So i want to add a radiator overfill tank to a vehicle that doesn't have one. I know I need some hose and a catch tank for the coolant that comes out, but do I need to change the radiator cap? For some reason I have it in my head that the radiator caps are different for systems that have an overflow tank and those that don't. Am I nuts?

You may or may not be nuts; your wondering about radiator cap construction is insufficient to establish either case as fact.

You're correct, rad caps for recovery systems have an upper seal not present on caps for open-vent systems. A cap for a recovery system has two rubber seals: One on the face of the main valve, which seals against the lower flange ring of the radiator neck, and another larger one just under the cap's underside, which seals against the upper flange ring of the radiator neck. The upper ring's seal against the upper flange means that when the system cools down and coolant volume in the radiator decreases, the resultant suction is channeled via the open centre valve through the overflow tube, which draws coolant from the reserve tank back into the radiator.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

The radiator caps are different.

But the new overflow kind can be used in place of the older style.


So if you already are using the new style, you don't need to replace the cap.


Generally, the new style has a 2 gaskets. One for pressurization, the other to seal the neck.

The old style only has a gasket for the pressurization, and usually sheet metal for the neck (won't seal the neck)

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Thanks guys! That's what I thought. Right now I have a single seal cap.

Jury is still out on whether or not I am nuts.

Hey Reed You have ME convinced

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered