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voy78
10-24-2006, 03:06 PM
I have a 2001 grand am gt. After the temperature dropped couple days ago to around 40F my engine keeps running cold. Couple seconds after starting the car the radiator fan turns on and never turns off. The temperature keeps steady below 100F instead of being 200F like usually. That happened to me once couple weeks ago (I was driving on a highway in rain, everything was normal and then the fan kicked in and temperature just started dropping), but the next day car was running normally.

I asked couple people around and most of them say that the reason for engine running cold is usually the thermostat stuck open. But... why is the fan constantly on? If I'm not mistaken the thermostat is purely mechanical part. The fan is controlled by the computer based on the coolant temperature sensor? Does the temperature gauge get the reading from the same sensor? If yes, then the sensor should be ok, no? Is it possible for the fan alone to cool down the engine so much if the thermostat is working properly? If not, why would those two failures occur at the same time? Or is the amount of coolant flow controlled by the same electronic system as the radiator fan?

Local mechanic said he changed the sensor and flushed the coolant. Then he said that the reason behind the problem is the lower intake manifold gasket leak... Something about the low pressure in the system kicking in the fan? Does that make any sense? Shouldn’t low pressure cause overheating, not the opposite? He said that repair will be around $600 and it will take two days...


Thanks in advance,
Wojtek

Sprucegagt
10-24-2006, 03:24 PM
Check your coolant level first. If the level is real low that would be part of the problem. If not, then you have a thermostat getting stuck open. The fans may be staying on due to the drop in coolant temp causing a trouble code. You may ask "Why isn't there a "check engine light?" Well, there are a few trouble codes don't trigger the "Check Engine Light." Instead you just get some mystery symptoms (i.e. cooling fan on constantly). In order to verify this, you need to have the car checked for trouble codes with a scanner.

CoopGT
10-24-2006, 06:33 PM
My guess would be you temp sensor crapped out on you or the thermostat.