Alright, 91 RS Camaro, car overheats when the a/c is on, when the a/c is off, it still runs at 200, which is too hot for me. The fan is constantly running and the radiator is full, just replaced the thermostat, heard the coolant canister boiling the other day. Think its a bad water pump? Any way to test this? thanks

5.0L

 

anyone?

 

Step 1: Is the air dam in place and in good condition?

 

yes it is

 

200 degrees in the summer time even with a cooler thermostat (stock is 195) and a lower fan switch or setting is about normal for an iron SBC, ESPECIALLY so in a 3rd gen F-body. So it sounds like the cooling system is working, but is not able to meet the demands of the AC condenser. You either have an airflow problem or a radiator problem.

I would recommend replacing the radiator with a much better unit like a Griffin (or Be-Cool if you're rich) - the stock replacement stuff will work, but will not provide any additional cooling. Replace the stock single fan with a dual unit from a 4th gen F-body, and completely seal the front of the car that leads the to coolers with foam tape, and that includes above and below the radiator and condenser, and between the two. Seal the fan shroud to the radiator. You want the eliminate any escaping air, as it lowers the cooling potential.

3rd gens have terrible airflow problems. But with the above mentioned items, I dropped my summertime coolant temps over 25 degrees!

 

alright, taking all of this in consideration. dont think it could be a bad water pump? I will check the following. Also if you didnt know, you can get an Aluminum radiator for about $100.00 for the 3rd gens from 1-800-Radiator. And Ill try to replace the stock cooling fan with a dual setup. Thanks for the help, will get updates.

Car has 160 thermostat

 

Other than seal failure (weep hole leak) the SBC water pump design is tried and true. VERY RARELY do they fail to the point of being unable to push any water. 99 times out of 100 they're replaced for leaks.

If you're that concerned about the pump, just replace it. They're cheap and easy to do.

I don't know anything about the 1-800-Radiator company. But for $100, I can't imagine their product is that great...

 

the product is great, that is where just about everyone gets their radiators. My brother replaced the radiator in his 88 RS and we got the radiator, the factory was steel, and the one that they had was aluminum so it was a +. Thing was perfect and is holding up still after years.

 

Pull the top rad support and seperate the rad from the AC condensor enough to clean out any crap that has drawn into the space between the two. This is a problem area and should be done every year or two to help with airflow. The dual fan set-up would help also, if you don't already have it. If you do make sure the secondary fan is comeing on with the AC.

 

+1!

 

Get the aluminum one from Summit--about $250 and it is a great value, it is bigger than the stock one but is all aluminum with aluminum side tanks so you don't have to worry about the plastic tanks failing over time.

It does fit really tight against the frame rails and you may to do some trimming to the upper shroud (I had to on my 87 but I have dual electric fans).

My temp runs around 170-180 on the highway and about 190 with the fan off at a light, if it does creep around 200, I have a manual fan switch that goes on and it cools down in about 1 minute or so.

I also have a Stewart high flow water pump and 180 thermo which helps as well.

 

Does the fan run all the time? Even when you are driving?
does the temp get really hot while you are driving or just when you are stopped?
Is your ECM programmed with new fan on/off temps since you are running a 160 stat?

The fan is supposed to turn off when the car reaches 35mph, otherwise it causes a restriction in the airflow.

 

If you are running 200 and the weather is this hot, you are not going to get the operating temp down with the stock parts. For a 3rd gen, 200 is on the cool side. If you want cooler temps, the dual fan set-up is a good start. I just picked up a 4th gen dual fan shroud for $35 from Hawks and will be installing it this week or next. My `88 Iroc runs 220-240 when it`s 100 outside without the air on. I am going with a 170 thermostat and a fan switch that comes on at 185 and off at 170 for the primary fan and 190 on and 175 off for the secondary fan.

 

Running 200 with the A/C, I'd go for a 180 thermostat.

From the sounds of things, if the temps only really go up when the A/C is on and the cooling fan works, I'd check the area between the radiator and condenser as has already been mentioned. It's surprising how many leaves and bugs get up in there.