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Hi, I have a 1980 Trans am with a 4.9L turbo engine with overheating issues. I took the car out to a car show 2 hours away for the weekend. On the way up I had no overheating issues at all for highway driving and city driving sitting in traffic. The Temp gauge ran between 180-200. On the way back home I ran into some overheating issues on the highway. About 30 minutes into my 2 hour trip any time I would reach an incline on the highway and have to give it more gas, the temp gauge would shoot up to almost 220. I would have to let off the gas and about a min or two later it would come back down to 190-200. As I kept diving it was getting worse to the point I was driving 85km per hour in a 110km per hour highway to keep the temp down. I eventually had to pull off the highway onto the side roads. From here I noticed a screeching sound from then engine. When I turned off the air conditioning (yes I know I should have done this long ago) the noise stopped and the car ran a lot cooler. Could a partially seized A/C compressor cause an overheating issue? I watched Eric’s overheating video and it did not mention this as a possible cause but seemed to link all together to when my overheating issues started.
Thanks.
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it’s possible that the belt is loose if the a/c and water pump share the same belt. It’s also possible that if the compressor is seizing up and making the belt slip that the belt is glazed. Either way it would be a good idea to check things out there. Go through the basics and make sure there’s enough good coolant in the system and that your rad cap and thermostat are good, that your intercooler (if you have one) is flowing properly.
You could also try retarding your timing a little bit and see if that solves the issue if the basic checks are all good. It wouldn’t be a bad idea to find a performance shop to throw a wideband O2 on it just to make sure your carb/pressure regulator is operating properly as well.
I suppose if the A/C compressor was trying to seize you could be working the engine much harder. This is kinda a reach though but worth checking into. Also some of those cars had thermostatic controlled fans that contained silicon oil. Have the fan off and lay it flat and all the silicon oil ran out. Then the fan fee-wheeled all the time. My cousin made this mistake and when he tried to pull a boat with his car it overheated.
Also, might be a good idea to pop in a new thermostat. Then make sure the cooling system is full.
Also, those second generation TA’s will all their grip would flex the radiator support and pop the radiator core loose from the end tanks. I had two TA’s, a ’78 and a ’79 and I always kept a spare radiator on hand. So check for leaks between the core and the tanks. Later on I learned that other TA owners put cross braces across the radiator opening.
Another thing I ran into while I was a TA owner was the radiator reservoir had a plastic tube inside and the tube got loose allowing the cooling system to suck in air as the engine cooled. A little hose clamp fixed the problem.
Thanks for the replies. The coolant level is good and there is no leaks. The rad cap looks fine as well. I will probably end up replacing both to be on the safe side as I am not sure if they were ever replaced.
This does indeed sound like it is tied to the AC . . . check the condition of the belt, look for significant wear, glazing, chunks missing etc. I would think that perhaps the compressor is having issues, or just that the belt isn’t tight enough, and with the added resistance of the AC compressor, it is slipping.
We’re missing the elephant in the room on this.
The condenser itself is designed to give off ‘heat’ in order to turn the gas back to liquid. When you have the AC running, the condenser will be giving off a lot of heat. If your air flow through the radiator is not at 100%, or the radiator is partly plugged up–It will make the car run hot.
Remember Eric’s video on overheating with the broken radiator? He removed the radiator and it was partly bunged up with leaves and other assorted trash between the radiator and the condenser.
Air flow needs to be checked as well. Not saying it couldn’t be any of the other issues listed—but with restricted air flow? You can get some oddball issues.
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Maybe teddy, but that screaching sound from the engine when the AC is on makes me think that the belt is the first thing to look at. If it weren’t screaming like a banshee, then I would think fan clutch, bad fan motor, leaves and debris, stuffed up radiator.
Do ’em both. Clearly the belt needs to be replaced. (once it starts to scream, it can glaze over…not good)
Get that belt seen to, and for good measure ensure the air flow isn’t being obstructed.
S-
Owners that bring cars to car shows fall into two camps. There’s the super modified camp where everything under the hood is aluminum or chrome plate and you don’t recognize the parts and there’s the everything looks original camp. I remember an owner who had a 1964 or ’65 Impala and he was proud of the fact that the car still had the original coolant hoses. I’m guessing the owner here falls into the second camp.
GM cars of this era didn’t have cooling problems. The radiators are big. But when you have a car that is 34 years old anything is possible. He could have the wrong gear oil in the differential and the rear axle was trying to be a solid axle. Drive on curvy roads and strain the engine. Or the differential could be going dry. He could have dragging brakes. I’d jack and check how easy all the wheels turn. I’d check how easy the A/C compressor can be turned manually.
Finally, if the engine has been left untouched all these years it could have a rusted away water pump or a rusted through head gasket. The radiator could need rodded out. Without knowing the maintenance history of the vehicle it is hard to say.
+1 on it being an AC issue. As pointed out if the AC is not working properly it can cause an increased heat load on the cooling system. Airflow is also a factor but I would think it would have been an issue on the way to the show as well if that was a problem. That is unless you picked up a piece of debris or something on the return trip. I would think you would have seen that however during your inspection.
I would be taking a closer look at the AC for starters. Outside of that, the information in this article might be helpful to you.
http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats
Good luck and keep us posted on what you find.
Thanks again for all the replies. Brakes are pretty much new (including the calipers) and the wheels spin freely by hand. There is no whine coming from the rear end and no leaks. I doubt it is the radiator being plugged up as it ran fine for my 2 hour trip up, the issue was on the way back (outside temperature was about the same). The car came with a booklet of well documented service that was done to the car. It has 36,000 original miles, the fan clutch was replaced in 2006 and since then it only had 5000 miles on it. The rad was replaced in 91 and since then the coolant was replaced in 2004, (at 29,000 miles) so changing out the fluid is on my list. However, it does note that the A/C compressor was just replaced in 2013. Anyway, thanks for the FAQ link on overheating Eric, I will read up on this to make my checklist. It will probably be a week or more before I post back on what I find out as I need to find the time between work to pick away at it. As soon as I have it figured out, or get stumped, I will post back.
No worries on getting back with us right away. In truth however, a vehicle with low miles can actually wear worse than one that gets driving all the time.
It does sound like the cooling system has been well maintained however. I’d be looking at airflow and the operation of the AC for starters.
Yes, I agree, a car sitting around develops its own set of issues compared to one driven all the time. I did have to drain out the gas and flush out the brake fluid, and still have to replace a few of the fuel lines at the rubber connections that are a bit spongy. Other than that everything looks good. It was garaged stored and for the most part the service done on the car was done well before it was needed (Trans flush, rear end gear oil change, etc). So luckily no other major bugs…so far.
I finally had some time to take a closer look. There is a lot to be said for checking the obvious first which I should have done in the first place. I checked the condition of the belts which are fine but did not check the tension on the belts. The belt that goes from the water pump to the power steering pump was loose. This belt looks newer than the other belts so it just looks like the new belt stretched out from all the driving I did. The a/c was just putting an extra load on the engine causing the belt to slip more so the a/c looks fine. So I just have to tighten this belt and everything should be good. Thanks for the help.
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