When I got the car two years ago it was running cold and the cabin heat was very weak (winter). I replaced the t-stat and it resolved the issue. Now the symptoms are similar in that the engine does not get up to temp, stays under 80, but the heater blows nice and hot. The engine isn't quite as cold as it was when the thermostat was stuck open so maybe that explains why I'm getting heat, it's almost up to temp, but not quite ... could it be that the 2 year old t-stat isn't closing fully? Before I get into it I just wanted to know if I should be checking anything else? How do I test the temp sender?

edit: I hope it's as easy as the thermostat but I have doubts. I replaced the coolant temp sensor (back of the engine) and this didn't start at the same time but not too far off ether, maybe I just wasn't paying attention. I do know that the car doesn't go into closed loop until the temp gauge hits 80c however because I was testing my duty cycle a couple of weeks ago and had to let the car idle in the driveway for a while (after driving it no less) before the temp came up and anything registered on the x11 port. I believe it's the coolant temp sensor that speaks to the ECU so my guess is it's registering the same temp as the gauge sensor. Am I making sense? This points to the thermostat being the culprit I guess but does it fail in this way?


Thanks

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1992 190e 2.6

Another question .. I don't really know what the normal behaviour of the fan clutch should be. The main fan is always spinning no matter the temperature. I can however, stop the fan without much trouble so I don't think it's "stuck" on. I just don't know if it ever slows down enough. Put another way, what is the normal behaviour of the fan clutch?

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1992 190e 2.6