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  #1  
Old 12-15-2004, 11:40 PM
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I removed my oil separator!

I put my money where my mouth is and disconnected my oil separator on my 300D. Why you ask? Well the shaking at idle had broken the separator return tube. That tube is $60. The rubber grommet in the air cleaner lid fits so loosely around the inlet to the oil separator that it was allowing grit into the intake. I have tried in vain to get another grommet, no dice, from Phil or the dealer. I capped the return bung on the oil pan. I closed of the top and bottom of the oil separator in the air cleaner housing. I drilled a hole and put a 3/8" brass hose barb in the flat spot on the U-tube intake right before the turbo. I then ran a piece of 3/8" fuel grade hose from the hose barb up to the 90* rubber elbow from the original vapor vent setup on top of the valve cover. I inserted a piece of 3/8" brass tubing into the fuel line and then pushed the fuel line into the rubber elbow. The brass tubing allow a hose clamp to secure the elbow to the 3/8's hose without crushing/closing it off. No more oily muck in the top of the air filter. After @400miles there is no apparent extra oil use or any other problems. I did this because my two other diesel vehicles have similar setups with no oil separators. Looking at pictures of Euro MB's they don't appear to have oil separators either. IMHO the oil separators were a US emissions thing. So far so good. I would take a picture but I have no idea how to post it. RT

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  #2  
Old 12-16-2004, 12:16 AM
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Thumbs down Bad idea...

Quote:
Originally Posted by rwthomas1
I put my money where my mouth is and disconnected my oil separator on my 300D. Why you ask? Well the shaking at idle had broken the separator return tube. That tube is $60. The rubber grommet in the air cleaner lid fits so loosely around the inlet to the oil separator that it was allowing grit into the intake. I have tried in vain to get another grommet, no dice, from Phil or the dealer. I capped the return bung on the oil pan. I closed of the top and bottom of the oil separator in the air cleaner housing. I drilled a hole and put a 3/8" brass hose barb in the flat spot on the U-tube intake right before the turbo. I then ran a piece of 3/8" fuel grade hose from the hose barb up to the 90* rubber elbow from the original vapor vent setup on top of the valve cover. I inserted a piece of 3/8" brass tubing into the fuel line and then pushed the fuel line into the rubber elbow. The brass tubing allow a hose clamp to secure the elbow to the 3/8's hose without crushing/closing it off. No more oily muck in the top of the air filter. After @400miles there is no apparent extra oil use or any other problems. I did this because my two other diesel vehicles have similar setups with no oil separators. Looking at pictures of Euro MB's they don't appear to have oil separators either. IMHO the oil separators were a US emissions thing. So far so good. I would take a picture but I have no idea how to post it. RT
It is not emissions...
Read this thread:
http://www.peachparts.com/shopforum/showthread.php?t=101404
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  #3  
Old 12-16-2004, 12:41 AM
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Let me get this straight.

After I read your description, I understand that you no longer have any oil separation. You are basically feeding all the oil and gasses, from the valve cover, directly into the turbo inlet. Sounds like a high turbo wear set-up to me. Especially, when liquid hits the turbo blades at speed. Also, with this scenario, you may run a very high risk of runaway if their is a condition of vacuum in the turbo inlet.

