Rad cap - 7# or 13#?

[J60FI]

I had a bad rad cap, best I can figure... it would leak under slighter pressure.. I took the rad out had it pressure tested .. The guy at the shop suggested going to a 13# cap,, so i did.. NO LEAKS..

The rad is a copper harrison rad ... should i keep the 13 # or buy the rated 7 # cap.. At least one that fits properly?

What is the harm in keeping the 13#?



THanks..

 

[JohnZ]

The rad is a copper harrison rad ... should i keep the 13 # or buy the rated 7 # cap.. At least one that fits properly?

What is the harm in keeping the 13#?



THanks..

No harm at all - the only difference between the two of them is that the 13# cap will give 13* more margin than the 7# cap to boilover temperature ("puking" through the overflow hose) due to the increased pressure in the system; neither cap will affect normal operating temperature - that's determined only by the heat rejection capability of the radiator and the airflow through it.

 

[J60FI]

No harm at all - the only difference between the two of them is that the 13# cap will give 13* more margin than the 7# cap to boilover temperature ("puking" through the overflow hose) due to the increased pressure in the system; neither cap will affect normal operating temperature - that's determined only by the heat rejection capability of the radiator and the airflow through it.

Thanks John....

 

[Tom Bryant]

I have always been told by the shops I have used to run a lower pressure cap on old radiators. You never know how weak the seams are becoming even if it doesn't leak. I have never had any problem running 7# caps on old cars but I never run over a 180 thermostat either.

Tom

 

[2X4's 60]

I have always run the lower pressure caps without any problems. Like Tom said, it reduces your chances for leaks. The front motor mount design on C1's doesn't need any help to start leaking.

Jim

 

[Tom Bryant]

Amen to that. I have to rebuild my water pump so I get to take my mount off again. It needs painted anyway.

 

[c5vetter]

Hey Tom,

youse going to be at the St Charles NCRS National during 21-24 July? Will be driving the Lady in on the Road Tour from Maryland - get in on Sunday, July 20

 

[Tom Bryant]

No. I'm not going to make it. I have to get the truck running this summer and then I have to consentrate on the '59 if I want to drive it at all next year on it's 50th anniversary. My next vacation away from home will be in January. I'm heading out to Phoenix to stay with my oldest son and his family and take in B-J.