rmj254

I own a 1986 Trans Am. It has a non-original 305 (I think) that overheats badly. I have changed the thermostat and it didn't help. I need some solutions to this problem. Any help will be appreciated.

zach

Make sure the electric fan is comming on.

Mark A Shields

Well, there could be several things.

When does it overheat? Traffic/highway? both?
Still have your air dam?
Make sure the lower radiator hose isn't collapsing under high rpms.
Be sure the gauge is reading accurately.
What temp stat did you get by the way?
I'd lower the temp at which the fans come on, stock setting is like 220*, these cars are designed to run warm for emissions.
Make sure you have not clogged exhaust.
Be sure you're tranny fluid is filled.
Make sure there are no restrictions in front of the radiator.
Maybe try replacing the radiator cap.
Open the rad. cap when you first start the motor while cool, let it warm up, when the stat opens make sure the water pump is pulling/sucking the water down.

Let us know how it turns out.

rmj254

I have replaced the thermostat with a 190 degree unit. The car doesn't have a driveshaft so it is overheating in the driveway. I crank it up and let it run and there is no water flowing. The fan will not come on, but there is still no water flowing.

rmj254

Also, the person that owned this car before me (for some stupid reason) rigged the fan to be switched on by the person driving the car. I don't why someone would do this, but they did. Do I need a new fan or should I just rewire the one I have?

Boosted GTA

One thing that i notice alot of people havent recommended to check is to see if you have a blockage in your radiator, or even a restriction. very big cause of over heating, especially in older cars.

Redarrow1

No water flowing. I think you answered your own question. My guess would be you have a bad water pump or installed the thermostat backwards.

1987fbd

Well wiring in your own switch is not that bad of an idea. Sounds like the last owner had the same problems, thus the manual switch on fan. From what you have said, I would have to agree with the last two here. Sounds like thermostat is in backwards #1. Or #2 your water pump should be flowing if its not its shot. With engine cool take cap off and rev the engine a little and watch the water and see if it swirls. If it does your ok if it doesn't you need to change it. Also make sure that fan switch is on if it's manual. I am sure it doesn't have a thermostatically controlled unit on it. Also maybe your cat or your muffler is plugged check that also

Good luck!
Remember these things like to run at 220 or better in some cases.

rmj254

There was no water flowing before I installed the new thermostat, so that is not the problem. The fan worked when I got it, but doesn't work now. I am going to wire it back like it was supposed to be, so that I don't have to deal with turning the fan on and off manually. I ran the car one time and the coolant boiled over, so I think it was probably running a little over 220! It also can't be the muffler or cat, because there is not one on there.

Boosted GTA

If you have no water flowing before you replaced the thermostat, and now you have no water flowing AFTER you replace the thermostat, the thermostat is NOT the problem. Water not flowing is a very good reason why you are over heating, even though you are sitting still. Check your water pump!!!!!!

You said your car was over heating before you even did the fan switch and the new thermostat.


You are boiling over cause your pump isnt circulating. Even do a flow test on the pump.

1987fbd

I agree! Also if your fan is not running, then even if the water pump is working and the therm is good you will still overheat. Got to have a fan that will turn on.

dale davidson

how does one go about flow testing the WP?
thanks

gpierce

I don't think I've ever heard of a good way to test one. How do you know there is no water flowing?

Assuming you have a belt on the pump and it is turning I would just remove the top hose start the car and see it water comes out. If not, either you have blockage somewhere in the system, or your pump is broken. Replace it.

GP