1990 overheating
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Cruising
Joined: Jul 2019
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1990 overheating
Hello! I know there a lot of threads covering this topic already I'm just a little confused , this is my first corvette. But I'm having over heating issues at idle according to my digital Guage the car is running around 245 and climbing. When driving will jump from 200 to 230. Replaced cap and thermostats tried burping the system a couple of times no luck. No coolant in oil so I don't think I have blown head gasket. What do you guys think any help will be appreciated. Fans do kick on
Last edited by Split29; Aug 27, 2021 at 05:23 PM.
Drifting
Joined: Jan 2021
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From: Northern California
Your radiator is probably clogged with leaves and debris in between the A/C condenser and the radiator itself. Happens all the time because of the design with the lower body air intake to the radiator area, and the fact that there is no screen to prevent leaves and road debris from entering that area. Remove the radiator top plastic housing cover, then remove all the junk. I think it helps to actually lift the radiator out and wash the fins / blow compressed air through them to clean, but in most cases you can still do this with the radiator in the car.
There are a ton of articles in this forum regarding this problem. Most all of us either have it and don't know, or have had it and fixed it.
There are a ton of articles in this forum regarding this problem. Most all of us either have it and don't know, or have had it and fixed it.
Drifting
Joined: Jan 2021
Posts: 1,311
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From: Northern California
Racer
Joined: Feb 2019
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From: Jackson, mi
how did you "burp" it? you almost have to get the car rocking back and fourth side to side and work the air pockets out, it can be a real pain. i had to do this with my car when i bought it. guy said it was over heating and he couldn't get it fixed. i filled the top reservoir full. bottom reservoir full and got that thing rocking side to side good several times while running. i finally worked the air out and i never had an over heat problem myself while driving it
Team Owner
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X2 on removing the radiator. You will be surprised how much junk and road grime are in there. It is definitely worth removing it completely and hosing it down.
Melting Slicks
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My '90 idles and runs at about the same temperature. It's been in the low to high 90s most of the summer here, too.
Haven't had any problems.
To me that's not really overheating.
Haven't had any problems.
To me that's not really overheating.
Team Owner
Joined: Aug 2004
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From: Park City Utah
He needs to fix it so that it works right. You might need to, too.
Team Owner
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While it's not technically in the "red", the cooling system is not controlling the engine temps, and it's not acceptable. The cooling system should be able to drive the coolant temps down against the t-stat. Let me re-state that; the cooling system should have more than enough cooling capacity to keep the temps down against the stat.....in nearly all conditions that we see. If you're towing a 25' boat up the Davis Dam incline in August...then maybe we see 245* temps. Otherwise? Absolutely not. The cooling fans should drive the coolant temps down to their turn off point, and not allow it much (1 or 2 degree) above it's turn on point. This guy is getting 245* at ilde??? No. No way, that is not right, and even though it's not technically overheating, it's not right b/c if he's already at 230 hwy and 245 idle....he has no margin left! If he puts his car in a more severe operation condition than idling or "driving", he's got no where to go, but straight into the RED....overheat.
He needs to fix it so that it works right. You might need to, too.
He needs to fix it so that it works right. You might need to, too.
Last edited by SmokinBlack; Aug 28, 2021 at 08:47 AM.
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Team Owner
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If you end up pulling your radiator, a little Simple Green or similar and a garden hose will pretty much take care of anything that is in the fins.
Racer
Joined: Jun 2019
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From: Franklin, TN
Can someone explain how to handle the A/C connections? I assume you can't completely remove the radiator without disconnecting them. And, I guess that will de-pressurize the system and cause a loss of refrigerant.
Team Owner
Joined: Aug 2004
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From: Park City Utah
You could reprogram your fans or install an manual switch to drive temps down at low speeds/stop and go/idle.
Still, I agree with cleaning the radiator as a good PM measure and flushing coolant annually; I don't like hot running cars and I don't like replacing heater cores.
Burning Brakes
Joined: Sep 2017
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Hello! I know there a lot of threads covering this topic already I'm just a little confused , this is my first corvette. But I'm having over heating issues at idle according to my digital Guage the car is running around 245 and climbing. When driving will jump from 200 to 230. Replaced cap and thermostats tried burping the system a couple of times no luck. No coolant in oil so I don't think I have blown head gasket. What do you guys think any help will be appreciated. Fans do kick on
Melting Slicks
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Temperature was only in the 80s today.
Melting Slicks
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While it's not technically in the "red", the cooling system is not controlling the engine temps, and it's not acceptable. The cooling system should be able to drive the coolant temps down against the t-stat. Let me re-state that; the cooling system should have more than enough cooling capacity to keep the temps down against the stat.....in nearly all conditions that we see. If you're towing a 25' boat up the Davis Dam incline in August...then maybe we see 245* temps. Otherwise? Absolutely not. The cooling fans should drive the coolant temps down to their turn off point, and not allow it much (1 or 2 degree) above it's turn on point. This guy is getting 245* at ilde??? No. No way, that is not right, and even though it's not technically overheating, it's not right b/c if he's already at 230 hwy and 245 idle....he has no margin left! If he puts his car in a more severe operation condition than idling or "driving", he's got no where to go, but straight into the RED....overheat.
He needs to fix it so that it works right. You might need to, too.
He needs to fix it so that it works right. You might need to, too.
To me, that matters greatly.
But whatever. It certainly can't hurt to inspect the cooling system.
My entire cooling system is pretty much new and completely full, though.
When I went out today for a ride, my '90 also stayed in the 185-200 degree range when moving.
But it was only 80 degrees outside, compared to the much higher outdoor summer temperatures when the system ran hotter.
I think he's overthinking it, but there's nothing wrong with cleaning an old sysem up. Certainly can't hurt.
Last edited by Natty C; Aug 29, 2021 at 04:37 AM.
Melting Slicks
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A lot of times you'll read somewhere that the coolant capacity is 14.6 quarts. That's wrong.
Last edited by Natty C; Aug 29, 2021 at 03:45 AM.
Team Owner
Joined: Aug 2004
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From: Park City Utah
.....but I do. No C4 should be hitting 245 while idling....even at 100*F temps. And no C4 should be hitting 230, while cruising on the highway.....even in 100* temps. The cooling system should have the capacity to prevent either of those numbers from happening in those conditions -the conditions that the OP shared with us. If he is really seeing 245 at idle....even on a 100* day....something has gone awry.
Burning Brakes
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