AxlCrucifix Posted July 4, 2008 Report Share Posted July 4, 2008 Hey guys. I've got the 2.8 MPFI in my '89 Grand Prix, and its been overheating lately. I put in a new thermostat since the coolant wasnt cycling through, now it is. I notice that the fan will only kick in when the temp hand is 3/4 of the way up. Is there a reason it is doing this? I tried swapping out those big square fuses under the hood for the primary and secondary fan controls, and still no use. After driving for a bit, when it is parked and idling, it will go up 3/4 of the way, the fan kicks in, then it goes to a width of the hand above half. Fan shuts off, and the cycle repeats. Any suggestions? Thanks! Quote Link to comment Share on other sites More sharing options...
per0781 Posted July 4, 2008 Report Share Posted July 4, 2008 when you replaced the thermostat, did you bleed all the air out of the coolant? Quote Link to comment Share on other sites More sharing options...
AxlCrucifix Posted July 4, 2008 Author Report Share Posted July 4, 2008 no How would I go about doing that? I know there is some sort of special coolant fill procedure, but I'm not sure what it is. Quote Link to comment Share on other sites More sharing options...
AxlCrucifix Posted July 4, 2008 Author Report Share Posted July 4, 2008 Pardon my ignorance, but what would air in the coolant have to do with the fan not kicking in when it should? Quote Link to comment Share on other sites More sharing options...
meltboy1 Posted July 4, 2008 Report Share Posted July 4, 2008 there is a little screw on top of the water outlet housing... follow the hose from the radiator to the engine near the throttle body. Run the car a few min to heat up with the radiator cap on and loosen that screw a little bit, but be careful cuz I think it's brass, I broke mine on the TGP. Wait til only water comes out in a stream, not spurts then top it off, that's pretty much all I did when I put my radiator back in. Quote Link to comment Share on other sites More sharing options...
meltboy1 Posted July 4, 2008 Report Share Posted July 4, 2008 air would make it so that your coolant wouldn't be doing it's job to the fullest. Quote Link to comment Share on other sites More sharing options...
AxlCrucifix Posted July 6, 2008 Author Report Share Posted July 6, 2008 ok cool ill try that but would that have any effect on the fan not cutting in until it gets really hot? or does the fan only cut in at high temperatures or what could it be the heat sending unit or whatever its called? Quote Link to comment Share on other sites More sharing options...
mtnrider1 Posted July 6, 2008 Report Share Posted July 6, 2008 Air in the system causes hot pockets in the system also it can give false info to the coolant sensor .That being sead their are three major causes on this car in a overheating problem. 1. cause bad radiator cap wot hold pressure 2. If car has high mileage poss plugged radiator IE bottom cores filling up with crap 3 Intake manifold leak Quote Link to comment Share on other sites More sharing options...
AxlCrucifix Posted July 8, 2008 Author Report Share Posted July 8, 2008 i bled the air out and it seems to be maintaining a good temp now driving its about 1/4 of the way idle it sometimes gets as high as half, but never more and this is in 30 degree celcius weather too is half temperature at idle in hot weather still too much? Quote Link to comment Share on other sites More sharing options...
meltboy1 Posted July 8, 2008 Report Share Posted July 8, 2008 half temp in hard city driving is not bad... 30*C is what, about 80-90F? if that's the case I would say your system is runnin good. Quote Link to comment Share on other sites More sharing options...
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