hooked fan strait up to battery to make sure it works, it does. when i bought the car a few months ago, the coolant fan switch (lower left passenger side) wire was broke. bought a new harness and wired it in the best i could. tight area to get soldering gun. then checked the fan relay. it was melted together. ordered new fan relay harness from www.arizonatpi.com. took old harness off and wired, soldered and used that heat shrinking stuff. also bought new coolant temp sensor and new thermostat. i tested the old thermostat and it worked, but i bought a new one anyways. problem: still overheating, fan not comming on, and upper rad hose get hard and hot, and once the coolant in the resovoir filled up and was boiling hot. driving down the road, it seemed fine. but letting it idle for a few mins. in the yard, it over heats. i had some timing issues but i got that resolved. timing was way off. i know this is alot, but i would really appreciate the help. i've already did a search seeing if anyone had similar problems i am having but couldnt find any.edited: just went outside to crank it while its cold to see if it is circulating and it appears to be. it bubbles up alot to. also, probably running for 10 mins. and lower rad hose is very warm, rad cap is also very warm, upper hose is still fairly cool, both hoses under alot of pressure.

 

Your getting bubbles aka foam in your overflow? If there is bubbles coming from your coolant I am pretty sure that can be either a head gasket or air trapped in the cooling system due to earlier cooling parts being changed and replaced. I'd get a flush done and see what that does. Also, you might need a new radiator cap?

I am not 100% on these answers but they are some possibilities to them. Do you smell funky exhaust gases coming out the back of the car, that may at sometimes be white?

 

i'm getting bubbles at the radiator. i just bought a new cap and it helped some. the upper hose is not as hard and not as hot. still hot, but not as much. i let the car idle until it over heated or got up to 220 on the temp gauge and then turned on the heater to draw back some of the heat and to my surprise, the damn fan finally came on. the fan only runs when i turn the heater on. so that kinda tells me that i possibly have a sensor out. probably the coolant temp switch on the lower left of the engine as your looking down at it. when i bought the car, that harness to the fan switch was broke so i replace i wih a new harness. just wired it in the best i could. i'm taking a break from it today, but if anyone still has suggestion, please, type away. oh,and yes to your question about the smoke sometimes being white. the smell, not really sure. havent payed that much attention to it. i'll go ahead and do the flush myself.

 

well, today i replaced the coolant fan switch and flushed the whole coolant system. fan is still not cutting on. it only turns on when i turn the fan on. even when i kill the car, the fan does not kick on to cool the car. do i have a wiring issue? thermostat is opening

 

BUMP

 

Dude, I hate to say it in this way but it sounds like a bad head gasket. Have you checked to see if there is water coming out of your tailpipe? Also, have you changed out the fan motor?

 

the fan finally cut on, according to the gauge, at 240 degrees. i never let the car get that hot 'cause i didnt think that was right. i guess i can get a cooler coolant fan switch so it comes on earlier than it does.

 

My 91 runs at about 220-230 at the highest if I'm driving anywhere but the interstate or highway. I've got the fan set up directly to a switch that I can flip manually. I usually flip it on when the car gets to about 200 or occasionally I'll flip it on right after I start it up. Really quick and easy to set up the fan manually. I prefer it that way so I don't have to rely on it to turn on automatically.

 

i always had hot issues, i had my air dam, had an aftermarket 2800CFM fan, flushed it 1000 times, 160 stat......finnaly spent the dough and got a nice all aluminum racing rad,..........well now it gets no hotter than 180 or so with the a/c on


i dont know about the bubbles, before i say anything as drastic as head gasket i would rather look at the car and see how it acts and all, sorry i know thats no help to you

 

I was always told the fan is supposed to turn on at 195 degrees. I would just get a new fan switch or hardwire it.

Mine is hardwired to stay on all the time. What kinda shape is the air dam on your car in?

 

Yeah, my Trans Am is wired to have the fan on at all times the key is turned over.. but I'm going to rewire it to a manual switch the same as my Camaro. =P

 

And it still gets hot? I did notice you said it overheats while idling correct? I mean, if that's the case then I would say the airdam being damaged goes out the window.

Have you checked to see if water is coming out of your tailpipe? And I don't mean a small trickle, I mean alot of water.

 

What does it mean if water (straight water) gets blown out your exhaust?

A buddy of mine has an 87 IROC and his spurts water out, he said that means its running good? Because his dad is an old time muscle car guy and 40 years+ of mechanic experience building cars, trucks, go kart motor, quads, dirt bikes...everything, I have never questioned it as a bad thing...or else his dad would have told him..since the only things he knows is what his dad tells him.

Let me know more on water out of the exhaust.

 

Think you quoted the wrong person, bub. I was just leaving comments. I have no problems.

 

bump my car doing the same thing, how big a deal is it to replace a blown head gasket?

 

Most GM fan switches turn the fans at 220-225, off at 185-190. The bubbles could be either a bad head gasket or cracked head, or a bad waterpump impeller. Water out the tailpipe isn't usually bad, as exhaust from a well tuned properly running engine is about 90% water.

 

your guage could be off.
also my fans dont kick on til 225 w/ stock everything.
manual rigged switch to remedy this