radiator cap pressure

[Arch 93]

I've had three different pressures recommended to me for a 100-4. 4#, 7# and 9#. I've checked and only one cap can be put on the radiator, so, any recommendations as to which one I should pick?
Thanks

 

[Randy Forbes]

I use 7#; I've tried higher (to raise the boiling point of water) but you're risking the top tank bulging. It's a real Oh $hit moment when you raise the hood after a drive!

 

[Keoke]

For as long as I can remember 7 LBsis standard

 

[Bob_Spidell]

I believe 4lb is standard for the 100s (working from memory so could be wrong). The 100 rads are different than the 6-cyl rads, so may not take any extra pressure.

 

[TimK]

if your cooling system is in good shape, you shouldn't need more than 4 lbs. more pressure risks bursting things. if you overheat, find the cause and fix it. make sure the cap is long enough to seal, or it wont make any diff how much pressure it has. i needed a cap for a truck to seal.

 

[Arch 93]

Thanks for your help. Since I'm not having any overheating problems at the moment,I'll go with the 4# and see how it goes.
Thanks again.