I have a 1998 C280 which makes me nervous when I do an oil change. The last time I changed it, the large gasket around the filter cap blew out and I lost an almost total oil change (that darn Syntec is expensive!). I could not get the new gasket to seal, so I cleaned the old one and it worked ok. Alright, just figured the new one had a chink in it or something.

This evening, I carefully changed the filter. Took the old gaskets out, cleaned all the tracks, oiled the new gaskets and installed it. I hand tightened the filter cap. I was watching the seals while the wife was cranking it. Immediately it blew a corner of the gasket out and oil started spraying! I came into Mercedes Shop and read everything I could find. One person recommended torquing it to 18 lbs. Ok, tried that. It ran for about 3 minutes, blew it out again.

Ok, what do I do next? Hand tightening it doesn't work, torguing doesn't work. HELP! Do I just keep using the old oil ring?

(later....)
I put the old gasket back in (it appeared to be much smaller than the new one) and tightened it to 20lbs. At idle, it did fine. After revving it up to about 2500 rpm for a minute, I noticed a large bulge in the gasket and a small amount of oil leaking AGAIN!

Am I not torquing this thing down enough? I have been unable to find the exact torque specs for the oil cap on a 98 C280.


MUCH later!

Ok, now for another "self-answered" post! I will cut this down to the short and sweet. I am an idiot! I went back out (dark now) and pulled the filter "post" out and took the large gasket off. While doing this, the large FLAT area under the gasket appeared to move ever so slightly! Ok, I thought my eyes were playing tricks on me. I wiped the sweat from my eyes and adjusted my shop light for a better angle. I pushed against what I had thought was the "landing area" for the large gasket. It moved again! I then realized that it was ANOTHER gasket! Very flat, too. I removed this old flat gasket, reinstalled the new gasket and snugged the oil cap down AGAINST the metal case (it wouldn't do this before). Cranked the engine and inspected for leaks. NADA

I am not sure how long this "flat gasket" was on the oil filter cap. It may have been there when I bought the car used.

Lesson to be learned here. Be very sure that all old gaskets are removed before attempting to install new ones. This gasket had been in there so long that it was very flat and very hard. It had embedded itself into the gasket "trench" and looked like part of the oil cap assembly!

As I said before, I am an idiot!