PeachParts Mercedes-Benz Forum - View Single Post - Thoughts On Overhauling 200D (OM621) Engine

Squiggle Dog · #3 02-04-2011, 08:58 PM

Quote:

Originally Posted by Carpenterman

Hey Scotty. It's my understanding that one tooth on the cam sprocket is 18 degrees. So something is truly goofy. Maybe somebody installed an offset key the wrong way, although I still don't know how it could come out to 9 degrees.

Let's see. They could have advanced the chain one tooth, retarded the sprocket 4, 5 or 6 and then the chain stretched another 5, 4, or 3 degrees. That would give you your 9 degrees advanced.

Somebody has evidently screwed with the timing before you. Pull the sprocket and see what's going on with the key/keyway. Perhaps you should then do the valve lift timing method to get an accurate timing value. Then go from there. Be careful with the chain timing so you don't interfere with the valves.

Seems to me if the car starts, has good power, and is not burning oil, then you've got a good bottom end. A compression test will tell you alot, for sure.

Your IP is timed correctly, right?

I was surprised to see the extra notches on the cam, and even more surprised to see a reading of 9 degrees BTDC on the crank pulley when the factory notches on the cam are lined up. It also seems that the lobes on the camshaft are opening the valves too soon.

If a normal chain is supposed to be at 9 degrees ATDC, then having the camshaft off one tooth could put it at 9 degrees BTDC, I think. I am interested in moving it one tooth and taking new readings. I really think that the cam is off one tooth. I've checked for chain stretch on other cars before and this one is weird. I suppose I should buy a dial indicator.

The injection pump was drip timed to 26 degrees BTDC, as specified in the factory service manual.