Overheating

[rbsteve]

When driving on highways my temp gauge read 1/3 all the time, nice and constant. However, during city driving, or when my car is idling, the temp gauge climbs to 2/3 and stays there. It only goes down again when i pick up speed.

I think it may be the radiator cooling fan switch...

Does anyone have any experience replacing one of these ? Is it expensive, or do i have to replace the whole fan assembly ?

98 grand prix SE, 3800 engine

Thx

Steve

[Phoenix69]

My 97gt with 54k miles has had a similar problem. It gets up to 210 or maybe a little higher. We have had weather of 85+ all summer. I don't know if this has anything to do with it. After i drive a while and park my car for 5 minutes, when i start my engine, the temp is very high for a few minutes or until i start driving. Then it levels out. Kind of confused what exactly is happening.

[theblurr87]

Originally Posted by rbsteve

When driving on highways my temp gauge read 1/3 all the time, nice and constant. However, during city driving, or when my car is idling, the temp gauge climbs to 2/3 and stays there. It only goes down again when i pick up speed.

I think it may be the radiator cooling fan switch...

Does anyone have any experience replacing one of these ? Is it expensive, or do i have to replace the whole fan assembly ?

98 grand prix SE, 3800 engine

Thx

Steve

that's extemely normal for our cars. mine used to be very similar till i put in a 180 stat. Stock they have a 210* fan turn on. As long as it's not going above that you're okay. If you haven't had a coolant flush done yet i might recommend you go ahead n do it.

[BNaylor]

The first thing is you should check to see if the 2 cooling fans are working. There is no cooling fan switch per se. The fans are controlled by the PCM computer through low and high speed relay switches located in the engine compartment fuse box. The PCM references to the coolant temperature sensor (ECT) to turn the fans on. Normally they do not turn on until the coolant temperature reaches 223 degrees.

To check the fans, take the car out for a run and turn off for a few minutes. With the AC in high and max cooling start engine. Both of the fans should be spinning either in low or high speed.

I agree with Blurr87 on the cooling system flush if it already has not been done and installing a 180 degree thermostat. Good luck!





Thrasher CAI, DHP v1.0 PCM,
3.25 SC pulley, CAIT GMAF, Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 TB,
TB spacer, MSD 8.5mm wires, Autolite 104s,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials

[1998GTP]

-- My car just started doing the same thing about a week ago. I have replaced the themostat as well as the cap. Have any of you noticed any difference in performance?


Thanks

Originally Posted by bnaylor3400

The first thing is you should check to see if the 2 cooling fans are working. There is no cooling fan switch per se. The fans are controlled by the PCM computer through low and high speed relay switches located in the engine compartment fuse box. The PCM references to the coolant temperature sensor (ECT) to turn the fans on. Normally they do not turn on until the coolant temperature reaches 223 degrees.

To check the fans, take the car out for a run and turn off for a few minutes. With the AC in high and max cooling start engine. Both of the fans should be spinning either in low or high speed.

I agree with Blurr87 on the cooling system flush if it already has not been done and installing a 180 degree thermostat. Good luck!




Thrasher CAI, DHP v1.0 PCM,
3.25 SC pulley, CAIT GMAF, Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 TB,
TB spacer, MSD 8.5mm wires, Autolite 104s,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials

[StevePT]

I think all GPs, at least the early ones show a lot of fluctuation in the temp needle. They might have changed the gauge style over the years and made it less pronounced or changed the PCM settings and what it makes the temp gauge show. Might be why not as many people complain about this. I know on our 99 Buick Regal GS it's a C - H gauge and it always reads right about in the middle once the thermostat opens and never fluctuates.

Anyway, I think a cooling flush will help. If you didn't maintain your cooling system religously, you probably have dex cool "gel" in your radiator and the rest of the system. If the overflow hose was allowed to suck air in, it will cause the dex cool to gel and it's pretty bad for your system.

I flushed out my system after doing the intake manifold gaskets and got out a fair amount of "solid" matter on the first flush. I used a Prestone heavy duty flush that is acid based. It comes in powder form in a can with the cleaner and neutralizer.

[BNaylor]

Originally Posted by 1998GTP

Have any of you noticed any difference in performance? Thanks

Why do you mean by noticed any difference in performance?








Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.