Oil coming UP the cyclone drain tube!!!

[Fisherman]

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...

[dmorrison]

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

[boneheaddoctor]

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.

[Fisherman]

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.

[boneheaddoctor]

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.

[Fisherman]

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

[kerry]

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?

[Fisherman]

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.

[Fisherman]

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.

[dmorrison]

Oh boy we may be fighting for the only check valve in the USA. My dealer ordered mine today and said there was only 1. We'll have to see wether there is just 1 or You ordered 1 and only 1 was left when I ordered mine. He did say the "clamping sleeve had to come from Germany.
Talked to the reliable W123 mechanic at the dealer. The check valve is pressed in just like the oil dipstick tube. So It may be some work getting it out. Not hard just cramped. The Dealer also said that the clamping sleeve is probably the attachment point for the drain tube. We looked and could not find any other part number for the connecting tube. So we concluded that that is what the "clamping tube" is.
I do thiink that I'm having the same problem as you are. The mechanic also supported my finding in both my car and yours.
I will ask him when the part comes in if any gasket sealer should be used in installing the check valve. I will treat it like the oil dipstick tube and follow the directions in the manual for that.

Don't forget to order your oil pan gasket. You'll need one to do the job. It might be a good time to change the oil and filter at the same time.

Dave

PS First one with pictures wins. . But then of course a photo essay for the forum is required.

[Fisherman]

That if you didn't need to replace the clamping ring life would be easier but I have a sneaking supicion that you have to pull that upper tube out to knock out the valve.
I can pick up the pan gasket ina day from Phil and I am definately more worried about my dealer parts guy getting the parts.

Personally I'm not too concerned aboput just blocking it off other than having to dump the oil seperator every few hundred miles or so. I was thinking tht if I can get a used drain tube at the wreckers then I will cut itoff and rig up a bottle to the end so I cna leave it conencted and then just dump the botle occasionally.

Anyway, I can wait to see what this part is made up like...

[Fisherman]

Well I got my check valve today...
Interesting, it is simply a plastic disk inside what appears to be a brass ring that is supported by a very light spring.
The clamping sleeve part appears to be a spring steel insert about 3/4 of an inch long that I assume is knocked into place supporting or holding the check valve into place.

Looks like a very, very simple device with no big mystery. It'll be a few weeks before I can make the install. I'll try to update later.

[dmorrison]

Got mine today. The check valve is the same, or appears to be the same as the vacuum pump check valves.
I still need the clamp sleeve. I also ordered the upper tube that the drain tube goes over. Just in case I need it.
The vacum pump uses gaskets to seal the check valve. Nothing is shown as a part in the diagram for this check valve. So I'm curious about the sealing of the check valve against the upper oil pan.

Dave

[Fisherman]

I won't have a chance to tear into this for another week or two.

[Fisherman]

Just drove down to the Bay Area today and low and behold with the drain tube plugged I did not leak one drop of oil out the wastegate.

I can't wait to replace that valve..