I ran the car (1982 300D with 200k miles) for 500 miles (mostly city, some freeway), average trip is 10 miles or maybe less. Here are the results:
Oil level dropped 1/2 quart (16oz). During this time I fed the blow by return pipe into a can, noticeable amount of smoke was coming out from under the hood. About 4oz was captured in the can. Any suggestions? External oil leaks (minor) don't explain the excessive oil consumption. Exhaust pipe has lots of soot.

Thanks

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1972 450SL
1982 300D Turbo

One thing missing from Brian's equation, is the oil that gets on top of the piston, past the oil ring, and is burned. Blow-by is only a measure of what the cylinder loss is in one direction. Also, with blow-by, there is some oil lost to vapor, that must be condensed out of the hot air, before it can be measured. The " smoke from under the hood" would qualify as oil smoke. A decent "test" nonetheless.

so the oil that gets by the rings is coming from the oiling slots on the piston right? this may seem strange coming from me but i have never talked about it before. so that is the source of blue smoke on any car that is smoking from wear, right?

and if it is not worn, the oil from the oiling slots is simply swept back into the pan, right?

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Don't forget to consider valve seals.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Thanks Brian,a lot of tests are not absolute but many provide indications. Anyone designing them for consideration is very much appreciated. Far better than nothing or just absolute guesswork as an alternative. Plus sometimes they can be refined into useful comparisons. This test for example screams for baseline information from other engines. The engine does create some small vacccum component. I believe or it would be unable to suck air and blowby through the air filter when pipe is connected to the filter housing. When pipe was just directed to container even that small component was gone although perhaps not too signifigant or perhaps it is. . But totally diluted by the vent pipe termination outside the filter housing. The same test made by construction of a real oil trap installed on that line might or might not give a better indication. Should though I imagine. I surmise the seals in the turbo are still suspect though. Certainly not ruled out. Could easily be a combination fault of various problems making an overall contribution. Sad their is no existing refferences until a few more try it and we get a guildline going? Have to wonder if any amount of oil would be collected from one of my engines?

You can have good compression rings and poor oil ring function at the same time. The poor oil rings will just not scape the oil off the walls and it lands up being burnt. Or it is just going by them at a greater rate than design. Or even worst the excess clearance in the piston lands enables them to become minature oil pumps. At a thousand miles per quart you just might notice a difference in tailpipe emissions if oil is being burnt primarily. But I suspect not very much and you would have had to own the same engine in better condition to even risk an evaluation based on that. At 200-400 miles per quart the emissions become pretty obvious. your consumption rate appears to be increasing pretty fast. One might consider driving it for a time just adding oil until it is more clear cut. That is if engine is starting and running reliable right now. Another quick and good test in your hot part of the country is to change oil to a straight 40 weight or 50 weight oil. Perhaps a gallon of each if it makes you feel better. If oil consumption drops in half it probably is the engine rather than turbo bearing related. Pete is also right the seals could be making a contribution as this engine has had one ring job already and if they did not touch the head those seals might be getting tired as well. Again this might be a problem partially caused from a little deficiency here and there. Using a thicker base oil will define it somewhat as a diagnostic tool. A straight 40 or 50 weight has so much more viscosity than a multi grade oil in actual service it is almost unbelievable. Really helps seal thing partially up. If blowby drops way way down you pretty well have your answer. If nothing else it should rule out or condem the turbo seals as a major contributor in my opinion. If it is the turbo seal I would expect only a slight reduction in consumption with the heavier oil. If it is the engine I would expect a doubling of miles per quart burn ratio perhaps even more. Post some information down the road for everyones benifit. There is another test as well come to think of it. When turbo is cold take off ductwork and feel for excess play in bearings. Not conclusive but really worn bearings are harder to keep the seals working well. At least everything mentioned is pretty cheap to do with no expensive or difficult substitutions in the program. I like cheap somewhat meaningful indicating tests myself. Perhaps not the necessity to do them though.

Well, the test confirms that you don't have excessive blowby resulting in high oil consumption.

