Ok here is the deal. Last night i was driving home and i noticed at stops my idle was pretty high and getting higher. well i look at the temp guage and its almost at 260*. so i pull over and shut it down. now the guage is not screwed because the overflow bottle was spewing steam and the radiator was dumping all the coolant into it. I have noticed that lately the car will overheat but then start cooling back down , never getting near redline. But it has been dumping into the overflow bottle whenever i shut it off. What is the deal. I just put on a new water pump about 3 months ago. i replaced the radiator fan about a month ago. new thermostat. New heater diverter valve. and today i just put in a new radiator. still overheating. now i did notice that the cooling fan was not on when i shut the car down and normally it would stay on for a few seconds after. that is why i replaced it. when i turn the ac on it comes on but when the engine was overheating it did not. could this be the problem and if so how do i fix it. Please help i live in Texas and i dont want to kill my car.

 

Maybe you got a nice big air pocket in the cooling system. I would fill er up and turn er on and watch to make sure there is flow in the system. Next, I would make sure the fan/fans come on when they are supposed to all the while periodically looking on the ground for drips. You got an air deflector on that thing? Don't stress, you'll figure it out...

 

no, when i replaced the rad i ran the system and burped all the air out. the only thing i can think of is that the coolant fan is not coming on during normal running and that is causing the rad to not work. but it comes on with the ac on. maybe the fan switch is bad, i really dont know too much about the fan system. no coolant leaks though. and it overheats in slow city driving.

 

Sounds like a fan problem... I'd let it run and sit there and wait to see if the fan does come on by itself. If not try grounding the fan switch wire.

 

I def sounds like a fan thing... when my car didnt have an air damn, and the heter core was busted..i woudl drive around the city and my car would overheat and when i would pull over the antifreeze would boil over i found out the fan was shutting off at about 240. then i fixed the heter core and put in a manual fan switch and it wouldnt over heat in the city anymore...just on the highway at high speeds and the sir damn fixed that so it def sounds like the fan. either put in a manual switch or buy a new coolant fan switch that turn on at about 220 ish and shuts off at 170ish

 

yep, sounds like the fan switch. I have had to change mine twice. The dam things just dont last for some reason. Cheap fix though, probabley could of saved you some $ if you would of changed it first.

 

that sounds about right. what switch do i get. does anyone have a part #. i would actually like one that switches on at a lower temp like 195. thanks guys.

 

Just ask for the fan switch, they should know what you need. As for the temp ? I think that they are all the same. Hope it works out for you

 

There are fan switches that allow the dual fan cars to engage the secondary fan earlier. So I would assume that there is something available for single fan applications as well.

 

GM MAKES A FAN SWITCH THAT ENGAGES FAN AT 190deg.PART # IS 3053190.DONT KNOW IF STILL AVAILABLE THOUGH.

 

Standard makes a switch (P/N TS-136) that comes on around 208 and off around 188. I just put on in my TPI car. Don't know where they are located on a TBI car, but it's likely the same size. Search around for some verification. I bet you'll find somebody who used a grand national switch (ts-136) on a TBI.

 

Kick ***. you guys rock. it was the fan, its not coming on and that is causing the overheating. man i spent a lot of money to find what the source is. still dont know what the prob is thouht. did everything that the manual says to check for the cause and im thinking it may be a disconnected wire. ill check into the lower switch. i also heard that you can use a switch off a 3.8 turbo buick or something like that, not sure read that post a long time ago. ill figure it out and let yall know. i will definitely be able to help people track down cooling problems after i fix this one. thank *** for the wiring diagrams. and thank all of you for your help..

 

That's the switch I just gave you a part number for

 

Glad you figured it out. Too bad though about spending so much money. At least the rest of your cooling system is all new and shouldn't give you any problems for a while!!

 

Hey wow...im having the same problem..i was about to go out and buy a new thermostat... but my situation soulds way to similar to this to not check the switch...

 

I just had the same problem with my maro. the fan switch is located on the pass side head in between 6-8 cylinders

i used a gp sorenson part # fs6 got it @ advance auto

turn fan on @ 220 shuts down @ 205

and i use a 180 stat

if you go any lower than that the fan will stay on non stop
on the temp setting for the switch .

thats abit cooller than stock
the stock switch comes on @ 238 and shuts down @ 222

i work at advance. so i went on a search to find one that would turn the fan on @ a lower temp. the fs6 is the best one to use in my opinion.

 

how much did that switch cost at advance auto? im having the same problem also, im gonna try changing it...

 

Is there a difference between a TBI fan switch and a TPI fan switch?

 

shouldnt be.. exceopt fro losation maybe... if you mean manual then no unless you have duel fans which i think most tpi's come with then it would be your choice to hook up both top one switch or one to two switches or one manual and one automatic etc

 

I'm all but certain that the fan switch for a TBI car is the same as the fan switch for the secondary fan on a TPI car. Actually, scratch that. I'll go ahead and call it certain...

 

in 1989 the tbi motor got a slightly lower temp switch than the tpi motor.
like 233 vs 238 on temps.

 

Also the corvette got a even lower temp switch that controls the left hand fan i do beleive that the switch closes @ 210. Also the aux fan switch for a buick GN that sit in the intake under the throttle body closes @ 200 degrees.



HTH

Patrick Broughton

 

Guy I bought my car from said that it kept overheating. I think I'll give this a shot and see if that solves the problem. However I guess I better get all the stuff from around it in the garage first!