coolant reservoir. (4) Drive the vehicle off the ramps and wait for the system to cool. (5) Top off the reservoir and close it It hopefully is now air-free. If not - I'd suggest going the vacuum route. FWIW - most people forget the heater core - and it needs some coaxing to get the air out. The clue air is in there - no heat as you described despite having hot coolant elsewhere.

And don't make the mistake of killing the messenger. I don't know how many people have blamed the temperature sensor/gauge - and then drove the vehicle and badly overheated it since they thought the gauge was lying to them - but it's a lot. That can get expensive.

Wisconsin Joe

If you think the temp gauge is off, get a temp gun. Harbor Freight has them for $20 or so (less with a coupon).

See what the actual temps are.

Gonna guess that the temp gauge is correct.

As was suggested above, you likely have air in the system.