C32 FW cooler

I'm not an engineer, but DK that there's a difference. The rated pressure is generally on the radiator cap. Bring it up to that pressure and it holds or it doesn't. I believe for that motor it should be 13 PSI according to the CAT parts manual.

Lolololol, there’s one pressure and it’s on the radiator cap.

SHOULD be unless someone changed the cap along the way. Good for the OP to check cause too much pressure wouldn't be good.

Pressure caps can fail, or as NYCAP notes; incorrectly supplied. There's also a limit to how much pressure can escape via the overflow tube port in a given amount of time. There should be a safety margin on any spec. I would hope for 3x on critical equipment, but a quick Google on the subject comes back with:

The hydrostatic test pressure at any point in the piping system shall not be less than 1.5 times the design pressure, but shall not exceed the maximum allowable test pressure of any non-isolated component, nor shall it exceed the limits of calculated stresses due to occasional loads.

That may be for an industry specific system, but industry standards spread across to other disciplines. I would think that if the cooler is tested at 1.5x and the gaskets failed, it would be good results, rather than failure in service.

I'd be real hesitant to apply 3x or even 1.5x the recommended pressure, especially with older gaskets.