Mystery part in oil pan

[paulster]

I am in the process of doing an inspection and refresh on a motor from a 1982 300D. In pulling the oil pan, I found the part below. It looks like maybe a 1 inch rubber/plastic diaphragm that was stretched, torn and sucked into the engine, eventually ending up in the pan.

There are two numbers stamped on it: 3887 and 2072. Searching on 3887 brings up a hydraulic suspension pump, but this motor doesn't have one.

I have no history on the car the engine came out of other than it had about 200K miles, so I don't know if it was exhibiting an issue or if whatever this diaphragm came out of was already fixed. I suppose I could run it and see, but I'd rather be more proactive in tracking it down while the engine is out of the vehicle.

So: anyone have a clue what would have a 1 inch diaphragm as part of the oil circuit?

[rrgrassi]

Could it be from a failed vacuum pump?

[paulster]

Possibly! If anyone has rebuilt a vacuum pump on an early 80's Mercedes diesel, can you confirm whether the two small round "check valves" pictured at the bottom of the photo below have a diaphragm that's about an inch in diameter? I can't see past the metal ribbing/valve case in the photos, but looks like it could be a match, and it would certainly be able to drop into the crankcase and oil pan...

[Sugar Bear]

I agree it looks like a diaphragm from a vacuum pump check valve. Do an image search on a vacuum pump rebuild kit and you'll see the parts included.

[BillGrissom]

I doubt the innards of a vac pump check valve. Looks more like a top seal from a bottle of oil additive that might have fallen in when pouring it. Swelled up in the crankcase oil. If you measure good vacuum (>16"Hg), don't worry about your vacuum pump.

[Sugar Bear]

Interesting theory...may be!