I agree with the possibility that the oil rings may be shot with the compression rings in good shape with the resultant oil consumption bypassing the rings. But, I have serious doubts about this. Why would a well maintained engine have just the oil rings go south?

No, far more likely that that engine and my SD and '86 SDL share the same problem. Excessive oil consumption via the turbo. The SD is going through about 1 quart every 1500 miles and it has perfect valve guides and seals with very little blowby and very good compression. The only remaining possibility is the turbo.

When the turbo was off the vehicle, I found the wastegate diaphragm housing filled with oil. That's got to tell you something..............

There's a simple test of the turbo seals. Disconnect the oil line from the turbo, plug it, and drive it for a while and see if the oil consumption drops.

(NOTE: This IS a joke!!)

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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 know someone who performed this joke on a Saab 9000 Turbo once. His compressor-side seals started dumping oil into the engine, and in a fit of inspiration he cut a piece of cardboard to block the oil intake into the turbocharger and kept going.

The oil leaking problem was solved, but the pieces of compressor turbine in the intercooler and into the intake of the engine posed larger problems in the end.

........Where's your sign??

I was also going to mention your though Brian but it occured to me that if the oil was going through the air filter it might accumulate to some extent where you found it in yours. At 1000 or 1500 miles per quart I suspect just a seepage rather than a gusher type of situation if present at the turbo bearing. Probably one can only base finding oil there as a diagnostic tool if air cleaner filter shows no evidence of passing oil. His does unfortunatly. The heavier viscosity oil should tend to separate the possibilties somewhat. Also on the containment vessel he used. At highway revolutions it might be hard to contain the essence of what is coming out that pipe. A tremendous vapour fog might be emiiting. This is not disscusion for arguments sake either as I just try to keep an open mind with limited intelligence. A good engine with no excess blowby driving the vapours should have only collected smoke pretty well. Plus what is going out his tailpipe is also a total unknown. Perhaps something can be learned from this situation hopefully. Whatever indicators can be though up or passed on that reduce the so called guesswork are really appreciated as it is just not good economic sense to frequent service places and this site is the best place to prevent it I have ever experienced. Remember I am not a working mechanic and this is a hobby to me. While others depend on this site for their daily transportation. There are so many smart people on this site plus guys who donate their everyday work experience as mechanics as to be unbelievable. In our area of the country what mechanics are generally compansated for their time versus the actual bills presented is almost nothing short of criminal. Sorry about wandering so much.

In fact, poor oil control can actually improve compression.

You want to know of a good test with results that you can actually measure?
A compression test.

Compression is what actually matters in this whole equation. Yes, more blow-by typically means less compression, I hear you. But, you are worrying about the wrong end of it. You can have LOTS of blow-by and not have it matter to engine performance as long as your compression is good.

Remember, they designed these engines with the PCV system with oil condensor already built in. This is what the car does.

A compression test is the only way to know the true health of your engine.

Lots of info and read it quick, will reread later.

- Thicker oil?
- Valve stem seals? Can these be inspected with cover off and pressing with a small screw driver between springs to see if they are still flexible?
- Compression test, would need to buy one for diesel pressures. Would need to pull all the injectors for tools access point, do I really want to do this (no)? I would do this if I was considering pulling the head to redo the valve guides.
- Reseal the turbo, is this quick, cheap and easy? There is a lot of lateral play (side play) on the turbine, but it was there even before the oil consumption. The turbine doesn't hit the walls though. Turbo type is the one with what looks like a big hose clamp on it so it should be easy to remove?

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1972 450SL
1982 300D Turbo

A compression tester can be bought from harbor freight for around $25. You can test through the injector holes or glow plug holes.

You can check it the next time you change plugs. Remember to get a GP hole reamer to make her happy.

Turbo cartridges are $250. Sounds like you could go with a rebuild kit, though. Considerably cheaper. It bolts on with 4 bolts to the exhaust manifold and 4 bolts to the head down pipe (from what I remember). Real PITA, but not impossible. Need a U-joint for the socket wrench.