Okay,
Got one for ya' all.
I have been chasing this issue with oil out my wastegate drain since I got the 81 SD. Frankly it has been pissing me off... recently the problem seemed to have gotten worst whguile on a long road trip so I have been trying to isolate the source because I do not want to pull the head and replace gaskets unless I know it was a cracked head or bad gasket as exhibited by blowby or rebuild a perfectly good turbo to see if it is blowing oil. Anyway you get where I am coming from. So let me tell you what i have done.

I tried to remove the idea of blowby by running the crankcase vent tube under the vehicle because I originally thought this was the source of the excessive amount of oil that was showing up in my air filter housing. I mean the air filter is soaked on one whole side.

So witht eh tube rerouted I ran the car up a good long grade and looked under the air filter cover and there's oil everywhere, including downt he throat of the intake. Hmmm, obviously not coming from the breather hose.

So, thinking that I might have a bad check valve at the bottom of the cyclone drain tube I put the old MityVac on it and it holds the max vacuum I can pull with the MityVac. Seems to be working...

Then I thought maybe I am pulling a sufficient vacuum with the cyclone vent tube in the intake throat that I pulled the vent tube off to see what would happen. In fact, I pulled the whole top off the cyclone just to make sure there was no vacuum created by a venturi effect int he vent tube.
Drove up the hill climb and there is oil again all over the inside of the air filter housing. Blotches splattered here and there. Obvious source is the cyclone drain tube since the cyclone has oil splattered around the sides and puddled in the bottom.

When I noticed this I thought maybe the check valve had broken open or stuck open so I tried to test the check valve again and it appears to be holding like before at max vacuum that my MityVac can pull. Just because I decided to hit the throttle a couple of times and when I did all of a sudden the oil shoots up my MityVac hose. Now remember I had the breather located under teh car so this could not have filled the cyclone drain pipe with oil but it obviously was almost completely full as it shot all the way back up the tube to my MityVac itself.

This leaves me completely and utterly confused/pissed.
BTW - The 3' blowby bypass pipe that I rigged only gets a few drops of oil draining out of the hose after having sat for 10 minutes or so and this is after a hard hill climb so I don't believe this is excessive blowby. The car also never uses oil in normal driving and starts after the first glow cycle at 12 degrees.

So, just for the sake of argument let's rule out blowby then unless it can somehow force all this oil up the cyclone drain tube yet not show any signs of blowing oil all over the place out the breather.
So I come to the big question, why in the H_ll would I get oil blowing up and out of the cyclone drain when the engine is under heavy load?

BTW - these results also rule out what I thought might be a blown turbo seal. There is no way it could shoot oil back up into the air filter housing and neatly hit the cyclone too... This was also one of the considerations I had going into all this though.

Any ideas on this guys?
Could the turbo pressure be leaching into the crankcase and blowing the oil back up the tube? But wouldn't that also manifest itself in some heavy blowby since the crankcase and breather have no restrictions between them?
How about possibly that the cyclone drain is pushed too far into the oil pan and is below the oil level? Then when the pressur ebuilds in the crankcase it creates a pressure increase in the oil pan causing the oil to try to escape the pan via the easiest method (doesn't make sense with the apparently functional check valve but maybe it is weak and wil test with vacuum but the pressures are far greater than I can apply?).
Or how about if the check valve is releasing every time you back off on the throttle a little and the increased crankcase pressure is then shooting the oil up into the cyclone? Could you create enough of a pressure differential by backing off the throttle suddenly?

I'm fishing here and to add to the problem there is no information in any of my manuals about the replacement of the check valve. Not even a mention of it when they talk about the upper oil pan. They talk about the drain tube but not the valve...

Thanks for reading my rant...

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Were looking at the same problem.
I will have to replace mine and I know it requires removing the oil pan to do it. Already have the gasket with this potential job in mind.
The amount of suction in the intake cane be quite a lot so I could see why the oil is sucked up into the intake.
Another thought that has crossed my mind is the air filter I have. It is a Purolator not a Mercedes. If it is restricting the air flow then the air has to come from somewhere and up the drain tube is a possibility.

