Is it normal for my '01 A4 Avant quattro 1.8T to be running at about 65c all the time? Very occasionally it might reach 68c when I'm idling or driving "with spirit", but for the most part it seems to stick to the 60c-65c range. That seems unnaturally cold to me. Especially since the thermostat isn't supposed to open until about 85c or so...

This was measured with a VAG-COM. The dash gauge confirms it, it never gets much above the first tick.

 

Get a new Thermostat. Or at least troubleshoot the coolant temp sensor and find out if thats working properly. i would start with the sensor. mainly because the thermostat is buried deep in Narnia on my 2.8...

 

I'm thinking ECT sensor is probably bad, since there's plenty of heat in the car even during bitter cold days (-20f and beyond).

But the ECT sensor also controls the auxiliary fan for the radiator. If it's reading that low, it might turn the fan on too late when I'm stuck in rush-hour traffic this summer.

How do I diagnose the ECT sensor? I just got the Bentley repair manual for this car, and I can't find any useful diagnostic procedures in it. Only ways to remove/install stuff. It's been a bitter disappointment so far.

 

Does the engine temp fluctuate at all once its been running for a while? If so, my money is on a failed open tstat. Usually when you do the tstat ($20 bucks at the most) you replace the coolant sensor (if not done already with an updated one).

 

I would think the thermostat has been changed otherwise it wouldn't run so constantly in that range. The lower ones sold I have seen are still above that temp.

 

I'm revising my theory. I just sat in the car at the hottest the engine will run and turned the heater on at full blast, and while the air being blown out was warm, it wasn't even close to hot. In our '99 A6, the air would be searing hot.

Both gauges (coolant and oil) look flatlined most of the time. The coolant gauge will occasionally rise up to the first notch or so under hard driving, but nothing more than that. Also, my consistent 30+mpg has dropped significantly in the last few days.

I'm not familiar with the car's history, I only just bought it recently. But now I'm thinking bad thermostat.

 

HOLY JEEBUS!

estimated 2.3 hours for a thermostat swap! And I just had a look at how much room there is to work on the front of the engine...

wtf?!?

 

What engine code is yours?

 

It's an AWM

 

oh okay, yeah my money's on the tstat