I was doing some work on my 1991 300D 2.5 TD, when I had to pull of the rubber intake tubibg that goes from the airbox to the turbo. This tubing has a hard plastic tube, covered with rubber, that runs from the top of the valve cover to the airbox tube. I am puzzled because the inside of this tube was covered with oil and the tube from the valve cover does not contain any sort of valve in it. On my race cars I have tubes that goe from the valve covers to the airbox, but they have a PCV valve in them. What is the inside scoop on these? Is there supposed to be a valve in there? The only thing I could find in my research is that this particular tube is made intentionally of a hard plastic to prevent it from collapsing under pressure/vacuum. If it does collaps, then the diesel engine will leak oil like a siv.
Thanks for your help!!

Larry, Steve, MB DOC, are you out there???

I know I have a different model diesel than yours, but I'm sure you are talking about the crackcase ventillation hose. My car has a similar setup, no valve, and lots of black oil.

__________________
2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
-------------------------------------
'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

I assume that the hose is there to vent and burn oil fumes, but it seems to me that there should be some sort of baffle or valve there. A while back, I read a [ost on this board about an individual that put a hose from another car in ther, to stop the oil from burning. I searched today, but I was unable to find anything.

CJ-

Are you sure you're not talking about the air filter oil drain tube?

__________________

Scott Longston
Northern California Wine Country...
"Turbos whistle, grapes wine..."

O this hose goes ontop of the air intake tube, from the top of the valve cover.

I have another car(not Mercedes), sometime have this problem, and for that car, it is causing by the oil filter, which between the crankcase ventilation and the hose which connect to the inlet manifold..

are there any such kind of filter ther? if there are, try to check it whether it fail or not.

Although I have a different engine than you do, my 300SD has a simliar tube. It runs from the top of the valve cover to the top of the air filter. Inside of the air filter I have a small oil accumulator, which as far as I can tell collects oil from the hose and dumps it back into the engine. Since my car was designed with an oil accumulator, I have deduced that it is normal for oil to go through the hose. I should note, however, that my engine has a small amount of blowby, so I get more oil in the hose than you probably do.

__________________
Ben

The MBs:
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K

The hose goes to the actual rubber intake track at the airbox, it does not go to the filter. It goes to the 4inch rubber piping that connects the airbox to the turbo. It is not soaked with oil, just a tab moist. I am going to check my airfilter today and entertain the possibility that a clogged airfilter is causing the engine to draw air from the path of least resistance, ie the little tube from the valve cover.