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Running hot when idle


kstables6

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kstable6:

 

Open the hood and make sure your cooling fans are running behind your radiator, you can't help but hear them. If you find that the fans are not operating, search this forum for help to replace the fans. The topic is well documented. Be careful that you don't overheat the engine, if you need to move it, flatbed it, it's not worth the risk to drive.

 

Good luck.

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kstable6:

 

My two cents.

 

From what you describe, this problem points to a faulty CHT sensor or thermostat . The fans seem like they're working. I'm not sure why the other fan is not running. Please test it again with the A/C on. A protective circuit in the PCM will prevent the compressor clutch from locking up to provide air conditioning of the engine is running too hot. This should not have any bearing on the other fan though.

Some things to check:

 

CEL on or off? The CHT sensor may be faulty "throwing a code". Do you have access to a diagnostic code reader? The more advanced ones can tell you the coolant temperature. "Feel" the radiator hoses, are they warm? As warm as the indicator seems to indicate?

 

Is the coolant level at low level mark when the engine is cold, and at the high level mark when it's warm? I'm assuming that aren't any coolant leaks. Pull the dipstick and make sure the oil is translucent or black and not frothy or milky looking.

 

Finally, This is a test to see whether the thermostat is opening or not. With a cool engine, start the engine. While the engine is warming up, place your bare hand around the upper radiator hose. As the engine comes to temperature, you will feel the hose suddenly get warmer. Indicating that the thermostat is ok. You should be able to "feel" the coolant flowing through the hose if you gently squeeze it. There are fans back there so watch your fingers.

 

If the hose stays relatively cool after the engine has warmed up, then the thermostat is stuck closed and need to be replaced. This condition will eventually cause the engine to overheat.

 

If the hose gradually increases in temperature at the same rate the engine is warming up, the thermostat is stuck open and needs to be replaced.

 

If you find it is the CHT sensor, replace your plugs while you're there.

 

Good luck!

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If it is a bad fan/controller you can get a replacement from amazon by Dorman for $150 and replace it yourself with autom8r's excellent instructions.

 

That was my symptom as well - both fans would run at engine startup but one would seize up after a minute or so. It would idle fine without the A/C on and the one fan but turn on the AC and it would overheat.

Edited by akirby
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