Vacuum Pump - Oil Consumption?

[DieselPaul]

My dad has noticed lately that his 92 300D has been using oil recently. Like a quart a week. The car does not smoke visibly. I was skeptical of his turbo as there was some slight left to right shaft play when I did the waste-gate actuator swap. However I have not had a chance to look at it yet (he lives in a different city) but he called the other day and said he didn't have brake booster assist and the car would not shut off with the key.

Can the vacuum pump diaphragm going bad consume oil on an OM602?

(I realize on a diesel there is no manifold vacuum)

[jt20]

Consume? -no.

no vacuum system exhaust goes directly to cylinders. The exhaust from the pump does add to crankcase air volume though - otherwise perceived as 'blowby' when you take the 730 cap off.


Not sure if it could pump it to a different location though if the right valve failed.

[DieselPaul]

Originally Posted by jt20

Not sure if it could pump it to a different location though if the right valve failed.

This what I was asking.

I don't believe there is a diaphragm in the 602 pump, I believe its a piston style. Either way, they don't use oil.

This was my answer.

[dude99]

I don't believe there is a diaphragm in the 602 pump, I believe its a piston style. Either way, they don't use oil. Its a coincidence that the pump went out at the same time. If its the original pump he should stop driving it. There is a good chance the pump has\could grenade and take out the timing chain.

[Mxfrank]

First of all, I wouldnt assume a bad pump, a vacuum leak is more likely. If the pump was gone, you'd probably hear the shrapnel rattling around the timing case.

Not only should there be no detectible blowby, there will be a slight vacuum in the crankcase under most operating conditions.

Especially with the turbo, its important to be sure that the engine is well sealed. If you have a leaky pan gasket, valve cover gasket, vent grommet, front or rear mail seal, oil cap, or dipstick o ring, the turbo will draw air and oil right out of the engine. (Again, you will have vacuum, not blowby in a well running motor)

[Mark DiSilvestro]

Originally Posted by Mxfrank

First of all, I wouldnt assume a bad pump, a vacuum leak is more likely. If the pump was gone, you'd probably hear the shrapnel rattling around the timing case.

Not only should there be no detectible blowby, there will be a slight vacuum in the crankcase under most operating conditions.

Especially with the turbo, its important to be sure that the engine is well sealed. If you have a leaky pan gasket, valve cover gasket, vent grommet, front or rear mail seal, oil cap, or dipstick o ring, the turbo will draw air and oil right out of the engine. (Again, you will have vacuum, not blowby in a well running motor)

Note: On my '84 TD, when the vacuum pump's cam-bearing failed, I heard no unusual noises - even after I reached my destination and discovered I had no power-brake and the engine wouldn't shut off. If I had driven it much further, the bearing-lever would have disintegrated. Then I probably would've heard something as my timing-chain self-destructed!

Happy Motoring, Mark

[dude99]

I don't think I've ever seen a Mercedes diesel with a vacuum in the crank case. There will always be blowby.

[Mxfrank]

Originally Posted by dude99

I don't think I've ever seen a Mercedes diesel with a vacuum in the crank case. There will always be blowby.

Definitely a vacuum in any turbo engine. Maybe different in NA engines due to the config of the breather, but I've got to think it's the same off-idle. Vacuum aside, If you have an opening anywhere in the engine envelope, it's a direct path between the intake and atmosphere via the breather tube.

[DieselPaul]

There are those inline fuel looking filters in the vacuum system. I thought it was possible at least on a W123 for engine oil to wind up in the vacuum system.

As I stated in the original post I realize the engine itself isn't consuming the oil i.e. burning it. I didn't know if the pump could suck oil into the vacuum system.

I've sort of gotten my answer. Thanks for your help.

[dude99]

As a side note, the little filters you see in the w123 system (and others) are to prevent oil from being sucked through the system if the diaphragm in the shut off actuator fails.