C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Overheating problem

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Old Jul 20, 2024 | 03:05 AM
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Default Overheating problem

Hello, I am having a problem with overheating. On my 1986 (l98). Yes car is actually getting hot. I cleared the radiator, water pump pumps and isn’t leaking. have a new thermostat, coolant, radiator cap, and cooling fan. Test for combustion gas in coolant came back negative, system vacuum filled and bled multiple times. Fan is always on and still overheats. Used to run around 175 now climbs all the way to mid 230s before I pull over to cool it down. Oil gets to 250-270. It seems like the oil is heating up first and driving the temperature of everything else up as well. Has anyone else had a similar problem? Where should I look next?
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Old Jul 20, 2024 | 03:06 AM
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I don’t want to just slap a bigger radiator in there and call it a day. The system has and should work with the stock components.
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Old Jul 20, 2024 | 06:08 AM
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Is the original catalytic converter still on the car? I would take some temperature readings of the exhaust pre-cat, cat, and post-cat. If it's severely plugged, this can drive up oil temps. Just a thought, good luck👍
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Old Jul 20, 2024 | 08:34 AM
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Originally Posted by moodydavid16
Hello, I am having a problem with overheating. On my 1986 (l98). Yes car is actually getting hot. I cleared the radiator, water pump pumps and isn’t leaking. have a new thermostat, coolant, radiator cap, and cooling fan. Test for combustion gas in coolant came back negative, system vacuum filled and bled multiple times. Fan is always on and still overheats. Used to run around 175 now climbs all the way to mid 230s before I pull over to cool it down. Oil gets to 250-270. It seems like the oil is heating up first and driving the temperature of everything else up as well. Has anyone else had a similar problem? Where should I look next?
How did you clean the radiator? If you didn't take it out, it could look like this

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Old Jul 20, 2024 | 12:50 PM
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Originally Posted by Cruisinfanatic
How did you clean the radiator? If you didn't take it out, it could look like this

Yes I took the radiator completely out and sprayed water through the fins till clear
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Old Jul 20, 2024 | 12:51 PM
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Originally Posted by '78CorvetteS.A.
Is the original catalytic converter still on the car? I would take some temperature readings of the exhaust pre-cat, cat, and post-cat. If it's severely plugged, this can drive up oil temps. Just a thought, good luck👍
Yeah it does still have the stock cats. What temps should I be looking at if they aren’t clogged?
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Old Jul 20, 2024 | 04:11 PM
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Originally Posted by '78CorvetteS.A.
Is the original catalytic converter still on the car? I would take some temperature readings of the exhaust pre-cat, cat, and post-cat. If it's severely plugged, this can drive up oil temps. Just a thought, good luck👍
also I do have the air pump deleted, could this be causing an issue?
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