New monovalve, same exact issues. I am now thinking my fairly new t-stat is bad and at times sticking open. When I have no heat the engine runs cool too. Even the exhaust smells harsh. It was installed last fall, but I think its worth a shot. Not sure where else to look. System is full and purged of air.

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