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I have a 89 IROC. New GM engine 350 HO version, New everything on the engine, New Radiator, New hoses, new thermostat swapped 3 times. . Both my fans are new 12 inch electric fans. One comes on at 165 and the other is controlled by the computer. The air dam is in place.
My temp are hitting 230 and 240. I even checked it with my PC connected and the temp matched my digital temp gauge. I have read through a lot of the cooling threads this just makes no sense.
Im tired of messing with it geez. What does it take to cool these cars??
What Teal and Karr are getting at with the fan questions is that they want to make sure that you don't have 2 pusher fans acting like puller fans as that doesn't work! As for the air dam, they just want to make sure that it isn't cracked or not fully in place. I know you said that you have a new radiator, but when you replaced that did you check the fins for the AC condensor and make sure that they aren't clogged with road dirt and all of the dirt that was caked between it and the old radiator was fully removed?? If there's crap in the condensor fins then air isn't even getting to the radiator to help cool it. I have seen that a lot of times.
Also, how about the often overlooked less likely things...belt routed correctly, exhaust free flowing, timing set etc..
These cars have basic cooling systems so I like to rule out the possible random oddball issue that more than likely won't but MAY cause the issue!
I had a similar issue once...the car couldn't;t get rid of an air bubble for the longest time for some reason. Of course I didn;t figure it out til leventually it burped and all was fine.....almost 3 days later lol
The engine I removed was also running to hot. I changed it all. The only thing left was the heater core which is new and the bypass valve. The ECM reading shows it really is that hot. This is the new radiator..
Do keep in mind that just because the fans are moving, doesn't mean they're moving fast enough...I've seen several times where the fan motor was tired, and simply moving too slow--but since it was moving, someone eliminated it as a possible issue.
The bypass valve could be clogged or starting to clog but it's not likely to do too much to be honest as the coolant should still flow through it and even if it's stuck open or closed, the coolant would still flow unless the it's clogged. If you take the radiator cap off, does the coolant move pretty well? Do you have any way to measure the different spots for different temperatures like an infrared temperature gun. Just wondering if maybe a cylinder is running too rich or too lean or there is a clog in the cooling system or anything like that??
I would also do a pressure test. Maybe you have a small air leak in changing all this stuff and it is not pressurizing the system properly.
Vinny R is correct - if the system is not developing the correct pressure, this will have an impact on your running temperature.
What pressure radiator cap are you using? Have you performed a system pressure leak down check?
As a process in the troubleshooting my recommendation would be to pressurize the system and do a leak down check.
Additionally, you may want to insure you have all the air bled from the system. As a few others here have made reference to,
air in the system can cause problems.
I personally think that fans that are directly on the rad and are not an X- amount of distance away don't do well since they only pull air where they touch the rad and don't have a shroud.
1. Does it get hot instantly when you idle? Stock the fans probably don't come on for I think 10 - 20 minutes at least, so if it gets hot too fast, its possibly not fan related...but if it overheats after the stock fans WOULD come on stock, maybe its fan related as they can't cool enough.
2. Does the ac get cold if you have ac? If not that might indicate air flow / fan issue.
3. Did you make sure it is the correct water pump for serpentine system? I once got the wrong part that otherwise looks stock and took me forever to realize the wrong part was in the box...because its identical to another part.
4. Would you consider wiring in LS / LT fans? You seem to have good skills so I imagine this wouldn't;t be a problem for you.
I replied to your post on facebook but I'll post on here to.
Whats it idling at ? I had a bad tps which was causing a high idle and not allowing it to idle down enough while driving it caused it to run at like 220 or a little pass with my fan running
I want to thank everyone its finally cool again. I know this was mentioned. My 83 had a brand new air damn I installed from Hawks motorsport. I thought the IROC was cooled from the holes in the front at the fog lights and that the air damn was the radius plastic piece under the car running from the front bumper. After I reset the timing and put in a new 160 thermostat and set the fans to come on at 180 is did some better but finally went back up to 248. I verified everything again from flow direction to you name it. So I looked again online and saw the air damn was for 82-92 so I made a temp metal one and put it on and damn it went down to 205. I replaced everything under the hood over a damn piece of plastic. So once I get the new one I bet it runs even cooler since mine is shorter than the radiator.
I want to thank everyone its finally cool again. I know this was mentioned. My 83 had a brand new air damn I installed from Hawks motorsport. I thought the IROC was cooled from the holes in the front at the fog lights and that the air damn was the radius plastic piece under the car running from the front bumper. After I reset the timing and put in a new 160 thermostat and set the fans to come on at 180 is did some better but finally went back up to 248. I verified everything again from flow direction to you name it. So I looked again online and saw the air damn was for 82-92 so I made a temp metal one and put it on and damn it went down to 205. I replaced everything under the hood over a damn piece of plastic. So once I get the new one I bet it runs even cooler since mine is shorter than the radiator.
It's amazing how a piece of flat plastic can affect these cars so much!
Be glad that you found it and that things are working again. Look at it this way also, all of the parts that you replaced were mainly maintenance items and will help the car to continue to run well and cooler in the future.
It's amazing how a piece of flat plastic can affect these cars so much!
thats the only way for air to be drawn into your radiator area is from under neath . the fog lights area isnt big enough for cooling alone. glad you found your problem
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