earlier I posted about my 1987 300SLD shooting oil like a geyser from the oil dipstick hole on High RPMs 4000+, and I am still trying to figure out where all the blowby is coming from I did two more compression checks ( using the injector opening as opposed to the glowplug opening from last time). and I only did 10 cranks not 12 cranks like last time.
I did a warm and cold comparison. I let the car cool down overnight and connected a battery charger to make sure it wasn't drained from the previous test.

here are the #s from front to back Warm, 450,425,440,430,430,450
and the Cold cranking 460,410,440,375,375,440
remeber the battery was fully charged on the cold crank so dont be alarmed on the first cylinder actually being higher.

so for a car with about 200,000 miles it seems tight as it can NOT be Rings ??
maybe head gasket, or valve guides..but could they cause Olde faithful from the dipstick hole?

I do notice during strong driving Oil weeping out of the small holes in both the dipstick tube and the Valve cover ( small hole back left side).

I put a crankcase breather on the hose going from the valve cover to the turbo inlet, but still getting oil seepage out of the holes.

I guess its more pressure build up than the small diameter J-shaped tube in the valve cover can handle?

its just a mystery. just scratching my head..and keep adding Oil to replace the oil weeping out. ( and smelling the fumes burning off the hot engine)

maybe replace the 10W40 motor oil with 20W50 will prevent the blowby?
thanks for all your help.
Mark

Can you put a pressure gauge on your additional hose to get a sense of how much pressure is building up? There are a few threads on here about random increases in crankcase pressure which pushes out the dipstick. I can't remember if anyone ever came up with a credible hypothesis to explain it besides a plugged PCV hose.

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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

Check the Crankcase ventilation system first.

The compression readings in Red could indicate that there is a Headgasket issue between 2 cylinders.

If you can use your Compression tester adapter hooked to dry and hopefully filtered compressed Air you can pressurize one of the 2 Cylinders that had the same compression test reading and see if you can hear Air leaking into the other Cylinder.

I have also wondered if it is possible for Exhaust gas to get past a worn Turbocharger Exhaust Turbine Seal. Once past that Seal the Exhaust gas would go down the Turbo Drain Tube and pressurize the Crankcase.

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84 300D, 82 Volvo 244Gl Diesel

I have similar problem with one of my SDL with 344K miles. I put a tighter O-ring in the dip stick to stop the oil from coming out. I also observe blow by smoke from the left back of the valve cover pin hole at idle. The car still drives OK, albeit shakes a bit at idle. I suspect it is the head gasket and I am planning to pull the head when I have time.

Do you notice oil on the cylinder head bolts near #1 and #2 injectors? I clean it a number of times and it seems oil is seeping from below. I would read this thread with keen interest.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

thanks ah-kay,ill have to look at the head bolts and see if i notice any oil.
and D-911 I Agree the matching low pressures are classic head gasket symptoms, and I like the idea to check the Turbocharger Exhaust Turbine seal , but if that fails wouldn't there be an extreme amount of smoke out the exhaust ?
ill have to buy some adapters so I can connect the air compressor to the cylinder compression tester's injector fixture.
I am not sure how to test the Crankcase ventilation system, i have hooked up a small hose to the J shape tube and blown into the valve cove without any resistance.
thanks for all you ideas/ opinions

Just a hypothisis if you are using vegatable oil. For some reason frybird made me suspect it.

At low cranking rpm for compression checking the rings may be able to respond and somewhat function much better than at normal operational revolutions. Thats if they are partially gummed up.

A good soaking might dissolve the goo and gum. Allowing return to normal unhindered movement.

Just a thought.

Do you have access to an air compressor? If so, you might do a leak down test - certainly before pulling anything significant apart.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

I think for the Crankcase Ventilation system you just need to make sure all the passages are open and clean.
I do not know on your Engine but on my 617 it is a passagein the Valve Cover and some hollow tubings going to the Air Filter.

If Oil leaks out into the Turbine Housing there would be smoke.

The Seal is like a Piston Ring and it rides in a groove on the Turbine Wheel. The Ring itself wears and to a much lesser extent the Groove also wears.
Exhaust gas is thinner than Oil so I am speculating that it could more easily get buy the Ring than Oil.

The Oil has more pressure than the Exhaust gas at the Bearing but there is an empty space between the Bearing Journal and the back of the Turbine Shaft.

Oil gets sprayed out of the Bearing Journal (this is part of what cools the Bearing Housing on the Turbine side) but it is hard to say what type of pressure the Oil has when the spray hits that area.

Like I said it is speculation. The only way to prove it would be to replace the Seals and Bearings or get a rebuilt Turbo and see if the Blow-by is reduced or goes away.
Either way is a little expensive just to prove a point.

I would also think any sort of restriction causing Exhaust Back Pressure might make it more possible.

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84 300D, 82 Volvo 244Gl Diesel

I like the Idea of the back pressure, and easy test would be to gauge the crankcase pressure, then pull off the muffler and check the difference.

the valvecover crankvent system is a sealed chamber in the top over the cover with a small j shaped metal tube about 1/4 inch for input, and output is a hose that connects to the turbo air input, which should suck the crank gasses and then mixed with fresh air to be compressed by the turbo into the intake manifold.

has any member dissected the 603 valve cover to see how it works ??

What is your oil level? If it is overfilled, I've heard of oil foaming creating pressure in the crankcase. I don't know how much pressure this can create but just a thought.

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Sam

84 300SD 350K+ miles ( Blue Belle )