My 89 GTA will start to get hot when it's idling, but when it's moving its fine. The temp will stay around normal as long as she's moving, but say sitting at a traffic light too long or stuck in traffic she starts to get hot. However once I start moving again the temp returns to normal. The car isn't using antifreeze (I filled it up awhile ago and it still shows full) and when you pop the radiator cap (I replaced th stock cap with a pressure release one) it seems to be circulating fine as well (when idling it's a bit slower, but I feel that's expected).

Another thing I have noticed is I think the radiator fan isn't coming on as I cannot hear it when the car is idling at a light. Also I am not really getting any heat from the heater. I have been told it may be the thermostat is either not working or it's completely missing all together. I also have had the engine washed too.

Any help in figuring out what could be my problem would be welcomed.

 

When I read the title to your thread the 1st thought was non working fan, missing fan, no fan shroud..

Being you said you don't hear the fan running, I'm bout 75% sure that is your prob.

See the air flow while driving, comes up from under the car, the air dam directs it into the rad. and that keeps it cool.

As you slow down or stop, that air flow is gone and your fan must pull enough air through the rad. to keep engine running cool.

 

how hot does it get? if it isn't bubbling over, it's not "overheating"..
the fan will come on at something like 235 degrees in stock form.

 

Well it goes past 220 and onto the I guess you can say 235-240 ish? I don't really know because the gauge isn't clear on that. I will say that I am getting very little to no heat from the heater however. I don't see smoke coming from the car either (a sign of a possible blown head gasket). Also there is not antifreeze in the oil, and it is circulating (as said before I can take off the radiator cap and see it flowing). I just recently bought the car and most I have had before this one has never went as high in temperature. If you say it's normal I'll just keep an eye on it. But what about the lack of heat?

 

Let the car idle up to temperature, open the hood, is the fan running when it gets hot?

Turn the AC on, does the fan come on? (Override mode, fans auto run when AC is engaged).

 

is it possible that the temp gauge is reading wrong? does it seem like it is extra hot under the hood when it's "overheating"?

the lack of heat out of the heater could be a clogged heater core.. are both heater hoses under the hood hot when the engine is hot? if not, then the water isn't flowing thru it for some reason. it's also possible that the heater core isn't even hooked up due to the previous owner not wanting to replace it when it started leaking.

 

She has not over heated yet. The only time the temp rises is when idling. Say at a traffic light. And it was about 245-250ish at its highest. When the car is moving (I live out in the country so its very open out here) It will stay very cool. Say around 160-200ish. And the heat did work at first, but then it slowly tapered off until now its completely gone. I popped the radiator cap off and theres a lot of gunk and crud floating in the antifreeze. Brown sludge and build up most likely.

I was told I should pull off the radiator hoses and the two bolts in the water jacket on each side of the bottom of the block then stick a hose in the thermostat opening and flush the block until it comes clean. Does this sound like a good idea? I would like some opinions before I do this.

I am going to just replace the radiator, water pump, thermostat and heater core. They are probably original so I imagine they are clogged full of buildup.

 

I'm wondering if you even have a thermostat. If you did then the engine temp would stay around 190-200. If the water temp goes below a certain temp, then I believe the computer (ECM) puts the system into open loop, i.e. full rich. I agree that the heater core may be bypassed. That was one of my first projects; replacing the core. If there's a lot of crud floating around in the radiator, the temp sensor could be covered in crud as well. I think you're doing the right thing by replacing the radiator. But you will see these other parts (thermostat, fan temp sensor) when you remove the old one. Oh, and use distilled water rather than garden hose water. No minerals means no crud or sludge.

 

Actually that's what I was told as well from a co-worker of mine. He's a maintenance tech at my plant (used to work as a mechanic at a Chevrolet dealership before that). He too felt there may not even be a thermostat in the car either. I have seen the temp fall to 150 and stay there when cruising on the expressway. At least the air dam is functioning correctly.

 

"I am going to just replace the radiator, water pump, thermostat and heater core. They are probably original so I imagine they are clogged full of buildup."

And while you're doing all that and finished, add some straight Prestone anti freeze...about 50/50
mix with distilled water.

Your cooling system will thank you!

 

I am having this same exact problem. Before you go through the pain of that. The fan if electric has two relay switches. One is by the driver-side firewall the other is on the passenger side on the front. I have replaced the water-pump, thermostat, new anti freeze, and a relay switch. The problem according to the book I have an 86 service manual states the 6 bangers have a sencor that tells the fan to kick on. The 8 bangers use the ECM. I too have no heat and she looses power and doesnt seem to be performing well at times. This is the trouble shooting in the book Which I have yet to do myself. If these images dont work I will have them in my photo gallery.




Cooling fan 1

 

I had a very similar issue until I flushed the system. You cannot believe the amount of crap that came out of the block! First I did a regular water back flush and then I ran some Blue Devil in it for a week or so. Once it was nice and clean, I filled it with 70/30 and a bottle of Arctic Ice. She's cool as a cucumber now.

 

Yeah I feel that's the issue I am facing as well. 20+ years of crud and buildup inside the water jacket and radiator. It's just time to get that crap out and run some clean antifreeze through it.

 

Just a side note here...If you have a original radiator and about 80 bucks to spare, take the radiator out and take it to a rad shop and have it "rodded out". They take the tanks off the sides, boil the core, and run thin rods through the passages and re-assemble. Good as new.