I think too that 21 psi is quite high pressure that puts stress on a lot of parts in the cooling system. And yes when plastic becomes brittle, added pressure might blow a hole in the tank. I don`t know why modern cars have so high coolant pressure. I believe my volvo have up to 14 psi pressure
cap on the expansion tank. When i went to mechanic school we were taught that 14 psi is max pressure when pressure testing the cooling system, above that could cause damage.
cap on the expansion tank. When i went to mechanic school we were taught that 14 psi is max pressure when pressure testing the cooling system, above that could cause damage.