Hello all,
I put a new radiator in my 2006 Durango with Jasper hemi a couple yrs ago. It started leaking at a tank seam the other day so I brought it to a guy that's been rebuilding radiators for nearly 40 yrs. I asked him about the high 20 lb radiator cap that this thing calls for. He says he only sees caps in the low 20's on drag cars. He says he puts 16-18 lb caps on all Jeeps and Dodges with hemi's. I asked him why it would call for a 20 lb cap. He sarcastically said because Chrysler wants you to buy intake manifolds and gaskets because they're plastic.

My question is this: I've read that these things have intake manifold gasket issues which lead to water getting into the engine from bad cowls. Could it be that this 20 lb pressure cap is a contributing factor in intake manifold gaskets going bad and my plastic radiator breaking at the seam?

I put an 18 lb cap on when I got the radiator back..

 

Raising the system pressure also increases the temp required for the coolant to boil. Of course, if you have a proper mix of water/coolant, and the correct thermostat, that really shouldn't be an issue. Most radiator caps I see are 16lbs.......