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Have "completed" resto-modifications of my 66 and depart tomorrow: Iowa to California. I have less than 300 miles on the rebuild. Runs beautifully... but loses coolant overboard (through radiator cap). Engine temp steady while running and at idle. Radiator leak free and freshly rodded. Temp gauge registers hot after driving, immediately following engine off. As simple as bad cap? It is new, 13lbs. Stant. Can you guys recommend a replacement and appropriate specs. Also any suggestions about appropriate engine break in... varied engine rpm?

A further question about placement of quarter panel drain. I have replaced both trunk floors and assume hole should be at lowest possible point on the vertical surface?

It sure would help to have an assembled Mustang to look at once in a while!

Cheers, and thanks for your help. Will post a brief account of the trip if/when I return.

Jeff
 

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Probably just a bad cap but also check the surface of the radiator neck for straighness where the cap meets the radiator neck. FYI, also probably need to get rid of cap if it has a pressure relief lever and ensure the water level in the radiator is 1/2" below the bottom of the filler neck (minimum). You also have to remember that the new replacement water pumps are of a higher flow design, somewhat not compatible with our systems and can cause the cap to raise venting coolant. This last one is a simple fix, connect an overflow/coolant recovery tank up to the radiator.

Jeff
Member: Flatheads ain't so bad association
Never trust an over 40 Chevy owner association (They have to cheat to win)
 
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yes, add a coolant overflow/recovery tank. My 68 with a 302 and a howe aluminum radiator with a 16lb cap does it too. I put on the recovery tank and it will vent some fluid into the tank especially in the summer when I am running the AC in traffic, but when the car cools the fluid just gets sucked right back into the radiator.

Jeff Crumpley
Austin, Texas
68 302 j-code coupe
99 5.0 Eddie Bauer Explorer
 

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As previously posted, I'd make sure your radiator is in good condition (if not replace), replace the cap with a 16-18 lb cap, and add an overflow system as well.

Summer is almost upon us, and I'm thinking along the same lines as you in this regard. Dickson

1965 GT fastback / "Fastbasketcase" (by Midlife)
There's a fine line between "hobby" and "mental illness" - Dave Barry
 
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Put a remanufactured water pump in. Does it have a non-original impeller design or what makes it hi-flow? Thanks for the coolant recovery idea... will do. I have a 55 Willys SW with hurricane flat six. Always thought the Ford flat V8 was the prettiest engine ever.
 
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