Radiator cap
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Cargo Master
Joined: Jul 2015
Posts: 2,069
Likes: 138
From: tucson
Radiator cap
My '64 F-250 has a 390 installed by a PO. I need to replace the rad cap. The existing one is rated at 7lbs and has the locking lever on top. The one the parts store sold me is rated at 13lbs and has a solid top. The truck has ac it but it is not working at this time. I think the engine is early '70s vintage. What cap do I need?
Thanks.
john
Thanks.
john
Lead Gopher
Joined: Aug 2012
Posts: 10,066
Likes: 1,620
From: Seattle
Original radiator cap on these trucks did not have the locking lever on top. And all that I have seen that were original were 13 lbs. The rivet in the center has the hole into it a ways, too.
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Lead Gopher
Joined: Aug 2012
Posts: 10,066
Likes: 1,620
From: Seattle
If you can run 7 and not lose any fluid around the cap then that's golden. I wasn't trying to imply that 13 was the only way to go, just that it was what I've seen on the stock ones. The MPC shows 13, too, but 7 seems to be the other common one for things like tilt-cab models and diesels.
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Laughing Gas
Joined: Sep 2003
Posts: 968
Likes: 5
From: Corbett, Oregon
I have encountered some problems "blowing" the top tank seams on radiator using caps in the 12#-15# range. These have been only on trucks with large top tanks and older radiators, such as a late 70's F series Camper Special or a factory 460.
I have never encountered such problems on a radiator with a smaller tank, such as a Mustang or Falcon.
As long as your radiator is in decent shape I would use what Ford recommended. If in doubt as to the condition of the radiator, drop the cap to the 7#. You will lower the coolant boiling point about 15* compared with the 13# cap, but lower the risk of having a tank seam let go.
Hope this helps.
I have never encountered such problems on a radiator with a smaller tank, such as a Mustang or Falcon.
As long as your radiator is in decent shape I would use what Ford recommended. If in doubt as to the condition of the radiator, drop the cap to the 7#. You will lower the coolant boiling point about 15* compared with the 13# cap, but lower the risk of having a tank seam let go.
Hope this helps.
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Cargo Master
Joined: Jul 2015
Posts: 2,069
Likes: 138
From: tucson
I just had the radiator repaired where it had split the seam where the top of the tank is soldered on. Since it is an older rad with a large tank, I think I will go back for a 7 pounder.
Thanks.
john
Thanks.
john
Posting Guru
Joined: Jan 2011
Posts: 1,670
Likes: 8
The only time a radiator is going to blow a seem, is if, one or all of these problems exist:
-radiator core is plugged up
-radiator cap not functing correctly
-water is low and steam builds up.
None of these problems should exist if proper maintenance is followed.
Use a 13lb. Cap and installed an overflow canister/bottle. Make sure your radiator is not plugged up with crud. And with that said, never ever use anything except distilled water.
-radiator core is plugged up
-radiator cap not functing correctly
-water is low and steam builds up.
None of these problems should exist if proper maintenance is followed.
Use a 13lb. Cap and installed an overflow canister/bottle. Make sure your radiator is not plugged up with crud. And with that said, never ever use anything except distilled water.
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