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Old 03-04-2006, 09:03 AM
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Cooling fans

My son has a 95 monte carlo and the temp gauge keeps pegging. I noticed that the fans aren't turning on when it gets hot. Do the fans run directly off the temp sensor or is the fan run through a computer that gets a signal from the temp sensor. Also he had a new Radiator and Thermostat installed last week and it still overheats which I'm assuming is because the fan is not coming on.
Sometimes the temp. gauge goes up but the heat is still cold. I thought this was the thermostat but like I said that was supposedly changed.
Any suggestions and info on the fan circuit would be helpful.

Thanks, Mark

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Old 03-04-2006, 01:31 PM
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cool possibilities

Gut instinct tells me that if your temp guage is pegging out but your radiator is still cool or cold, that your water pump is shot.
Im not any big strokes on electrical stuff, but if you can have someone test the temp sensor, or since they arent that expensive, invest in a new one just for grins and giggles, and put it in.
Aslo be advised that a new thermostat doesnt mean its working. Take the thermostat out, and if you have the old one, gut it and install the "washer" part of the old thermostat in your engine, see if things work better that way. If they do, then the new thermostat is your culprit, its not opening.
Be advised that it will take longer for your engine to warm up running the gutted thermostat, but at least you will get an indication if the water is circulating then as it should get up to about 120-140 degrees with in a matter of minutes.
If doing this thermostat trick doesnt show any difference, then check the water pump. An easy way to do that is while you still have the gutted thermostat in your engine, remove the return hose from the radiator, and start the engine. If it doesnt pump out water like niagra falls, then you know the pump is bad or else you have some kind of serious obstruction in your cooling system.
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Old 03-04-2006, 03:40 PM
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Doc here,

Is the car ACTUALLY overheating ? blowing out water, poor performance, bad smells?

or just pegging the gauge?

A shorted wire on the sender to the temp gauge will peg the gauge. (if the engine is still cool, the fans won't turn on yet..)

Which is yours?

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Old 03-05-2006, 06:18 PM
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I think it isn't realy overheating I think the gauge is getting a bad reading maybe from the trapped air ??? The temperature sensor, thermostat, and radiator were all replaced last week.
If you put it in nuetral when the gauge pegs and you step on the gas pedal sometimes the gauge drops to normal so I think it's a bad reading.
It's running rough.
But no smell.
There is definately air trapped in the system. You can see bubbles coming up from the bottom of the overflow tank. I think the gauge is just malfuntioning. But don't know why it is running so rough. A few folks had said it was the Headgasket that blew and that's why it's running rough but that's a $1,200 job so I don't want to guess. I've gotten about 6-8 different opinions from a $100 fix to $1,200.
I was always under the impression that if it was the head gasket there would be water in the oil or oil in the antifreeze and there isn't but someone on another thread said not always.
I'm open to suggestions. The car is a 95 Monte Carlo with a 3.1 engine if that helps.

Thanks, Mark
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