Ok, as a general rule...how much oil should be hanging around the air filter? Granted a tablespoon can be spread around to look like plenty. Just looking for a ball park figure.

The amount of oil in the air filter housing is generally related to the blowby in the engine. Therefore there is no "standard" that is acceptable. An old, tired diesel will have a lot of oil up there. A tight engine will have very little.

Not much you can do about it........either way.

I would say if it is starting to get wicked up by the air cleaner, then you need to address it. Less than that then its just a mess issue and needs to be cleaned regularly.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

I have the same thing happening as in the original post. Oil is getting into the air filter and slowly clogging it up.

My brother-in-law knows his way around diesel engines in trucks, but doesn't know about Mercedes cars.

His suggestion was to disconnect the arm running to the pan with the air filter and have it just vent out into the air. He then said we could plug up the spot at the top of the air filter pan that the arm connected to. I just searched around site for info about how/why this set up is the way it is, but couldn't find anything.

I'm guessing it's a bad idea and that we should just keep things as-is and replace the air filter when too much oil gets in.

I cleaned mine up considerably by disassembling the oil separator in the air cleaner and sealing all the seams with silicone glue. It appears that oil was spraying on the paper filter through these seams.

Ever heard of a catch can? It might be a worthwhile effort for those cars with significant blow by issues.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread

Please say more about a catch can -- how would I set that up? What about the original suggestions I asked about? Are there any major problems that could result from unhooking/plugging things as I described? In the long term, I'd like to get things fixed in the right way but at the moment, I'm just looking for a short-term solution.

Well, I'm not certain how effective the separator that's built in is, but I suppose a catch can might be helpful. I know it works on gas engines just fine. The basic idea is to add a can between the crankcase vent and the normal intake location which contains a filter or baffle that acts as an oil separator. Crankcase vapours and oil enter, but a significant amount of oil gets trapped in the can along the way, and the oil can be dumped out on occasion.

Here's a DIY version. I used something similar to it when I had an old truck with way too much blow by. The catch can helped keep the intake track a lot cleaner. Before installing the catch can, the intake on that truck would coke up with crap and choke off air flow a couple of times each year. After installing a catch can, things improved a lot.

http://www.pbase.com/rsrock/oil_catch_can

The question here is, how effective is the oil separator that's built in to the air filter housing, and is it working properly? Solve that issue before going any further.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread

Forgive the somewhat ignorant question, but is the oil separator the part several inches in diameter at the center of the air filter housing that runs down and has a top that flips up and down? Anyone know threads about how to check/clean/fix?

As I said before, I want to do this the right way but I have a lot of learning to do and I also want to help my brother-in-law learn about Mercedes engines. So, what is the purpose of the way this system is configured and what problems could arise from the 2 original suggestions he had of venting the air away and plugging the intake (as I described in a previous post)?

The oil separator is the round part in the air filter, but please explain what you mean by "a top that flips up and down."

I'm with you on this one... Mine sure doesn't appear to have moving parts. Of course, with a quart of oil in the filter housing, I wasn't really shoving and tugging on things, either. - It's all slippery and icky in there, and I was out of nitrile gloves at the time.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread

I sealed the top of mine with silicone and it improved considerably.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

I don't know if I would call it a catch can as you describe it, but this is what I added to my car. My 300DT has a little over 300,000 miles on it. (At 312500 I get the 500K badge. ) I had problems with enough oil collecting in the air cleaner housing that it would run out the drain hole in the bottom and drip all over the car. I glued a nipple to the bottom of the air cleaner where the drain hole is and I connected a piece of tubing to the nipple. The 1/4 clear tubing runs over to a baby food jar with a hole cut in the lid for the tubing to enter. I mount this behind the left head light next to the A/C drier. I estimate I collect about 3 tablespoons of engine oil every 3000 miles.

To keep the air filter from getting clogged, I use the K&N filter. I find that it tolerate the oil saturation a lot better then a paper filter can. When I rebuilt the engine some day and it is all nice and tight, maybe I will switch back to a paper filter (Wix of course.)

I like the idea of sealing up the oil seperator. I will have to try that.

TimK

__________________
EPA 609 & 608 HVAC Certified
_________________________________________
83' 300D Turbo - 300K + Miles
00' 1.9L TDI Beetle
85' 6.5L Turbo, GV-OD, GMC Suburban,
67' 2.5L Diesel NA - Land Rover Series IIA

Here's what you do if it's so cold your diesel fuel gels. Smear some on some toast and stay inside until it warms up outside.

You're in Washington? Howdy, neighbour!

Yeah, that's not exactly a catch can, but hey, if it keeps oil off of the motor, it sure can't hurt. That's certainly worth seeing a photo of.

I really must post photos of the air filter that came with my car. It's the wrong size, and it's soaked in oil. I'm sure it could win an award for nastiness. I'll have to investigate the oil drain tube when I head out to work on it tomorrow. The engine is just dripping with oil beneath the filter housing despite a degreasing several weeks ago.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread

The drain hole in the bottom? There isn't a drain hole in the bottom. There's three holes for the supports, and a nipple that mates with the oil return tube that runs down past the turbo. Maybe the nipple is broken off? Or just not mated into the return tube? Or maybe somebody removed the oil return line becaue it was leaking down at the pan? If broken or not mated, or just plain missing, yeah, you'll get oil all down the side of the engine.

Seems to me if you replumbed the oil return back in, then you wouldn't need the catch jar nor to remember to empty it.

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.