Yes, the radiator or pressure cap should keep the system from over-pressurizing. I made mention of a faulty cap earlier. I think that it’s foolish to replace a radiator without a new cap also…
If the pressure gradually increased over time and the maximum over-pressure wasn’t too great , yes, I’d guess the radiator cap would be able to open and relieve the force as needed. But if there were internal pressure spikes from hot combustion gasses finding their way to the cooling system, quick pressure rises w/time, or the maximum overpressure was just overwhelming, the radiator cap might not be able to relieve the force quickly enough. My VW Rabbit developed what I thought was a head gasket problem late in life and the symptom was a cracked radiator, and replacing the radiator & cap did no good, cracked the new radiator too.
2 Likes
Could be a defective water pump.
1 Like