so today i replaced my thermostat to see if my car wouldn't get so hot when it was just running and i wasn't driving it. the needle got to almost 3/4. my electric fan turned on. it didn't turn on for more then 10 seconds then shut off. the car just continued to get hotter. it got almost to the red part and i shut it off. waited about ten min and put the key in the on position. needle was at 3/4. the fan turned on after a couple minutes but not for more then 10 sec again. shouldn't the fan stay on until the car cools down? is their something def that is the problem or should i just run a switch to it? thanks for the help.
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You may have a faulty switch, which switch do you have?
Additionally, if you didn't bleed your coolant perfectly you may have air in your radiator, which would mean the coolant isn't actually reaching the temp sensor.paint sucksComment
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how can i tell which switch i have? i opened the bleeder screw and their were a ton of bubbles. is it usually something you have to do more then once? this is my first time doing it on an e30. where is the temp sensor? in the coolant tank thing? i noticed that the coolant in there did rise. thanks for the helpComment
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If the engine runs hot at idle but not at speed, the suspects would be the engine driven fan's clutch, air in the cooling system, a bad thermostat, or a partially plugged radiator. It sounds like idle overheats were present before the thermostat was replaced, which suggests that the fan clutch or a partially clogged radiator may be the cause. But air in the cooling system could negate the affect of the new thermostat.
The first step is to test the fan clutch by dragging a rolled up newspaper against the blade tips with the engine idling. It should be easy to stop the fan when the engine and radiator is cold, but difficult to stop the fan once the engine and radiator are hot.
You also need to fully bleed the cooling system (procedure below). If the gage has reached the red one or more times, there is the possibility that air in the cooling system may be from a leaking head gasket. A single "trip into the red" has been known to take out the head gasket. A simple check for that is to fully bleed the system, drive the car for a bit and re-bleed. Release of a significant amount of air on a re-bleed is evidence of a leaking head gasket.
If the fan clutch is good, and there is no evidence of air in the cooling system and the problem persists, replace the radiator.
1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.
2) With the bleed screw open, add coolant until no more air comes out of
the bleed.
3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.
4) Once the engine is at temp bring it up to 2000-2500 for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.
5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.The car makes it possible, but the driver makes it happen.
Jim Levie, Huntsville, ALComment
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