Hello:
I have a 2.6 w/143k. New guides,seals, basically rebuilt head.No leaks! I'm using a qt of oil about 900 mi. Any ideas? None of my previous 8 MB ever used oil. When I worked at BMW they said 1 qt a 1000 mi. was acceptible- MB says what?

A quart in 1000 miles is acceptable by the book, but not for me! Replace your oil filler cap if you have not done so -- you will leak an astonishing amount of oil there, and the only real clue is oil standing in the recess. Only leaks while driving as the oil gets flung up onto the cap. Won't leak at idle, and the oil runs off and disappears fast.

Find out what clearance the machine shop left for the valves in the guides. I've had several problems with seriously excessive guide to valve clearance (notably valves so loose on an OM603 head that they rattle in the guides without springs installed). You should have essentially zero clearance -- if the valve will go into the guide with hand pressure and close under spring pressure, it's fine (after all, they don't wear tighter!).

I would guess you have excessive clearance, so you are blowing exhaust up the valve stems each exhaust stroke, causing excessive blowby, and the vacuum on the intake pulls oil in. Have someone watch when you start the car in the morning -- a small puff of blue smoke that clears instantly is loose valve guides or improperly installed seals.

Also check for a front timing chain upper cover leak on the passenger side (the low end). The M103 is notorious for dribbling oil there, and you won't see much of it in the driveway, it really only leaks on the highway.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!