Dave

Here is the diagram of the air breather system. Notice item #7 the check valve.
http://skinnerbox.steaky.org/Service/W123/w123CD2/Program/Engine/617/01-040.pdf

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

Sounds like you have a crankcase breather blocked...along with the hose to the oil seperator...and the pressure is venting at the point of least resistance....the drain from the oil seperator.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Doctor,
The breather blows pretty good when the car is hot. I checked it when i did the valves and it is clear. The hose is clear too so that ain't it. I wish it was that easy... Was it you that had the leaking wastegate also?
I'm betting that this is a fairly common failure that never gets diagnosed and folks just live with the leak thinking it is a turbo seal or seomthng big that has failed.

Dave
It was your post that got me really going on this. I find it hard to believe though that ther could be that much suction with a new air filter and the tube off the connector to the front duct.
I searched my parts file and see a listing for both the check valve (617 018 00 29) and a part called a "clamping sleeve" (007346 020001). Both combined appear to only be about 16.00 from the dealer but I have no clue what the clamping sleeve is. It is displayed along with the check valve though so maybe it is what holds the valve into place.

What has me going is the fact that the MityVac tests my valve as good but yet under certain conditions it obviously is not. Theoretically a valve like this would only open one way so the weight of the oil on top of it would open it but why mine would test good yet allow oil to climb that tube is a true mystery to me. Especially when there is no oil being introduced via the tube.

If can think of any other tests to perform, I am on a mission and am willing to try just about anything to figure this out as long as I can do it.

I love driving this car but I cannot leave a puddle on every driveway that I visit. If I don't figure this one out I'll probably sell it but I hate passing problems on to another owner (like all the POs have done to me)...

If you do yours please share the experience. If I had any indication how to deal with it I would probably go for it this weekend just to see. $16.00 I can afford to throw into this, a new turbo (which is what I thought I needed) I cannot.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

No I did not have the wastegate problem.....I had the crancase ventilation restriction causeing backpressure.

I can't see a turbo seal even remotely casuing this issue.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I paid all of $500.00 for this beauty I'd hate to spoil the experience and put some serious money into it...

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

If you can solve this mystery it will probably solve a series of similar mysteries that have appeared on the board in the past. People have reported high oil consumption and clouds of smoke with no explicable cause. I have speculated myself that it has something to do with that check valve. Have you poked anything down the pipe to see if you can feel any oddities with it, particularly with the engine running?

__________________
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

I noted an older thread where the owner replaced that pipe with hose. Probably a good idea to just make removing the turbo easier..

I can blow air through it and it gurgles/bubbles so it is open that way.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Thinking about the design of the engine. Or just a way of talking out loud.

Your correct in thinking the oil is coming from the cyclone drain tube. Since you have disconnected the valve cover tube. The only sources of oil in or near the airfilter are the turbo and the oil seperator assembly. The turbo is creating a suction into the turbo so I dont' see how the turbo could be providing the oil in the inner section of the air filter. In your oil seperator system, you have disconnected one of 2 sources to the oil seperator. The only other access point is the drain tube.
The check vavle could be worn and not moving upward to block the oil. If it is a ball check valve with a spring, either the spring could be broken or the ball could be damaged. Puting a Mityvac on it may be producing enough suction to cause the unit to work but the typical operating engine does not produce that much vacuum so it will allow the oil to bypass the check valve. A little more vacuum and it closes.

The only other thoughts I have are
1, Some bad piston rings. Which would allow a lot of blowby to move down into the crank case and up the oil seperator drain tube. But this theory is not very good since you mentioned very little bypass at the valve cover.
2, Your oil level is not correct and liquid oil is right at the check valve. But this again does not hold much water in my mind.

So this leads us back to the check valve. I have looked at my 617 service manual and the area is described in the upper pan removal section. but it does not mention R+R the check valve. This may be incorporated in the upper oil pan. You, however mentioned the part is available so it ust be replacable.
I will run to the dealer tomorrow, I hope and talk to the W123 specialist. See what his input to this problem is.

This job description shows the oil pan removal proceedure.


http://skinnerbox.steaky.org/Service/W123/w123CD2/Program/Engine/617/01-310.pdf

In the middle of the 2nd page is a closeup of the upper oil pan turbo and seperator drain tubes. Your post mentions 2 parts Item 7 is the check valve and Item 8 is the tube you probably mentioned. The "calmping sleeve" is probably item #8 which is the sleeve that has the Oring and the drain tube sits over. To replace the check valve, IIRC, the oil pan must be removed. The #8 item, I will call a tube, looks like it is pressed or hammered into the upper oil pan. Just like the oil dipstick. Not sure since the MM for the 617 never mentions it, again I will ask the mechanic tomorrow

Dave

PS to add info to this post. I just replaced the turbo oil drain tube Orings (upper gasket, middle and lower Orings as well as the oil seperator drain tube Orings) so they are not the oil leak problem in my car.

