Tim:

Here's the skinny on the vac pump: you have the later model piston type, vents the air from vac system into the crankcase, so no oil to the intake under any circumstances. No joy, no cheap fix....

Took a while to find that, there isn't a section in the manual for the vac pump.

I did find something else of interest, though (and should have thought of it before) -- does your EGR work properly? If not, especially if it leaks or sticks open at full throttle, you will get LOTS of inky black smoke. Will also cause rough idle and lack of throttle response, too.

I've never heard of anyone screwing up a compression test and getting HIGH numbers.....!

You also may want to pop the valve cover off and check to make sure the oil baffle up there is OK -- if it is damaged or missing, both oil splatter from the cam and oil mist from blowby will get sucked directly down the intake. The baffle knocks the vast majority of the oil out of the air flow.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter

Thanks for the info on my VP, I didn't know how it vented but I was pretty sure it wasn't going the intake. Bummer.

The EGR valve has been disabled per an outing with Ridge of Superdiesel fame. The butterfly valve in the intake has been removed also. Ridge thought the EGR valve could be the problem on my burning oil so I disabled it per his instructions. Alsa, the oil burning stayed. No noticable change in how the engine runs pre or post egr operation, still runs and idles fine, just burns oil.

I'm thinking maybe the oil separator may be allowing oil into the intake. I'm going to check on this. Can oil separators break?

I'll also pull the valve cover to check on the baffle, where is it? Is it easily identifyable? While the cover is off, is it possible to do a simple check on the valve seals?

Tim

Tim:

The baffle is, I think, a pipe like thing in the top of the valve cover. Makes the blowby go 'round the corner, dropping most of the oil out.

If you have a big vac leak, you are blowing extra air through the engine, as the vac pump vents into the crankcase.

Valve guide seals are buried under the springs, no way to check them without taking the rocker arms and spring retainer off.

The butterfly valve has nothing to do with running, it is the anti-back running device -- closes off if the engine runs backwards and shuts it down. Put it back in, the engine CAN run backwards (for a while, no oil circulation). Not usually a problem with the automatic, but with a manual, stalling it can make it start up rotating the wrong way -- quite a shock when you step on the throttle and let the clutch out and the car goes backwards rather than forward in first gear.....!

I wonder if you don't have a substantial vac leak and are blowing oil down the intake at high engine speed. That and excessive blowby are the only things I can think of that would cause your oil comsumption. I'll check with Hans anyway tomorrow.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Peter,

With this newer VP (no vent to the intake) how can I tell if the VP is leaking enough to have that kind of blowing oil down the intake. The brakes and locks work fine. Also with excessive blowby it seems I'm getting back to bad rings or valves, which seem to be fine with good compression in the engine. What do you think of my broken oil seperator theory? The puzzling quest continues!!

Tim

Broken oil separator can make a big difference. They are very efficient are removing the oil from the vapor stream.

What bothers me is the blue smoke at wide ope throttle. Leaking valve seals usually mean oil smoke at idle or after sitting, when there is some vac in the intake. Of course, you don't have a turbo, so you get more vac at speed.

You can check for leaking valve guides by lifting the valve cover at idle -- not too far, or you will get a bath in filthy oil! -- and watching for puffs of vapor from the exhaust valves. If you get much, the seals at least are shot, if not the guides themselves.

One difficulty with these cars is getting proper valve work done -- if the shop isn't familiar with Benz diesels, they will put cheaper steel exhaust valve guides in. These won't expand fast enough (the bronze factory guides expand more) -- the exhaust valves have sodium in the stem to transfer more heat to the head.

Additionally, most shops want to ream the guides to "typical" american "standard" clearance (1-3 thousandth of an inch) which is much to large for a benz valve guide -- the seal won't be able to prevent oil loss. Happens all the time, my brother barely managed to keep the shop from reaming his by taking the head home and installing the valves himself -- they shop (a good one, too!) was all ready to ream them to 0.005" clearance -- this is far beyond MB wear limit!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!