You can check with the pros here. IMHO, sounds very risky to me. Crankcase ventilation is not an emission feature. It is to keep gases from building up in the crankcase.
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  #4  
Old 12-16-2004, 06:13 AM
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You now have kinda/sorta the same type set up as a '79/'80 300SD.
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  #5  
Old 12-16-2004, 11:23 AM
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SDBlue,
You are correct. I no longer have ANY oil separator. First of all has anyone looked inside a MB separator? Its empty with a small diverter to make the incoming crankcase gases swirl around the chamber. There is a vent line that comes out of the top on the opposite side of the chamber top and takes a 90* turn down pointing into the intake. Thats what you see with the air filter top off. At the bottom of the separator there is a drain, by gravity back to the oil pan. The placement of the new fitting in the U-tube will allow the crankcase gasses to be drawn out as a slight vacuum exists in the U-tube from the resistance of the air cleaner and the sucking of the intake/turbo. This will scavenge the crankcase gasses. Regarding oil drops passing through the turbo. This happens already. Look at the oily mess in your existing air filter housing and U-tube. There really shouldn't be "drops" per se but a very fine oil mist. Its not like I am sucking raw combustion gases straight out of the valve cover. There is a baffle on the inside of the valve cover to prevent liquid oil from being sucked out. I have a VW Jetta with a baffle in the valve cover and the vent goes right to the intake manifold. 300+K and no issues. On my truck the valve cover has a hole in it, no baffle, then a push in baffle and the vent line runs right to the mouth of the turbo. 209K and no issues. As Engatwork pointed out, the 79/80 SD turbos had basically the same setup. I looked at one in a junkyard to check it out. Of course if I overfilled the crankcase or if I had enough blowby there is a possibility of a "runaway" engine. If you looked at the stock oil separator I think you will agree that with enough blowby you could have a runaway with that too. I am monitoring the oil use of the engine. Usually it uses almost no oil. I would assume that if my new breather setup allows more oil use I will see it on the dipstick. Since MB did this on stock engines, my engine is in good condition and I don't overfill it with oil I don't forsee any problem with doing this. Part of the reason for doing this was to do away with the nasty oily separator in the air cleaner housing and the grit that has been getting past the seal at the top of the filter. The other reason is that I am planning on a custom intake/filter setup that I am designing. Not having to deal with the separator makes things easier and looks a lot cleaner in the engine compartment, IMHO. There is no "grave danger" in what I have done. RT
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  #6  
Old 12-16-2004, 12:15 PM
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That and my 300SD has no oil seperator at all, never did, has no place for one to drain unless you remove the dipstick...............
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  #7  
Old 12-16-2004, 08:44 PM
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You do not understand your risk.

Hello rwthomas1
This is NOT a gas engine.
The crank case is under pressure at speed/load, gasses and liquid oil are blowing into the oil separator under pressure, plus your alteration adds direct turbo suction.
With your alteration; 100% of gasses and liquid goes directly into the combustion chamber, a sure recipe for disaster sooner or later.
This is an OM617 Mercedes Benz, please do not try to compare it to a VW Jetta, the technologies are not the same.
The 79/80 SD turbo had a different setup, Mercedes Benz is aware of the possible diesel run away problem, I can assure you there is a difference without having the total crank case vent system schematic in front of me for this year model.
I have looked at the stock oil separator, enough blow by on it can cause a runaway, however, it is there to reduce emissions, reduce crank case oil loss and reduce the risk of run away.
Monitoring the oil use of the engine is a poor substitute for the correctly engineered device.
I suggest you ask mplafleur and Larry Bible how much time it takes for an engine to run away and junk out.
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Old 12-16-2004, 09:05 PM
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I would tend follow Whunter on this as he has far more mechanical experience than most of us..............I have great respect for his judgement.

I've never seen another Benz under the hood other than my own. I can't compare differences.
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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

Last edited by boneheaddoctor; 12-16-2004 at 09:10 PM.
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  #9  
Old 12-16-2004, 09:08 PM
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On the '85 TD my boss has, the CCV tube goes directly to the turbo tube and the air filter housing. No seperator, but I guess the two openings prevent extreme suction from drawing out oil.
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  #10  
Old 12-16-2004, 10:53 PM
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Quote:
Originally Posted by 82-300td
On the '85 TD my boss has, the CCV tube goes directly to the turbo tube and the air filter housing. No seperator, but I guess the two openings prevent extreme suction from drawing out oil.
Seems like I remember that these cars had a seperator in the filter housing???

But let me tell you Mr. Hunter is most correct here, you better vent that crankcase, or you are headed for a real big and expensive suprise before to long. I know something about CCV's, as I designed one for the VW TDI that a lot of folks on the TDI Club forum bought for their cars, to prevent the clogged intakes. One guy running the "elephant hose" from valvecover to can in bottom of engione bay, had the thing freeze up on him and the back pressure built up and blew oil seals, crankcase oil was sucked out to turbo and an self distructed his engine. Here is link to the shop that built them for us on the forum CCV Filter and shows internial design and the filter it uses. And it really works, below is one on my wife's Jetta.


