I have a M3 GTI and the temp gauge is reading what seems very low, over the summer it would get up to about 1/3 on the gauge, climbing to just over half if I got stuck in traffic for a while. Now if I am moving it hardly gets off the bottom of the gauge climbing to about 1/4 if i'm in traffic. Is the any way to check out the temp sender unit or gauge? and where on the engine is the sender? Thanks, Jester
I would say the most likely cause of this is a dicky thermostat that is stuck open! Have had exactly the same symptoms before on my car. The fact that we are now in to Winter means this kind of problem is easier spotted due to the lower ambient temperature!!! Good starting point before you start changing sensors IMO!
I think Chris is right. The sender is on top of the coolant pipe coming out of the front of the engine block. At 30 degrees C, the resistance should be 1500-2000 ohms. At 40 degrees C, the resistance should be 1000-1500 ohms. At 50 degrees C, the resistance should be 800-1000 ohms. At 60 degrees C, the resistance should be 500-700 ohms. At 70 degrees C, the resistance should be 375-500 ohms. At 80 degrees C, the resistance should be 275-375 ohms. At 90 degrees C, the resistance should be 225-275 ohms. Simon.
The coolant system might need flushing out too, but I agree about the thermostat. I replaced one on my Polo the other week 'cos that was overheating, 'stat stuck shut. You can test the old 'stat in a pan of water with a thermometer as you heat it up on the stove - your friends and relatives will think you are strange and make stupid comments like 'is it done yet' etc!
I've just had this problem, was adivsed it might be the thermostat but it wasn't. Plus the car was loosing coolant which turned out to be a tiny slice in the rad hose, only located via a pressure test. It turned out to be the temp sender. Got a new one fitted and then it did the opposite and over read saying the car had no water in it, and it was over heating! [:^(] Just had the sender replaced today got a VW sender which was 20 and all works fine now. Car temp is at halfway for normal running and rises slightly above the 1/2 in heavy traffic.
