OK. new to BMW. Fine car. But it seems like cooling system issues are common.
I understand that plastic fails with age, and that is a likely cause of system failures.
But I can't help wondering if the design is also part of the problem.
Many (most???) cars use an overflow tank and a pressure relieve valve in the radiator cap. If the pressure gets too high, the excess fluid is directed to the overflow tank. When things cool down fluid is sucked back in from the tank.
It seems BMW uses a closed system with an "expansion" tank. I guess the idea is that the radiator will always stay filled with liquid - as it expands it compresses air in the expansion tank to make room. If somebody overfills the system there is not enough room, and something explodes. Exploding seems common here. I wonder if perhaps this is due to not leaving enough air in the expansion tank. Or maybe it is user error - if you fill above max you will likely have an explosion since the expanding fluid has no place to go.
So, anybody know why they designed it this way? Is there any over pressure release valve at all in the BMW system? If not, seems like a recipe for disaster.
I understand that plastic fails with age, and that is a likely cause of system failures.
But I can't help wondering if the design is also part of the problem.
Many (most???) cars use an overflow tank and a pressure relieve valve in the radiator cap. If the pressure gets too high, the excess fluid is directed to the overflow tank. When things cool down fluid is sucked back in from the tank.
It seems BMW uses a closed system with an "expansion" tank. I guess the idea is that the radiator will always stay filled with liquid - as it expands it compresses air in the expansion tank to make room. If somebody overfills the system there is not enough room, and something explodes. Exploding seems common here. I wonder if perhaps this is due to not leaving enough air in the expansion tank. Or maybe it is user error - if you fill above max you will likely have an explosion since the expanding fluid has no place to go.
So, anybody know why they designed it this way? Is there any over pressure release valve at all in the BMW system? If not, seems like a recipe for disaster.