__________________
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car

If you have oil coming up the cyclone drain tube you have a pressure differential between the crankcase and the air cleaner. Have you check the oil return passages in the head to make sure they are not blocked, creating too much pressure in the pan? How bad is the air cleaner element? If you have overwhelming amounts of blow by you might try sealing the top of the cyclone and running a vent hose from there to a catch can and run the line from the valve cover there too. Even with copious amounts of blow by these engines can run thousands of miles. If you run them hard with good clean oil they can sometimes get better.

__________________
Bob D.
Parrish, FL
1 SDL, 1 D, 1 TD, 1 Mog

Doesn't the engine breathing allow for any pressure in the oil pan to be relieved by direct venting up the front of the engine through the timing chain area on the front of the engine or does it have to pass exhaust gases (blowby) through ports within the engine?

If it is direct venting then there should never be excess pressure in the oil pan unless you have some extreme blowby which would be evidenced through the breather unless of course you have a plugged breather.

The reason I am still searching is that this oil up the line is only evidenced when I am hammer down climbing a long grade. Theoretically the heaviest blowby would be created from this heavy load on the engine right? Also any turbo pressure that might be leaking into the engine would be worst under these conditions adding to the potential blowby. I just don't see the blowby being that big of a factor though because you have a direct vent through a half inch hole in yoru valve cover so I don't really see how you could get that much back pessure but maybe. although I thought that if you had that much pressure it would shut down the engine.
Could I test this by pulling my dipstick up a little, wrapping it with a rag to avoid a real mess and trying the hill? Surely if the pressures are what is doing it then the dipsick would also exhibit the same symptoms. Although I have no idea if this is actually normal that it would come out the dipstick unde any circumstances.

It cannot be vacuum from the engine intake because I can create a very high vacuum sitting still at full throttle. Engine load has no bearing on the vacuum or would it due to the turbo being spooled up but the engine running at lower rpms? I don't think that makes sense...sorry it's early here...

Wish I could have someone drive it while I sat in the engine compartment and watched this phenomenom...

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

THe only way you can have any significant vacume on the inlet of the turbo is with a seriously restricted air filter. The ventilation of the engine is through the top of the valve cover which goes to the oil seperator.

If that is restricted for any reason the blowby pressure that builds up will try to find any other way it can to escape...be it the dipstick to spewing oil....or the oil seperator drain. Or the main seals.....in my case it was partially activating the IP shutoff causing me to lose power on the highway.....

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I know that "bhd" is not referring to this, but a warning for some folks that haven't seen this warning before may get confused on turbo intake vacuum....

NEVER get your hand near the turbo intake. The vacuum there can be substantial and will take your hand into the inlet, resulting in injury (severe).

Now onto our regularly scheduled show

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Correct...............

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

I went ahead and pulled the oil return line off the upper pan and closed off the pan copnnection with a little hose and some clamps.
I then plugged the bottom of the oil seperator and reconnected everything back up like it normally runs i.e. breather into seperator etc...

I then hit the hills. Two trips up the toughest climb I could find and guess what... NO oil leak!

Now to find out why the oil is getting pulled/pushed up the drain line.
I went ahead and ordered a new check valve and "clamping sleeve", the dealer has no clue what it is for but it is in the same picture so may as well get it. 22 dollars for both parts but if it fixes this leak permanently it will be the best 22 dollars I have ever spent on my cars. They of course have nothing in stock so it'll be next week before I can even think about trying to replace that part. In the meantime though it is such a relief to drive the car knowing that if I park it on a nice driveway I won't leave a stain...

BTW - I did pull the top off the seperator since I have it plugged to see what kind of blowby oil I was accumulating in there and it had maybe 5 or 6 drops of oil. Just enough to cover the bottom of the seperator. Man, what a relief to also know now that not only is my turbo okay but it appears that I am not blowing any large quantities of oil out the breather either.

I'll try to get to that check valve next week if the warm weather holds.

Thanks to all for listening to me and providing input as I try to think this thing through.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique