Mechanics

99 OCCASIONALLY OVERHEATING AT IDLE

1999 Saturn SL2

Engine Cooling problem
1999 Saturn SL2 4 cyl Two Wheel Drive Automatic 130000 miles

Works great majority of the time, car reaches temp (about a 1/4 on coolant temp gauge where its been for 10 years) and stays there.

Increasingly often, lately once or twice a week, when at at a stop and idle, car starts overheating and gauge rises slowly to half or higher and starts to run rough. Once moving again (getting air flow?) Gauge goes back to normal.

Any help on narrowing it down appreciated, is it cooling fan? Sensor? Thermostat?
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Billy9999999
March 29, 2010.



Hi: If this only happens when you are sitting and not moving, chances are the cooling fans are not turning on. Once you start moving and get the air flow moving again, the temp goes to normal tells me the cooling system is working properly.

The next time this happens, pay attention to see if the cooling fans turn on. You could just let it idle in your driveway to check it.

Let me know what you find.

Joe

Will do, but it is intermittent so may be awhile before I get the opportunity to check it when its overheating.

Question: on previous cars I've had, the fan was always on, these were old GM belt driven. On this Saturn whats the story: is it a variable speed fan, where it may look like it's running all the time, but is actually running at different speeds based on conditions?

Just wondering exactly what I should be looking for. Thx
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Tiny
Billy9999999
Mar 29, 2010.
Actually, they are electric. THey are mounted to the radiator and are part of the shroud. They turn on when a certain predetermined temp is reached. The temp sensor sends a signal to the computer (PCM) and then it sends a signal to the fan relay which in the end sends power to the fans. With the engine off and cold, open the hood and look on the back side of the radiator (close to the engine) and you will see them.

Let me know if you have other questions. Also, let it idle in the driveway to see if it happens.

Joe


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