I was just checking the condition of my air filter today ('67 w108 250se) and for the first time removed both inner segments. Things looked pretty good except for a brown oily sludge right at the bottom. Is this normal?
Not knowing quite what to do, I wiped it out with a towel and put a nominal amount of clean oil back in the bottom...
I did notice that there is a line going from the top of the engine to just in front of the intake manifold; is this designed to deposit oil through the filter so it can collect dirt more easily?
Vehicle: 1986 190E 2.3-16, 1992 190E 2.3 and 2007 GL450
Location: new york city
Posts: 790
That particular six cylinder motor was a foreshadowing of engine technology for the next forty years.
The system you uncovered is the positive crankcase ventilation system and part of that system is a pipe running from the valve cover to the air cleaner. Gases from the motor's interior go through the tube to be burned through the intake.
Oil bubbles up. However, today's drivers use synthetic oils which are much slipperier and thinner, and if that is the kind of oil you are using, then stop. The car requires a natural oil with a specific viscosity for everything to work right. Also, remember that the valves in this car required leaded gasoline to lubricate their metal-to-metal seals with the aluminum head. Unleaded fuel can cause an incomplete seal between the valve and the aluminum head causing oil to spit up into the head and through that tube and unto the intake.
It was a marvel of the time: a six cylinder cast iron block with aluminum head; overhead camshaft and aluminum pistons. You know very well the power output is enormous and the sound and feel of that motor is like a trip to Mercedes storied past. The massive body that engine so easily pulled around was also a nostalgic experience. Truly a tank with a 110 mph cruising speed.
Thanks for your response lomtevas, If she ever sees 110mph i'll be a happy man!
I'm using 20w 50 mineral oil, and high octane unleaded with a small amount of additive every couple of tanks (just 20-30mls of 2-stroke oil as advised by my mecha nic).
You're right, it's certainly an interesting engine. So am I right to deposit some oil in the bottom of the filter, or should I just wait for it to accumulate naturally?
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