Do NOT get talked into engine work because of an oily air filter
element. My '80 300SD had this problem for some years until I sealed the
rim of plastic top of its cyclonic air / oil separator. The plastic
warps and allows oil to spray on to the air filter element; this fixes
it. Sounds like a big job but is quite easy.
Remove the air cleaner's cover as you would to change the air filter.
Inside is what looks like a small "can" with a plastic top that has a
hose connection to the valve cover. Its top is held in place by two
metal tabs, gently bend one or both of these up until the plastic top
can be removed. Note the top's orientation before lifting it out.
Apply Permatex to the top's edges that meet the "can" inside the air
cleaner. Replace the top in the correct orientation and bend the tabs so
top is tight on its "can."
Install a new air filter if the old one is badly oil soaked and close it
This will reduce the oily air filter problem by 98%.
I looked at the air cleaner compartment. The mix chamber is not inside but
under the Air filter compartment. It's held down by three nuts. Naturally
two of them are broken and that is what holds the air filter close to the
intake chamber, letting I assume, more of the oil in. I believe there is
blow by but not sure if that matters all that much, This car runs very nice
at 80. Drove it all the way from Michigan to California going 80 almost all
the way. So maybe I will find another shop to work on my car.
put in a new air filter and drive it.
if it rattles <like mine> at idle get a bath towel <folded> put it on
the top of the air cleaner and close the hood.
worked for me on the noise issue.
the case, minus a few cans!
Case -- I like it! A pretty well-known MB guy up here in Wisconsin (the late
Randy Durrance) suggested fitting an old shock absorber bushing between the
air filter housing and the valve cover to reduce the vibration. The towel,
though, is a much simpler, more common-sense approach.
The placement and stability of the air filter housing in an OM617 engine can
be a big factor in oil leakage from the return line from the oil separator
to the oil pan. It can also go a long way in preserving the air filter
mount, which is a known weak spot on these cars. I have two W123s; one has a
broken mount; the other has been welded.
. To quote Monty Burns and a legion of '70s stoners....excellent!
Talking about air cleaner mounts, I'm going to the dealership tomorrow
to pick up some of the rubber mounts that hold the air cleaner housing
to the bracket. One of them is broken again. At least this time the
bracket is still in one piece. I concluded that the next time the
bracket breaks, I'm going to have it welded with extra pieces of metal
added to reinforce it.
Also, on the bracket, I noticed there are two sets of mounting holes
for the rubber mounts. One set is slightly forward of the other set.
When the last mechanic put the bracket in, which was new, he used the
holes which position the air cleaner slightly back. Couple of years
later, one of the mounts tore out of the bracket ruining the threads.
So, I repositioned the mounts, using the forward set of holes. This
seems to have worked better, as I've only lost one mount in the last 2
years and that was a rubber seperation, everything else is still ok.
Not sure why the bracket has two set of holes, unless MB knows what a
piece of crap it is so they give you the other set to use just in case
an oily air filter. An independent mechanic garage told me that there was
'blow-by' and that a re and re of the engine was definitely, no choice, in
order. My MB dealer told me to hold off and simply replace the filter more
often. I sold the car to a taxi driver who used it as an taxi at 260k km.
I guess, the point is, don't worry about blow-by and replace the air cleaner
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