Blowby oil in Turbo?

The blowby line running from the valve cover to the intake system (79 SD) seems to put a bit of oil into the turbo. Should this be happening?

[psfred]

Sounds like excessive blowby. You can check by loosening the oil filler cap with the engine running (don't take it completely off -- oil will fly off the cam and go everwhere). If you get big clouds of vapor, you have too much blowby.

This can come from worn rings/liners or from bad valve guide seals/guides. The latter is cheaper to fix than the former.

There will always be some oil in there on an older diesel, as they all have some blowby. Even a brand new rebuild will have a little.

What is your oil consumption like? If you aren't using much, I'd not worry about it. If you are using a quart to a tank of fuel or more, you have a problem.

Peter

Oil consumption is minimal, so far. The head gasket seems to leaking a bit on the passenger side of the engine. But even with that there is very lttle consumption. And the power seems to be quite good. My concern is that the turbo impeller will get caked or have any exposed plastic or rubber eaten up by the oil. But if that was the case then I suppose they wouldn't have designed it this way.

[psfred]

Blowby is nasty -- that is why it is routed to the intake on all diesels. Everything up there is oil resistant.

You won't have oil coking on the impeller unless you really get it too hot and just shut off the car without a cooldown, and even then the damage will likely be in the bearings, not the impeller.

Sounds like the amount of oil you have in the turbo is normal. Get a new grommet, though -- you are sucking unfiltered air into the engine, and this is very bad!

Peter

Is the blowby on later models routed to the air filter cover?

[psfred]

I suspect it is routed to the air intake or manifold, if turbocharged it has to be in front of the turbo (or you will pressurize the crankcase!), na can be into the manifold (like my old 220D) or air cleaner.

MB has used all three at one time or another.

Peter

It is tempting to rerout this blowby to the intake before the air cleaner. My only misgiving is, who am I to second guess the MB brains? Also, I would want to turn the filter about a 1/8 spin every couple thousand miles.

[psfred]

Don't. The filter will fill up with oil and dirt very quickly. The blowby is particulate free and can be burned with no deleterious effects on the engine.

Even on engines with oil bath air filters the blowy is routed directly to the intake or to the front of the intake by the vacuum governor flap (by a vacuum controlled valve).

Peter

[lrg]

In response to psfred and mccan, my '85 turbo vents the blowby to a "Y" fitting. One branch goes to the center (filtered side) of the airfilter and the other to the intake a few inches before the turbo. Why two? Beats me. This is a Calif. car though so it may be some wierd smog issue. It appears most/all of the blowby gets sucked into the intake manifold because the filter end shows no sign of oil. FYI.

[engatwork]

Blowby routing.
On the '83 240D I am rebuilding I put the original configuration back in - that is what I call a "cyclone separator" (don't know the real term) back in. This system separates the oil fumes from the liquid and returns the liquid back to the oil pan. The fumes go into the intake downstream of the filter. I had the option of going with the '80 manifold arrangement which does not run the separator and justs dumps the blowby back into the intake downstream of the air cleaner. I figured I may as well recover as much liquid oil as I can. The '85 300D has the separator in built into the center of the air filter so the vapors go into the air stream after the filter.
I will see how it goes with the 240D, it should be ok because I replaced the "o-rings" on the return line and installed new hoses around the separator but if it makes a mess externally I will go with the 1980 arrangement.

[psfred]

Jim:

The cyclonic separator removes a very large proportion of the oil mist in the blowby and will greatly reduce oil consumption as the engine ages. Well worth the hassle of changing the o-rings.

Peter

[engatwork]

That is exactly what I figured Peter. There are ways to keep it from leaking.

[be459]

The 85 Calif 300D/SD do not have the oil separator. The configuration is exactly as what lrg stated. I found very little oil in the air filter but some oil in the turbo intake housing.

David