I had another thread that was similar to this but I've fixed numerous problems since then so I'll just post another one. If I let car idle the temp gauge will never go past the halfway mark. If I'm driving it will go slightly past the halfway and almost to the next line but then goes down again. I have heat at all times but the lower radiator hose never gets hot and it seems like the engine only sucks in coolant after the engine has been running and I turn the engine off. Thermostat and waterpump are both very new as far as I know. I bled the heater core just for the hell of it and I burped the system but the lower radiator hose won't get warm or hot at all. After I burped the system the last time and let it sit for a 15 mins after shutting the engine off, I took off the resevior cap and the car sucked in half of the coolant in the resevior. The lower radiator hose was slightly warm at this time but still pretty cold. Also my oil temps stay around 200-225 mark when driving. I've noticed the gauge stays at the halfway and goes slightly past once the oil temps hit about 200. Also the coolant doesn't seem to move at all when the engine is running though, although it has to be or the car would be overheating alot more than it is correct? The only possible thing I can think of is a thermostat that is only opening halfway or something. Any other ideas??? Sorry for the long "story" Thanks Car is a 01 1.8t with AWM motor.

 

did you flush your radiator? they can corrode and plug up.

 

Yes, I just flushed the radiator last week.

 

Any more ideas.. lower coolant hose gets slightly warm now after driving the car for a while. Coolant needle still sits at a little above half when driving when oil temps get to about 200 deg range. After driving when coolant temps stay around 200-225 for a few minutes the needle will sometimes go right below half like it should be... So basically once the car is all warmed up the needle moves from below half to slightly above halfway mark. Oil temps never go past 225. I'm not sure im gonna put a 180 deg thermostat in when I get a chance.

 

i have the same problem as you.. did you fix it ??

 

I have heard that on some waterpumps, it is possible for the impeller to come loose rendering the waterpump, useless. Have you checked the thermostat for proper operation? When you say that the engine only "sucks in coolant", do you mean that you are using coolant?

 

The problem ending up being a leaking coolant flange. It wouldn't leak much and would not leak onto the ground. It was causing air to be in the system and not open the thermostat properly.