thanks again for the insight..I wish I had done this job when I changed the pan a few weeks back...oh well...it is a PROJECT car..LOL

Cleaning valve in place?
 

Since the replacement valve is no longer available as a stand alone product , are there cleaning agents could be used to prolong the life of the valve?

Hammerwerfer

Yes
 

I most often use spray carburetor or brake cleaner.

If the valve is removed, I have used kerosene, diesel, and many other chemicals.


.

Do all 617 equipped with this check valve? I have 85 300D turbo, Californian version. I couldn't find any check valve in there, after opening the oil pan. Unlike in Dave's picture(#12), it's just an empty hole. It wasn't in the oil pan and it wasn't on the ground either.
Thanks

The 85 kali kar does not have the drain tube going into the upper pan. the 85 Federal version does have this drain tube and Check valve.

Your 85 has the Air Filter behind the R/F Headlight. all the other Turbo W123`s 82 - 84 and 85 Fed have this drain tube.

If you notice the tube from the Valve Cover to the Air Filter has a piece 1/2 way in between that splits off to the air intake to the Turbo. this gives it the suction it needs to pull the blow-by gasses out of the engine. some get into the air filter housing and make a mess in the bottom of the housing.

Charlie

Thank you Charlie. That's the 1st difference I've learned among 617 engines.

Blast From The Past
 

T.T.T. .

I just discovered this thread 3.8.2019, thanx fellas .

FWIW, the fiber discs in these check valves don't like carby/brake cleaners, better to use Rollgay's SAMS CLUB de greaser or 'AWSOME" products instead .

? Are Dave & Shell (?) still here and driving old Mercedes' ? .

Thanks for finding this old thread. I thought that drain tube has a check-valve since I felt it pop open when I blew slightly on the drain tube (via a rubber hose). I wonder if essential. If minimal blow-by, there shouldn't be high air velocity and resulting pressure drop in the PCV tube, so oil mist that is captured into drops on the tube walls should run down into the pan under gravity. It seems the factory design allows build-up of oil in that tube when running, then when the engine is off, the valve will pop open under enough liquid oil "head" to drain down.

My 1985 CA 300D engine has a unique design. There is no oil separator, just a rubber Y which lets oil drops/mist flow directly into the turbo inlet duct. That gunks the compressor wheel. There is no port for an oil drain on the upper oil pan. My 1985 now has an earlier engine, but I kept the frame-mounted air filter (no oil separator). I ran that tube from the Y to the oil drain tube so it doesn't gunk the turbo. I then did the same in my 1984 300D, since I prefer the frame-mounted air cleaner (engine filter brackets shake and break).

Others have plumbed an after-market cone air filter on the turbo inlet. They plumbed the PCV tube to an after-market "oil mist catch can", which many gas turbo tuner guys use (buy on ebay). I assume they drain oil from the catch can periodically and perhaps pour it into the engine (or pour into used oil recycle jug).