Diesellieber,

Its the valve springs that close the valves. Although I imagine that when the cylinder fires, the valves are pushed even tighter shut.

Its possible that one of the valves has a slight crack or burn. Or the valve seat could be burned or pitted.

It also could be a broken compression ring.

P E H

After a long winter of moderately difficult starting with up to 90 seconds of glow plug use (usually below 20 degrees), I finally got the SD down to LA and turned it over to Enrique at Mr. MB. He adjusted the valves, did another compression test - everything's fine, it's a very strong engine with a lot of life left in it. Zero stretch on the timing chain - it may have been replaced recently, since the car's been well maintained. Thanks for everyone's help last fall, I plan on putting a lot more miles on this car.