After investigating some oils leaks, this is what I found out:

-The gasket at the oil filter is causing a leak. Is this common on a 300D's?
-The tube that sits on top of the oil pan (Check valve?) seems to already have silicon all around the area, so the previous owner knew about a leak. What can be done to fix this problem?

Below is the thread with some pictures that might show the problem. Thanks again!

617 engine, replacing the oil separator check valve in the upper oil pan.

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1985 300SD - 167k miles
1992 F350 7.3 (Soon to be converted to 2 tank Veggy/WMO)

Bump

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1985 300SD - 167k miles
1992 F350 7.3 (Soon to be converted to 2 tank Veggy/WMO)

It seems like the link you posted shows the repair procedure.

Are you talking about the O-Ring for the top of the oil filter cannister?

The tube that drains to the oil pan is common for leaks. Remove it, replace the upper gasket, O-Rings and grommet. Its a pain in the arse but can be done.

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91 350SD
14 F150 Eco
19 Fusion Hybrid
11 GT500

The oil check valve is, I believe, down below where the drain tube from the air cleaner terminates. The seperator is up in the air cleaner. Dave Morrison goes into this in detail in the post that you linked to. I read that DIY article about a year ago and if I remember correctly, Dave removed the oil pan to replace the check valve. Quite a messy job but I believe it solved his problem. I have an oil pan gasket on hand but have not ventured into that job yet.

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85 300D 75K Anthracite Grey 0-60 in 13 seconds **For Sale**
84 300D 333K Black (The Velveteen Rabbit) 0-60 in 14 seconds
00 Toyota Sienna 208K (Sold)
15 Subaru Outback 43K
11 Subaru Outback 67K
98 Ford Taurus 100K (Gertie - Was Grandma's - drove it to church and shopping - really) Daughter's car now.
30 Model A Ford 2 Door Sedan (Sold) 0-60 in . . . Never reached 60

There is an o-ring on the check valve nipple. Same size as on the air cleaner end of the drain tube. Also same size as on the oil dip stick.

Which gasket?

Yes, the gasket between the oil filter housing and block is a common leak point. Try tightening the bolts before replacing the gasket.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Thank you everyone! Great information!

Someone else mentioned the check valve; Where can this be purchased? Where can the upper gasket and grommet be purchased? I already have some spare o-rings, since they are the same used in the oil filter housing.

THANKS AGAIN!

__________________
1985 300SD - 167k miles
1992 F350 7.3 (Soon to be converted to 2 tank Veggy/WMO)

This may be helpful.

Bodyart27's write up on his disgustingly immaculate 300SD. You should see this car in person.

Tips & Pics - 617Turbo oil drain, check valve, oil pump pickup boot/strainer, sealing

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91 350SD
14 F150 Eco
19 Fusion Hybrid
11 GT500

That information might not be so great. The air/oil separator drain tube seals with nothing but an o-ring at both the upper and lower ends. I would suggest that you replace the lower o-ring before you conclude that the check valve is the culprit.

Most likely, the previous comments about a gasket and grommet were made in reference to the turbo drain, not the air/oil separator drain.

Lastly, the o-rings in question are not the same size as the ones used in the oil filter. They are the same as the oil dipstick seal.

here both the filter gaskets can be had from phil.

and the orings, gasket and grommet from the turbo drain tube. you should verify if the turbo drain is leaking(larger), or the oil separator tube(smaller), or both.

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1984 123.193 372,xxx miles, room for Seven.

1999 Dodge Durango Cummins 4BTAA 47RE 5k lb 4x4 getting 25+mpgs, room for Seven.