Radiator caps

Blu Dice

Blu Dice

Senior Member
I read on here once - I think - an old flathead boy said never screw down the radiator cap down tight - run it with the cap loose - and have the fluid level up to the coils only.
Thoughts.
 
The radiator should be filled up to the filler neck, 22 quarts and the cap should be tight. If you loose water you have a problem that needs to be fixed. The radiators all have over flow tubes. G.M
 
The radiator usually will find its' own level. Well mine does anyway & that is down from the top & above the tubes. I run Skips pumps & check valve on my 36LB engine.
 
At least on the 39 - 40 radiators, you will gain the best results from filling just past the upper core (plate). Authentic caps have zero pressure so nothing is gained by leaving it loose.
 
Been running my 8BA with no pressure since 1950 and never overheated once. I remove the lower seal on the cap and use an overflow tank, so my rad is always full to the top. I do have to add coolant occasionally. Not very often.
 
4t8v8 said:
Been running my 8BA with no pressure since 1950 and never overheated once. I remove the lower seal on the cap and use an overflow tank, so my rad is always full to the top. I do have to add coolant occasionally. Not very often.
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I've never heard this before - does any coolant ever go into the overflow tank?
Mine is a EAB ('52 Customline) - got it last Nov and I think it's still trying to find its comfort level. Since I don't drive it very far I've wondered if it would be best to not run a pressured system. I'm installing a overflow tank right now as a precaution.
 
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On the subject of radiator caps, my new walker radiator ( for 32 Ford with flathead) came with a 7 lb cap, is this too much? I've always been told it should be 4 lb.
 
Blu Dice said:
I've never heard this before - does any coolant ever go into the overflow tank?
Mine is a EAB ('52 Customline) - got it last Nov and I think it's still trying to find its comfort level. Since I don't drive it very far I've wondered if it would be best to not run a pressured system. I'm installing a overflow tank right now as a precaution.
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Yes it does, Blu. I used an overflow tank from a brand X S10 and the coolant transfers back and forth great. I like it because the rad is always full. Using 16o thermos it runs between 160 and 180 year around. Hope it works for you.
 
4t8v8 said:
Yes it does, Blu. I used an overflow tank from a brand X S10 and the coolant transfers back and forth great. I like it because the rad is always full. Using 16o thermos it runs between 160 and 180 year around. Hope it works for you.
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For what reason did you decided to do this - this is in a '48 Ford right?
 
I installed a small, inexpensive coolant recovery tank (purchased from O’Reilly’s) inside the engine bay. I ran a long hose from the radiator overflow to the tank. The overflow will collect in the tank and, when the engine cools, it is sucked back into the radiator. The radiator cap seals well and keeps the system “closed” which allows me to keep the radiator full. If needed, I add coolant to the overflow tank. I have this setup for about 12 years on ’36.
Kerry
 

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Your car came from factory with a 4lb. pressure cap. I would put it back to factory specs. and let water find it's own level. If it doesn't overheat drive it and enjoy.
 
I am not set up for pictures. Sorry. I mounted the tank to the front of the left inner fender, cut the overflow tube shorter and ran a hose from it to the tank. Pretty simple, really. Works just as 6lucky13 described. Been on there for about 10 years. Found the S10 tank on EPAY.
 
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