Duke 2.6 and others,
Well the deed is almost done. First I washed the engine with some Gunk engine cleaner and then rinsed it clean at the local do it yourself car wash. Then I drove it home and squirted the fasteners with penetrant and let it sit for a while, until the parts were not too hot to touch. The fasteners came out without much trouble except the one on the front passenger side corner of the engine. This one was hard to turn out, and needed the wrench attached up to the last turn. The old gasket broke in two pieces when I got the cover off, and it seems the previous owner had someone use a little form-a-gasket like material on the semi-circular cut-out at the rear.
The cover was pretty nasty, meaning dirty with lots of brown stuff on the inside surfaces. I washed it with gas a couple of times, then scrubbed it with a toothbrush and rinsed it with gas a few more times. There is a chip in the coating along the gasket seating edge along the rear of the cover, which I sanded to make the transition smooth. Then I rinsed it a few more times with gas, but the staining on the inside kept coming off ever so slightly on my clean rags. I let it dry for half an hour in the sun, and got ready to reassemble.
I used some synthetic assembly grease rated for high temperatures to seat the gasket on the cover and the cylinder head, then put it in place and reconnected the two hoses. I had my 15 year old son help put the fasteners back in, and we slowly tightened them from center to the ends.
We set the torque wrench to 15 Newton-meters, and slowly drew the fasteners up tight, when, the last fastener on the passenger side front corner broke when we gave it its final increment. We took the cover back off, and the fastener stub came loose by giving it a little whack with a punch. I unscrewed it by hand. We then re-cleaned and reassembled the cover to the head, this time using 10 Newton-meters. I took one of the fasteners from the center span and put it back in the front passenger side hole, but now cannot drive the car until I get a new fastener. I will buy 8 new ones though since I am sure they have been over torqued.
Well, thanks for the encouragement and helpful hints. Too bad it is Saturday and I cannot get a screw until Monday, at the earliest. Thanks again, Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)