cxxm

Just for information

I have a 1984 Trans Am 305 L69 (Carburetor) 5 spd with the stock aluminum/plastic tank radiator and electric fan.

My thermostat is 195 F degrees and new to me will stay open if it breaks instead of closing like the older ones. I got it at Schucks (PA 4867024 (7200195)).

My fan was kicking on sporadically causing me to over heat. I installed the Hayden Electric Fan Control (HDA-3651) from Summit for $45.91. I placed the temperature sensor up on the intake manifold (Edelbrock 2701) near the thermostat. I really like the Hayden relay, because it allows you to adjust the sensor from 160 to 210 F degrees to kick on the fan. I also got an LED light from radio shack and attached to the power wire on the fan. This way I know when the fan kicks on when driving down the road. I set the fan to kick on at 210 F.

Things got better, but when I drove down the highway it started going to 230 F degrees. In fact the temperature was all over the place. Up and down all the time. I did find the rubber flap underneath the car that covers the headlight access covering 25% of the radiator. It helped a little when I removed this, but I was still having the wide range of temperature fluctuations.

Next, I ordered the Direct Fit All Aluminum 82-92 Radiator (SUM-380455; $289.99) from Summit that is suppose to have twice the cooling capacity over stock. It was a beautiful radiator. However it is not a direct fit without a lot of modification. This radiator barely fits into the car. The petcock is on the wrong side (driver side) and runs into the power steering cooling tubes. Basically, the tanks are too fat and do not allow the radiator rubber mountings or top radiator plastic cover to fit over it, which causes the electric fan not to fit correctly. You’ll have to do a lot of modifications, cutting and buy mounting pieces to make it fit. I sent it back not wanting to spend weeks to make a radiator fit.

I bought a stock replacement radiator (Aluminum/Plastic Tanks) from Autozone. It is a Spectra 433918 (1 row, 26 ¼’’ x 17’’x 1 ¼’’ core size) Radiator for $91.99.

Things got better. The car temp was staying at 212 F or lower. Of course the outside temperature was only in the 50-60 F. Also, going down the highway the fan was still running lot. I thought driving down the highway should have plenty of airflow with no need for the fan.

One day the outside temperature hit 93 F and the engine quickly went to 220 – 230 F. I notice the car would get hotter driving down the highway at 55 mph than going 20 mph through a neighborhood.
I read the normal operating temperature for an engine is between 180-210 F. My factory temperature gauge shows 100, 220, 260 marks. So I’m thinking that the factory temperature would be at 220 F. There might be a difference in my temperature reading due to running the sensor in the manifold than inside the block. I am running an aftermarket mechanical temperature gauge that I got from Schucks due to the stock electric gauge not working.

The 1984 Trans Am does have some small vents in front for some airflow through the front to the radiator, but not enough to cool the engine down. I also have the fiberglass Ram II hood that pushes air in through the top.

I did some research and found that the airflow is supposed to go underneath the car and is funneled up into the radiator. Some cars have a sort of plastic air box in front of the radiator. My car was missing the side rubber flaps that cover the head light access and help funnel the air from the vents. I installed both these pieces.

Now the most IMPORTANT piece is the plastic spoiler that is directly under the radiator. It hangs down a few inches. I found my spoiler was missing several inches being broken off probably from parking over sidewalks. I found a good one at a salvage yard for $5. From what I can tell it funnels a lot of air into the radiator instead of letting all of it go underneath the car.

I noticed a difference right away. It was 60 F outside. It took the engine longer to heat up to 195 F. When I went down the highway the fan did not kick on at all like it had done before. In fact it stayed at 190 F at 55 mph.

I took the car on 100-mile trip up and down hills at 65 mph. It was 80 F outside. The car stayed at 190 F and the fan never kicked on once all because of adding the plastic spoiler under the radiator.

The fan is only kicking on at idle or driving around town with the constant starting and stopping. It reaches 210 F, the fan kicks on and cools the car down to 190 F. It cools down even faster with the spoiler.

I’ll post more information when the temperature hits 95-100 F outside.

camaronewbie

Just so you know - that air dam does not help force air up and 'into' the radiator. In reality, it creates a low pressure point behind the radiator, and thus air is sucked through the radiator as it's naturally trying to fill the low pressure area. There was never anything designed within a 3rd gen to force air into the radiator from the front.

The air dams make a huge difference in speeds above 35-40mph - glad you solved your issue!

cxxm

Thank you for setting me straight. I just got my car in November 2009 and still learning. I see I came to the right place.

85 Russett T/A

Excellent post, cxxm and camaronewbie...

I just got my 85 T/A a few months ago, and just did a tune up (cap, rotor, wires, plugs, water and thermostat). I drove it from MD to NY where my brother helped me, and I noticed in the hills in PA the temp went up a little past 240. After we changed the water and thermostat, the temp is better, but still seems to want to stay around 220 (the Stant Thermostat is 195). I thought that maybe the needle is off or some sensor is just old and therefore something is inaccurate.

I had read somewhere about a "chin spoiler" being there to create a low pressure area behind the radiator, but my car doesn't have one. I definitely want to try this out. Any suggestions on where to get one, or is a junkyard the best place?

cxxm

You can try www.classicindustries.com. They have a Firebird/Trans Am catalog. On page 396 it shows a front end center deflector (G8922) for 82-90 for $42.95.

Also for my update, it hit a 100F and my car never got over 210F going down the highway (65 mph), but the fan did kick on once and a while to give it a little help cooling. It did not stay on very long. The car hovered around 200F most of the time. The deflector, air dam or spoiler solved my problems.

Lastly, I moved my temperature sensor location from the intake manifold into the passenger head where the sensor was for the car temperature guage. I did not see a change in temperature ranges between the two locations.