Because the engine was running a little cool (below 80, usually 2 needles above 80) I decided to pull it anyway. The edge is torn all around. I assume this is not good. I was surprised when coolant starting dumping out upon removal!

I put it back in, for now, and left it unconnected. I will keep an eye on the system, but I suspect other issues.

The only recent change I made was a new 20lbs expansion tank cap. Based on how the upper hose feels and the sound when opening the tank I am certain the old was was bad. Maybe the new coolant pressures are stressing the old system.

__________________
1991 560 SEL / 185k miles
1992 750il / 17k miles - project car