Gaps around radiator
Thread Starter
3rd Gear
Joined: May 2016
Posts: 3
Likes: 0
Gaps around radiator
My 76 has been overheating on the highway, 3 speed auto and anytime its above 3000 rpm the temperature steadily climbs to 250+. In traffic or just cruising around its completely fine and hovers around 200. i replaced the stock rad and fan with a flex-a-lite aluminum rad and electric fan combo.(issues came after this replacement) I know there could be a multitude of issues but the easiest one i can think of is closing the gaps between the rad and the frame to ensure the air coming in at high speed is going through the rad and not around it.
Long story short, im looking for some sort of high heat foam / rubber weatherstripping and adhesive to close these gaps off. any help would be greatly appreciated!
Long story short, im looking for some sort of high heat foam / rubber weatherstripping and adhesive to close these gaps off. any help would be greatly appreciated!
Drifting
Joined: Jul 2011
Posts: 1,697
Likes: 139
From: Syracuse NY
My 76 has been overheating on the highway, 3 speed auto and anytime its above 3000 rpm the temperature steadily climbs to 250+. In traffic or just cruising around its completely fine and hovers around 200. i replaced the stock rad and fan with a flex-a-lite aluminum rad and electric fan combo.(issues came after this replacement) I know there could be a multitude of issues but the easiest one i can think of is closing the gaps between the rad and the frame to ensure the air coming in at high speed is going through the rad and not around it.
Long story short, im looking for some sort of high heat foam / rubber weatherstripping and adhesive to close these gaps off. any help would be greatly appreciated!
Long story short, im looking for some sort of high heat foam / rubber weatherstripping and adhesive to close these gaps off. any help would be greatly appreciated!
Team Owner
Joined: Sep 2006
Posts: 31,202
Likes: 4,287
From: Westminster Maryland
Hi ns,
Originally there were pre-cut dense foam strips on all 4 sides of the radiator that sealed the radiator to the core support.
These were vital in assuring that the cooler air was being pulled THROUGH the radiator rather than AROUND it.
Will the kit for a 76 work with your present set-up?
If so they're readily available.
Regards,
Alan
Originally there were pre-cut dense foam strips on all 4 sides of the radiator that sealed the radiator to the core support.
These were vital in assuring that the cooler air was being pulled THROUGH the radiator rather than AROUND it.
Will the kit for a 76 work with your present set-up?
If so they're readily available.
Regards,
Alan
Team Owner
Joined: Sep 2006
Posts: 31,202
Likes: 4,287
From: Westminster Maryland
Hi ns,
Originally there were pre-cut dense foam strips on all 4 sides of the radiator that sealed the radiator to the core support. They were different sizes depending on the gap they were intended to seal.
These were vital in assuring that the cooler air was being pulled THROUGH the radiator rather than AROUND it.
Will the kit for a 76 work with your present set-up?
If so they're readily available.
Regards,
Alan
Originally there were pre-cut dense foam strips on all 4 sides of the radiator that sealed the radiator to the core support. They were different sizes depending on the gap they were intended to seal.
These were vital in assuring that the cooler air was being pulled THROUGH the radiator rather than AROUND it.
Will the kit for a 76 work with your present set-up?
If so they're readily available.
Regards,
Alan
Le Mans Master
Joined: Aug 2006
Posts: 7,419
Likes: 1,555
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
You should have an air dam (something like #6).
It helps to push the air up and into the radiator.
It helps to push the air up and into the radiator.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
The correct hose has an internal spring to prevent just that.Always check the replacement hoses for that. I have found "correct" hoses from Delco that did not.
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Race Director
Joined: Mar 2003
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From: Eustis ( Area 51 Bat Cave ) Fl
So when its overheating at highway speeds is the fan off, if yes, can you do a test, run at highway speeds with fan on, see if it keeps cool, if yes, then the foam might just help, if no then the foam likely wont fix it, because its not an air flow issue but ahem, a radiator or other issue.
Thread Starter
3rd Gear
Joined: May 2016
Posts: 3
Likes: 0
Right on fish...
So when its overheating at highway speeds is the fan off, if yes, can you do a test, run at highway speeds with fan on, see if it keeps cool, if yes, then the foam might just help, if no then the foam likely wont fix it, because its not an air flow issue but ahem, a radiator or other issue.
So when its overheating at highway speeds is the fan off, if yes, can you do a test, run at highway speeds with fan on, see if it keeps cool, if yes, then the foam might just help, if no then the foam likely wont fix it, because its not an air flow issue but ahem, a radiator or other issue.
Sadly i have had this conundrum for almost 3 years. i have tried a new water pump, installing the air dam as mentioned, timing seems to be correct, lower hose both has the spring and is rather new. Ill look into the foam mentioned above and see if that fixes it on a warmer day in Canada, might take a while to get there mind you. (ive noticed if its below 18 Celsius then the issue almost goes away completely)
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
I would have thought it was the lack of an air dam also, that was the problem with mine when I first got it.
So take another look at the electric fan. Is it wired properly, not running in reverse polarity? Running in reverse would be able to move air through the radiator backwards at low road speeds, but just block flow at highway speeds.
FWIW, I don't have any of the foam around my radiator at all and it cools a 375 horse motor just fine. (DeWitts with dual electric fans.)
So take another look at the electric fan. Is it wired properly, not running in reverse polarity? Running in reverse would be able to move air through the radiator backwards at low road speeds, but just block flow at highway speeds.
FWIW, I don't have any of the foam around my radiator at all and it cools a 375 horse motor just fine. (DeWitts with dual electric fans.)
Melting Slicks
Joined: Sep 2005
Posts: 2,700
Likes: 895
From: Warminster PA
Check that the vacuum canister will hold a vacuum. I chased an overheating problem for a while in one of my cars. Found out that the vacuum diaphragm had a slow leak and at steady highway cruise rpm it would bleed down leaning things out.
Beg, borrow or steal a vacuum pump and test it that way.
Tom
Race Director
Joined: Oct 2008
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From: Long Island
I agree with Allen - if the foam is missing the air will go around the radiator due to higher pressure in the engine compartment. My 71 ran hot without the foam. Now it runs cool with the foam seals. Radiator to Radiator support.
Former Vendor
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From: Brighton
Drifting
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From: NSW, Australia
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