2017 x15 Coolant system pressure test. Not losing pressure after 20 minutes ??

[BrandonOlsen]

(12-05-2022 )tree98 Wrote:  The cap is what let's the pressure out if it gets to high. You replaced the cap with a pressure tester that's designed to hold pressure.

No the cac and radiator are not connected

The release cap was on. I pressurize it from the back of the coolant tank that goes to the radiator and blocked that hose off so pressure would be the same. I pressurized it to 14.5 - 15 psi. It stayed at 14.5-15 psi for over 20 minutes until I released the pressure from the gauge. I disconnected the air hose immediately after pressurizing it. I’ve noticed last few weeks that when the truck is sitting for a few days that when you open the coolant reservoir it has a little pressure. Release it and go check again in a few hours and has a little pressure again. Parked in a shop that’s heated it does it. Park outside it does it. Had oil sample done last week with good results. Coolant doesn’t look mixed. Fuel doesn’t look mixed. 2 days ago valve cover just started leaking on both sides and the front. 60 K miles on valve cover gasket at the time of overhaul. Everything but the head was done as it was to cummins specs .