VW TDI problem

[canuck699]

Hi Guys,

My Uncle owns a 2002 VW Jetta TDI Wagon.

Hes been having problems lately with the car getting warm. When driving the temperature warms up fine, but when idling the temperature gradually drops from 90 degrees to 60 degrees Celsius. He replaced the thermostat with a 195 degree and even covered about half the radiator off. He believes he bled all the air as well in case there was any in the coolant.

He was thinking a bad thermostat or it slid out of position when he installed the new one, however he could see it after and it looked correct. But the old thermostat did the same thing.

He has also had the water pump checked and it came back fine.

Any ideas?

[stefan]

Re: VW TDI problem

coolant sensor failing? hard to test without a vag-com, but if it has never been changed, it is a possibility.

[dJ]

Re: VW TDI problem

If its dumping more fuel or has more black smoke then it's probably the sensor failing. If the sensor isn't working right it will read cold and send more fuel into the engine.

[stefan]

Re: VW TDI problem

what kind of outdoor temps are we talking about? at -20 at an idle, my car cools down too.

[Red90]

Re: VW TDI problem

Sounds normal at this time of year. The heater uses more heat than the engine produces at idle. Don't worry about it.

[dJ]

Re: VW TDI problem

If he doesn't have the heat on....in the temps we have been having this week...it should stay at 90 no problem...

[Benjamin]

Re: VW TDI problem

How long is the idle?
Stock OEM thermostat is 87`c or 188`f, so from saying that you don't have an oem thermostat. So first I would find something either online or a dealer that was closer to the oem spec. I have put a lower temp one in a car and the thing would only heat up completely when pulling up a big hill.

If this happens in 5 minutes of idle at above 0`c temperatures with the heat going at 2 or less we have a problem. I know when we had the cold stretch I could leave my car idling for 5-10 mins on level 1 and the car would still be 75`c + when I returned. If I left the setting at 3-4 then yeah the temperature would drop fast, but this was -25`c at night.

Next question, timing belt done by who and did they replace the water pump?
The symptoms don't exactly match the classic plastic impeller problem, but I figured I would ask.

Ben