dustinw

Can someone here bestow some of their knowledge on me?

I'm having some trouble with my '97 Trans AM overheating. It's somewhat strange, and I'm not sure where to go next.

The car I believe must have some sort of problem with the sensor on the fan, since it doesn't seem to come on without the A/C turned on, but the previous owner installed a switch for the fan under the dash. When the car is at an idle without the A/C, or fan switch on, it starts to get hot (220-230). If I switch the fan on, it will cool down, and run at what I believe is a normal running temperature (180-200). If I turn the A/C on, it will usually cool to around 180.

I drive roughly 30 miles to work, and while I'm on the turnpike (doing rougly 75 mph), the car stays cool with no problems. Once I slow down, the car will start heating up, and even with the Max A/C and fan switched on, it won't cool back down.

It seems if I start it (from a cold start) and just drive around town, it's fine and won't overheat. But, it seems when I get it up faster, and then slow back down is when I have problems.

I've checked fluid, made sure there isn't any coolant noticable on the oil dipstick, and changed the radiator cap for good measure. I almost changed the thermostat, but since the coolant seems to be getting cycled (and it was when checking the coolant level) I didn't replace it.

Could it be the thermostat? Am I missing something? Is this an early sign of a head gasket fail?

Thanks for any help!

N20zuki

Could be thermostat is not installed and the coolant isnt restricted and spending enough time in the radiator to cool. Also check to see if the switch is wired correctly, he may have wired it backwards as well, air should pull thru the radiator not push thru it. May as well track down why he used a switch and its not coming on when it gets to temperature...

mannyman84

iTrader: (2)

U have reverse flow, these lt1's are critical with cooling. Make sure you don't have air in the system or it will overheat. Also make sure your water pump is working properly, check if it has loose bearings and also make sure your fan switch and your coolant tempeture switch is also working. Check relays sometimes they work and don't if they are bad.

dustinw

Thanks for the replies guys. I'm still poking around with the car. I failed to mention in my previous post that the car had the hose from the heater core spring a leak. It was rubbing against the motor, and wore a hole in it. The car got fairly hot when that happened, but I immediately pulled over and fixed the issue once I found it.

Do you guys know where the sensor that controls turning the fan on is? I was thumbing through a book, and they didn't have it listed.

Thanks again for all the help guys!

mannyman84

iTrader: (2)

Have u Tryed the one on the water pump? I think that's it

idformula

LT1's low speed fan kicks on at approximately 226° and the high speed fans kick on at 235°. Is this a good idea? GM thought it was, all LTx's are programed this way from the factory. If it gets over 230ish then Id say you have a problem. What I'd figure out is if the fans will kick on by themselves or if the p.o. wired it to they only kick on with the switch or the a/c on.
Personally I run around town with the defroster on cool, it cycles the a/c and therefore turns on the fans.
The sensor on the water pump is the one for the fans.

formula vincent

iTrader: (1)

you need a new cooling fan switch its on the passenger side cylinder head it turns the
cooling fans on when the heat rises over 226 degrees . you can buy them aftermarket from JET or slp
they come on at a lower temp to aid in cooling .