Whenever I check under my hood (for whatever reason!! :p ), I notice that some oil has accumulated around the cranckase filler cap. Thus, my cap seems to have a little leak.

What does this mean? Anything? The system is supposed to be pressurized... correct?

Thanks!!

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Time to get a new one. The last one I bought was about 5 bucks right from the MB dealer. I think one size fits most German cars.

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When I close my eyes, and inhale, I can smell No. 2.

Ok, but what does it mean if you the cap is leaking?

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

If the cap is leaking it most probably is just worn out. New ones are cheap so try replacing it. That is probably all that is wrong with it. If the leak continues with the new cap then get it looked at. I don't know what would cause it to continue leaking with a new cap if it does.

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Jason Priest
1999 E430
1995 E420 - retired
1986 420SEL - retired

Glad you asked the question.. mine is doing the same thing. I get oil around the cap but not enough to affect the level on the dipstick. I was wondering what was causing it and the only factor I deduced was the cap.. but was afraid it might be some bigger problem. hope changing to a new cap will solve the problem.. I haven't replaced mine yet, but will soon. Thanks guys.

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Nello Tare

1982 300D (266,001 mi.) looking and running great

Previously owned:
1976 450 SLC
1983 300D
1976 300D
also
1982 Jaguar XJ6 (loved, but gone)

Had the same "leak" on the 4.5 a while back. One evening I was perusing the parts inventory on PartsShop (OK, I was bored) when I found replacement oil cap seals. Cost a whopping .30 cents, changed the seal and the seeping leak on top of the valve cover was gone.

You might be able to correct this on yours for even less than was mentioned, if the seal is available for your cap.

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Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

I'll check for that seal, thanks Mike.

Well I know that the cap/seal is leaking! I may have not made myself too clear. For example, what is the purpose of the cap? If not to only contain the oil in the crankcase, but hold pressure too? So what would happen if you drove without an oil cap, pretending you didn't care about the loss of oil, but the oil pressure?

Sorry this is kind of confusing!

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

There is no such thing as a "sealed" oil system on an "open" sump engine. New Mercedes come close with no dipstick. Some ventilation is required due to varying AIR pressures in the sump (downstroke, volatile substances,(ie. gasoline, argh!!), blowby, etc. PCVs do this with positive case ventilation; in the old days the oil filler cap was called a "breather cap" (breathed right into the smog ). The oil filler cap seal is to keep your engine clean; nothing to do with OIL pressure; it does seal AIR to let other emission control devices deal with that. Never saw a car that sooner or later didn't have some seepage from an oil filler cap (no matter how small an amt.).

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Thanks for clearing that up!
I was just curious because I hear of the term 'oil pressure' and thought... well, you know.
Thanks again.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)