Re: 1995 Pontiac Grand Prix Overheat Problems 3.1L

Removed Radiator Today. Found 20% surface area blocked with caked on dirt. Looking at flow area radiator was only about 60% efficient. Every row was effected in some manner. Also changing coolant temp sensor to see if thermister leaked out of sensor to cause improper signal to ecm which controls cooling fans. I will update you all if this problem is solved. Thanks for the feedback Steve.

MG

Mike Graves wrote:

Let me know .. mine normally runs 210-240 ...

| > Steven Dinius wrote: | >

| >> Don't run the damned A/C if it's a tall hill. I am amazed at people who | >> assume it's not old therefore the A/C is ok. Transmission cooler | >> should be | >> looked at if you have one or get one. Your car is 8 years old--and you | >> fail | >> to mention how many miles are on it. 100, 150 k? It's heading into | >> noman's | >> land now--repairs that HAVE to be done. Tranny, rebuild engine, at | >> least a | >> compression test or something. People treat their cars like dirt (not | >> saying | >> you, but I'm guilty). You should expect them to need repair. Especially | >> Harry : ) | >>

| >>

| >

Replaced Radiator today with a 2 row (which was not supposed to be made) GO Dan makes an aftermarket 2 row unit for the car. The factory radiator from GM is only a 1 row! It fit with no problems. I also set up a relay system that engages fan number 1 when the engine is started. This fan runs all of the time. The secondary fan only engages when the AC is started. The ECM controls the fan start and stop but Hayden makes a nice relay kit that you can install to bypass the ecm set up - Just make sure you install the jumper wire on the wire plug that goes directly to the fan assembly or you will burn up the ECM. Also - GM uses the Positive Power supply to engage the fan instead of the Negative Ground. This is different from most vehicles I have worked on. Also Hayden does have a 180 degree fan switch that comes with the kit that will turn on the fan at 180. I decided to let it run whenever the engine runs - use a jumper wire instead of the supplied switch. This way it is simple to disable if you live in an area that requires smog check 2, and makes sure the fan shuts off when you turn of the ignition switch. Also replaced the coolant temp sensor since it was out of range. This car was running at 240 before these modifications under loads or climbing hills. The flat land it ran at 210. 240 is way to hot for a vehicle to be running. I have noticed power loss at that temp, and stalls when the vehicle is stopped and restarted. GM did spec this engine to run hot, however I am working with my 26 years of parts knowledge to beat this.

I think I have solved this issue, however I have to take a hard road test tomorrow to confirm. I will post my results. Wish me luck

clevere wrote:

i would recommend putting a window screen in front of your ac condensor to keep all of the bugs out of there, that is the first thing i do when i purchase a new car, used car...keeps the condesor and radiator clean from stuff like that

Well.... problem solved. Replacing the radiator with a two row was the solution. The car runs between 185 - 200 degrees no matter what load. This is lower than the factory spec, however I did trick out one of the cooling fans.... radiator fan motors are much cheaper than engines. Anyway, for any of you that have overheat problems in the Grand Prix in this era I have found the solution. Run one cooling fan all of the time, replace the coolant temp sensor, thermostat, and go to a 2 row radiator core. Go Dan makes this one.....

WHO?? wrote:

Solution for internal radiator corrosion and scum would be RMI-25, sounds hokey but it works DAMN well and keeps your cooling system in wonderful condition.

Solution for scum on the exterior? Clean your car more often with a good waterblaster :-P

Oh and if you ever lose the lower skirt from your Fiero, don't drive on, replace it - they run a little too warm without. :-)

Nick.