Cooling system, feeling the heat..

**98GPGT2D** · 07-02-2011

Hey guys and girls,

GF and I were out driving around in the heat today (about 100F without the humidex factored in) and the Grandprix gets pretty hot. A while back, I replaced the temperature sending unit AND thermostat, because the gauge in the car read inaccurately. After replacing the sending unit and t-stat the gauge still read inaccurate, so I plugged my Mac Tools scanner into the OBD port and monitored the temp real time. The scan tool shows the car running properly at 97-100 degrees, with the gauge cluster showing about 70 degrees. Today, driving around the city, the gauge showed the car running at a tickle under 100 degrees (keep in mind the gauge reads inaccurately, so I dont know exactly what that converts to..I'm going to have to monitor it again..I'll do that after I post up here..

My issue is this... even with the AC on, the cooling fans out front turn very very slowly. I could likely stop the fans with my hand if I really wanted to try. (a $10 bet might get me to do it tho...lol) Is the cooling fan on a 2-speed circuit? Im thinking I have an issue, because you dont even hear the fans come on, and the temp rises quick at stoplights and slow driving.

Jay

**Bob Padilla** · 07-02-2011

Originally Posted by 98GPGT2D

Hey guys and girls,

GF and I were out driving around in the heat today (about 100F without the humidex factored in) and the Grandprix gets pretty hot. A while back, I replaced the temperature sending unit AND thermostat, because the gauge in the car read inaccurately. After replacing the sending unit and t-stat the gauge still read inaccurate, so I plugged my Mac Tools scanner into the OBD port and monitored the temp real time. The scan tool shows the car running properly at 97-100 degrees, with the gauge cluster showing about 70 degrees. Today, driving around the city, the gauge showed the car running at a tickle under 100 degrees (keep in mind the gauge reads inaccurately, so I dont know exactly what that converts to..I'm going to have to monitor it again..I'll do that after I post up here..

My issue is this... even with the AC on, the cooling fans out front turn very very slowly. I could likely stop the fans with my hand if I really wanted to try. (a $10 bet might get me to do it tho...lol) Is the cooling fan on a 2-speed circuit? Im thinking I have an issue, because you dont even hear the fans come on, and the temp rises quick at stoplights and slow driving.

Jay

Slowly dying fan motors and or relays on their way out? Either way its just a guess and or a free bump for ya. I'm feeling the heat too bro. I'm in Houston ugh.

**98GPGT2D** · 07-02-2011

here's what I know now...when the cooling fans turn on, they turn on at a slow rate (ie, they turn slow) Turn the AC on, and they turn at a faster rate, as they should, due to the higher heat load of the AC system. Is there a way that I can wire it up to have the fans come on at the High rate all the time (ie with the AC system off)

Jay

**QUICKSILVER462** · 07-02-2011

I think I would start and make sure that it has the corrct amount of coolant, no air in the system, and that the radiator is in good shape before I would start to modify the fan circuits. The computer controls the fans to maintain the proper pressure on the high side of the a/c system also, along with cutting the fans out all together over a certain mph to take load off the engine and charging system.
Also make sure there are no abstructions infront of the radiators which can hamper low speed cooling performance. If the everything checks out ok with the scan gauge and the system is under pressure and not boiling, there really is not a problem.
These engines are designed to run much hotter than the "old skool" engines that liked 180f.
If my 68 Nova ever got to 210 in traffic it was time to pull over and let it cool down!

**98GPGT2D** · 07-02-2011

Cooling system checks out. Cap is good, and the system pressure tested good. The condenser fins are straight and not obstructed. No bug nets or screens infront of the cooling package. The coolant seems to peek at about 108 or 109 degrees, or 228F

Jay

**cerick08GP** · 07-02-2011

Originally Posted by 98GPGT2D

Cooling system checks out. Cap is good, and the system pressure tested good. The condenser fins are straight and not obstructed. No bug nets or screens infront of the cooling package. The coolant seems to peek at about 108 or 109 degrees, or 228F

Jay

FWIW your cooling system seems to be running just as designed. But now that we are in the thick of the summer heat you are noticing what many others have, these GPs run hot. Maybe a bit to hot in some peoples opinion. My recommendation to you is to have the PCM fan settings tweaked and 180F thermostat if you feel more cooling is needed. Keeping in mind a warm engine is an efficient engine, more cooling quickly turns into less mpg.

Personally I just make sure my fluids are topped off, and I do remove my engine compartment seal every summer. The engine compartments on GPs get blazing hot this time of year and make me a bit nervous, IMHO removing that seal keeps things a bit cooler and helps it cool down faster after turning it off.

**Bob Padilla** · 07-03-2011

Originally Posted by cerick08GP

FWIW your cooling system seems to be running just as designed. But now that we are in the thick of the summer heat you are noticing what many others have, these GPs run hot. Maybe a bit to hot in some peoples opinion. My recommendation to you is to have the PCM fan settings tweaked and 180F thermostat if you feel more cooling is needed. Keeping in mind a warm engine is an efficient engine, more cooling quickly turns into less mpg.

Personally I just make sure my fluids are topped off, and I do remove my engine compartment seal every summer. The engine compartments on GPs get blazing hot this time of year and make me a bit nervous, IMHO removing that seal keeps things a bit cooler and helps it cool down faster after turning it off.

Don't forget about that horrible engine cover as well. Iirc it retains heat.