Newkid:

Replace your oil filler cap, it's not the cover that's leaking! Cover only makes a mess, if you are using a quart in 400, I'd bet the oil filler cap doesn't seal.

BigBenz:

Replace both valve cover gaskets. The only time you smell buring oil is when they leak onto the exhaust manifold. They are probably so hard they will break when you take the valve covers off!

Clean the cover and the head with solvent, they must both be completely dry when you install the new gasket. Put gasket on the cover and put cover in place, making sure the gasket is still on (it tends to fall off when you flip the cover over), then lift the cover an inch or so and slam it down on the head. Repeat until it makes a solid "clap" rather than a dull "thud" -- you will hear the difference. Then tighten to 20 INCH lbs on the bolts. No leaks. Any oil on the head or cover, the blasted things will leak immediately!

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!