My friend has a "60" F100 radiator in his truck. He just purchased a new cap and noticed that it was a 13lbs. cap. The cap he had on it was a 7 lbs cap. Will it hurt to run a 6 lbs more cap on it? I couldn't answer his question....

 

Thats more than double the pressure, he could end up with water coing out in all sorts of places, radiator, heater, speedometer. Get one closer to the seven pounds.

 

You didn't mention what engine he has. Some engines require 13psi caps. The higher psi cap will increase the boiling point of the coolant in the system.

 

The other restriction on using pressure caps is the radiators ability to handle the pressure, for instance all the radiators from mid-fifty are supposed to use 7 lb caps(per notes in their catalog.

 

53- It's a Ford 302,
B/B- That was my question???? I heard the older radiators came apart if a higher temp cap was used. If I recall, that applied only to the original older radiators? I know the one he has has a new core, but the upper and lower tanks are still original. I have a 7 lbs on my truck, but I noticed I have a 13lb cap on my 66 Mustang and both engines are a 289? Never had any problems with either one.

 

Ed, according to mid- fifty catalog it applies to their 4 row highest efficiency radiators as well as their stock style aluminum radiators. after reading that, I switched from a 14lb. back to a 7lb. I didn,t want to take any chances on the radiator or on the heater core and hoses on my vintage air. last thing I want is leaking anti freeze on my new carpet. 150 mi. so far this way and everything seem fine.

 

I'd try the 7 lb cap and if it doesn't boil over continue to use it. The higher pressure cap will increase the boiling point and help keep the coolant in the radiator. Actually, if your friend is running a new core a 13 lb cap should be fine. Most modern radiator cores are tested up to 18-20 lbs...

Vern

 

those early round tanks are a bad design and weak to begin with and are prone to cracks at the seams, I wouldn't push it over the 7lbs..thats what they were designed for