MP7 building pressure in cooling system in Engine and Transmission Posted Saturday at 11:49 PM 10 hours ago, fjh said: Easier stuff first rad cap , egr cooler ! Is it throwing up any codes? No codes. What I do with these is put a pressure tester on the coolant tank, fire it up and watch to see if the pressure builds. This one instantly started climbing, normally I don't see much pressure building until the coolant temp starts to come up. At an idle the pressure steadily climbed to 10 psi in about 3 minutes. If I ran the rpms up it would build pressure even faster. I've only seen this on an mp7 one other time which ended up being pitting in the head where the injector cup seats, letting compression into the cooling system. As far as the egr cooler, am I correct that there wouldn't even be 10 psi of pressure there at an idle? I know that it isn't leaking coolant anyway.