I don't know if they are going to make anymore as the guy that owns the shop doesn't seem to be interested in continuing the project. I have a design for one for my 240D that would be able to be used on any car, but no one to build it.
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  #11  
Old 12-16-2004, 11:05 PM
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86 Sdl

My 86 SDL (126) dosn't have an oil seperator, but my 83 300 TD (123) has one.
I used to have an 80 SD (116), and it did not have one.
Maybe M.B could'nt make up there mind to use one or not!
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  #12  
Old 12-16-2004, 11:07 PM
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Oh here we go again with the MB is a totally different (nose-in-the-air) better engine than the GM or VW. Guess what? I am well aware and aquainted diesel engines. I know its NOT gas! Guess what? All three of my diesels are IDI designs with prechambers, glowplugs, etc. All three have a baffle in the vent system already. Two of them run the vent lines right to the intake with no ill effects. In fact, I have never heard of any of the other brands "running away" due to poor design. MB even used a similar setup previously in the 79/80 SD. If it doesn't work then why did they use it? Do these SD's "runaway"? The only difference I can see in the early SD turbodiesel and my 84 is this breather setup. If this is the only difference then why would one be just an oily mess and the other a "disaster" waiting to happen? Explain it. Anything in between the air filter and the inlet on the turbo is subjected to the same suction. There is no such thing as "direct turbo suction" The original placement of the oil separator subjected it to the same suction I am now using. The only diesels I have ever heard of running away were from severe overfilling of the crankcase oil, a problem with the IP, or one case of very, very, very worn out cylinders/rings causing enough blowby to cause the "occasional" run away. And that car is still driven in its condition. The only thing I might consider is a 240 separator but I will still vent direct to the turbo inlet, if I can find a 240 separator.... Some people have the opinion that this will cause problems. I don't think this will and I don't plan on changing it any time soon. I knew this would start a fire.... RT
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Last edited by rwthomas1; 12-16-2004 at 11:18 PM.
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  #13  
Old 12-16-2004, 11:37 PM
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240D seperator works a little better then 300D's, but not much. I was raised up in my parents trucks stop and I have seen 2 runaways as a kid, (one puked its guts) and there have been any number of VW's & MB's that have runaway engine's when turbo oil seals fail and the think sucks oil direct into intake. We had a runaway DD generator on ship I was on caused by oil seal failure on turbo. A friend had a MB 300SD runaway in his shop as I walked it the shop one day, the only thing he figured that caused it was leaking seals & rings. (he was trained by MB in Germany at factory) He had changed oil & filter along with fuel filters. CO2 was the stopper on the engine and no engine damage. Matter of fact I saw the same car today still running fine 4 years later.

On all diesel engines & gas engines the CC is vented to somewhere, and if you seal off that vent it will look to vent somewhere else as back pressure builds. It will blow oil out dipsticks, past weak oil seals or rings and one way or the other you will be sorry sooner or later. My brother-in-law took off the CCV on his new '68 GTO and got about 2 miles down the road and romped it and blew out most of his oil out through the dipstick tube. The dipstick dented the hood on the car, I got a good laugh from that one. Dented hood & motor guts on the pavement. This was 1968 in Santa Anna, CA by the way.
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Old 12-16-2004, 11:39 PM
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Quote:
Originally Posted by oldnavy
Seems like I remember that these cars had a seperator in the filter housing???
Nope, when I removed the air filter top, the line just plugged onto a nipple that fed into the open space of the housing. (His is an '85 CA model, BTW.)
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  #15  
Old 12-17-2004, 12:18 AM
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All modern diesels are CC vented by blow-by and not some type of tube. Our MBs & our '02 Jetta TDI is the same way. Where you run into trouble is when you plugg it at the topside and if I read it right you haven't done that so you are safe there. I ndon't think much of the swirl design on my 240 or the ones I've seen on 300's, but it's better then nothing.

The problem with your setup and our older MB's is there is no anti run on flap in the intake as in the newer cars such as our VW. The problem with the flap in the VW is soot will build up and make it stick open and the one time you need it, the damn thing won't work. That's happen a number of time to guys on the VW TDI club forum. Generally the VW drivers were warned by engine not dying as soon as key was turned off and just thinking gassers that it needed some tunning. Ooops!!!

The problem with your setup vs my stock system is the stock seperator does help remove some of the oil, just noot enough. As car gets to using oil it's not thought of by most people as something that might cause a real problem and thought as something causing less power when the reverse is true, oil is fuel and more fuel means more engine speed. The 240 system does do a better job at preventing the run on then you might think also, but even it is rather poor at the job.

Now as far as sorry metal tube and the O rings that seal it, throw that crap away and use a nice clear tube to run from CCV, or more correct term oil/air seperator, to the sump nipple. That was my first mod the the car and it got rid of the oil leaks and dirty air to intake. Pictures tomorrow if anyone want to see that mod, cost me less then $2 for parts. I think it was 9/16 ID tubbing from hardware store, and it has been on the car with no problems for about 6000 miles and 6 months,

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