So before posting this I read up on the article talking about how Firebirds and Trans Ams overheat on the highway at 60+ mph because of the airdam. I replaced the airdam, still overheating. I did a custom job for an intake where there are two four inch vents sitting on the radiator that bring cold air in from where the foglights would be. Still overheating. I replaced the radiator and radiator cap. Still overheating at 60+ mph on the highway. With the old radiator it would blow water to the overfill tank, but not drain it back down. We have yet to have the same problem with the new radiator. There is no thermostat, and the electric fan is hardwired. The fan is also new.

There is no chocolate milkshake in the oil, nor is there coolant in the transmission fluid. There is nothing but coolant in the radiator.

No obvious coolant leaks, small oil leak. No obvious transmission fluid leak.

Am I missing something? I don't know what else I should be replacing.

Also: By overheating I mean 240+ degrees. Sometimes as high as 260.

Be forewarned, I'm still new to working on my car.

EDIT: My car is an 1985 Trans Am with the LB9.

 

you should put a thermostat in it, coolant can actually flow too quickly through the motor and not pick up enough heat. could also be your waterpump. is the water pump old?

 

yes,I second that,put a thermostat in it,is your water pump leaking out of the weep hole on top of the pump?If so replace it ,maybe your radiator has crap in the finns pull your radiator out and power spray it.

 

The water pump is not weeping, and I am not sure how old it is.

The radiator is brand new.

It was overheating before the thermostat, but I assume that it could've been bad and that could be part of the problem?

 

put a thermostat in it and get a high flow water pump
oh and check that your radiator hoses aren't colapsing my lower hose would flatten out all the time not allowing any coolant to get through.

 

What article did you read about firebirds and trans ams overheating on the highway???

My car runs the best on the highway, because the airdam picks up air, and guides it through the rad. What did you "replace" the air dam with?

My car has a single electric fan to a manual switch. Ive driven it on 25* celcius days in 20 minutes of traffic. Stock rad, and a 355 10:1 comp engine. It went to about 220* in the 20 minutes of stop and go traffic, but as soon as i got moving about 25+ mph, it cooled down right away. I dont need my fan on the highway because the airdam works so well.

 

What sort of thermostat should I get here in Oregon? The 170? Or does it not really matter?

I'll probably just replace all the hoses and get a high flow water pump, along with some sort of thermostat.

 

These smog computer controlled motors were designed to run hot. 240 isn't that bad but 260 is getting up there. Thave you ever monkeyed with the temperature gauge? Could it be reading high?

 

I'd go with a 180 or 195
the best thing to do is find out what thermostat your car had in it from the factory.

 

http://www.gmtips.com/3rd-degree/dox...overheat-1.htm is the article. I replaced it with a piece of sheet metal shaped to look the same as the stock one.


I don't know how. I never have before. How would I go about seeing if it is reading high?

I'm going to replace the water pump with a high flow one tomorrow, along with a hose replacement and thermostat replacement. Hopefully I will be ordering an actual airdam and accessories tomorrow as well. I'll let you guys know how it goes.

 

if it doesnt overheat at idle I would say airdam.depending on the gauge of metal ,but I would guess the metal is flexing at speed and the air going under .
Get a new airdam ,should fix it

 

Just to let you know, I would check the upper radiator hose with no thermostat in and see if there is coolant in that hose. Even at idle, you should feel a crap load of water in the upper hose. If not, raise engine speed a bit and then check hose. If no water, you got water pump issues, if there is water, then clean out your radiator. I had a bad napa water pump and it wasn't leaking which really sucked but I replaced the pump and now everything is cool.

 

You said your electric fan is hardwired. Make sure you don't have your polarity crossed. These electric fan motors will run in either direction. You could be pushing air into the radiator instead of pulling it through. If it is reversed the fan will be REALLY loud and you will feel no air being directed at the motor. In regards to the temperature gauge, if you haven't replaced your instrument cluster it's probably working properly.

 

when i put a new radiator in and replaced the hoses the bottom main hose had a spring running through it for strength.

 

had the same problem when I first got the car, haha.. I had alot of problems with it... and it would get damn near 260 on the highway.. and would be Ok On the streets.... Look Underneith and check for it hanging or Cracked in half...

I ordered a new one from GMPARTSDIRECT.COM .. I also hear there are Bigger ones you can use too...

 

He already replaced the airdam.

 

So you did or didn't replace the airdam? Your first post said you replaced the airdam but then you said you custom fabricated something.

 

I said I replaced the airdam with a piece of sheet metal shaped like the stock airdam. I assumed that it was understood. My mistake.

I have shaped a piece of sheet metal to replicate the airdam that comes stock. I have made a custom intake by taking 4' pieces of dryer hose and connecting them to the foglight holes and up to the radiator. I have replaced the radiator and the radiator cap. I will be replacing the radiator hoses today.

 

See what happens when You skim thru the post.. Sorry about that, I was reading and In a rush to get out the Door for work this morning

he probably did replace it, but with one of his own custom Design..I wish I had those metal benders, I would make a Mega Dam, But without the bender it would Look Cheap, and Crappy.. So the stock replacement would do...

 

My initial guess would be...You only needed a new thermostat, as long as the hoses themselves aren't collapsing. Without one, the water runs through the radiator too fast to cool down enough to do any good. You mentioned replacing it at an older point...the thermostat is bad?

 

Theres nothing but antifreeze in there? Put less antifreeze in and more water like 70water 30antifreeze. Is there a a/c condenser or transcooler sitting in front of the radiator? any crud on that or radiator? If you havent already flush the radiator.

 

First off put a thermostat in the car, like said a couple post above if you remove the thermostat, coolant runs too fast through the radiator to properly cool down. Stock was 195* i would put a 180* as these cars ran too hot from the factory for my liking.

Next the air dams on these cars did a great job of keeping these cars cool, take off whatever you made and go back to stock there is NOTHING wrong with them other then they get ripped off from bumps.

Do those first then check back with us.

 

There is no antifreeze, I never said there was. Currently I'm doing 100% water because it really isn't getting that cold. The radiator is brand new, and has already been flushed once.

Will do. I really didn't want to spend $70+ on a new one, but okay. I just bought a thermostat today, and I will hopefully get that in. The reason I don't have a stock airdam is because there wasn't one when I got it, and I didn't have the money then to buy a new one.

 

junkyard = cheap air damns

 

Brand new airdam on ebay= $35.00+ Shipping

Check item #300212733512