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Radiator cap rating
https://www.slantsix.org/forum/viewtopic.php?t=41832
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Author:  Herr Otto [ Thu Sep 09, 2010 5:53 pm ]
Post subject:  Radiator cap rating

I just had my radiator recored and would like to know what is the correct pressure cap I should be using? The one I took off was a 7lb.
Thank you

Author:  Aggressive Ted [ Thu Sep 09, 2010 7:09 pm ]
Post subject: 

The manual for my 74 states 16 lbs. Older cars maybe different.

Author:  wjajr [ Fri Sep 10, 2010 5:31 am ]
Post subject: 

!967 calls for 16 psi cap as well.

What one has to be aware of when changing from a 7 psi back to a 16 psi cap, you may experience a failure of one of the hoses, heater core, or water pump packing.

These items have not been under the higher pressure for some time, may have degraded for whatever reason, and will fail at the higher pressure. They would have failed with a 16 psi cap had someone kept using one as well, but perhaps sooner.


What I’m saying is, if your system is in good working order, no problem. If it is not, there will be a leak, it may happen right off, or a month later, so keep a look-out for drips, and windshield fogging from a bad heater core.

Author:  Doc [ Fri Sep 10, 2010 11:52 am ]
Post subject: 

Personal experence has me running lower pressure on all my "round top tank" radiators, I use the 7 lb caps on those.
I find that the higher pressure cap will split the tank to core solder joint, given some time.
The "square top tank" radiators don't seem to have this problem so I run the higher pressure cap on those.
DD

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