Has anyone tried adding an electric vacuum pump to one of these MB diesels to prevent oil leaks?

I was looking around and found several GM cars from the early 80's had 12 volt vacuum pumps. They are cheap in the junkyards.

The idea is to hook the pump up to the breather vent in the valve cover. On the MB turbos, a tube presently goes to the turbine intake from that vent.

Seems like you could increase the suction on that vent with an electric vacuum pump, and various engine seals would be a lot less likely to leak oil, especially at high speeds when there is more blow-by pressure in crankcase.

Anyone ever hear of this or try it?

Gregory

What do you do with the other end of the pump?

Sixto

Run the other side to the same place, the hole in the turbo intake boot.

Most of my oil leaks have been due to the natural deteriation of rubber o-rings, such as the turbo drain, and vibration, such as the oil filter mount and oil pan. I don't see how a vacuum pump would help for this.

Is this something they used instead of a PCV valve?

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Sam

84 300SD 350K+ miles ( Blue Belle )

The vacuum pump already pumps as much as it can at a given altitude. Adding an electric pump would only increase it's pumping capacity.

Also remember that the tranny is tuned to the stock pump's specific output. Changing that will mess with the shifting.

Its not a PCV valve, its just a 90 degree elbow that goes into the valve cover. A plastic tube goes from that elbow to a hole in the turbo intake boot.

This idea has nothing to do with the stock vacuum pump. It has nothing to do with the tranny.

The point is to evacuate the pressure out of the crankcase, so oil doesn't puke past the seals from pressure in thwe crankcase.

Does anyone have more oil leaking at high speed, vs sedate town driving?

I understand the theory, it's just that I can't see how it would create any less pressure in the crankcase than the existing system. Unlike a PCV system with a small valve, ours uses a cyclonic separator that is pretty wide open. The opening is as large as that elbow that extends into the air intake inside the filter housing.

Unless this system is bypassed, in some way, to impede the normal flow, I couldn't see how an extra vacuum pump would change things for you. Dried out and dirty seals will still leak until you change them. Sure you can try the pump and it might slow the process down some but doubt if it will solve the problem.

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Sam

84 300SD 350K+ miles ( Blue Belle )

Actually, he's not talking about augmenting the existing vacuum pump. He wants to depressurize the crankcase to keep oil from seeping out. Probably would work as long as it is regulated so that it can't damage anything. My preference is to just fix the damn leaks though. A vacuum pump for the crankcase is just a bandaid.

Wes

You won't have a PCV valve on any diesel, as they don't use throttle plates to control the engine speed, and thus don't generate vacuum in the intake.

The job of the PCV valve is to restrict flow under high vacuum conditions (closed throttle). Carbureted vehicles depend on it to achieve a proper mixture under high vacuum conditions. Fuel-injected vehicles may lack this part.

As for evacuating the crankcase, a much better approach would be to fix the leaks the old-fashioned way. What if you started drawing a whole lot of oil mist through the pump into the intake?

I tried one simple thing, it seems to help. Where the breather tube goes into the turbo intake boot, there is an extended rubber sleeve that the breather tube is inserted into.

I put a ty-wrap around that sleeve to cinch and seal the breather tube in place. If there was any suction leakage at that point, its sealed now.

So now there should be marginally more vacuum sucking pressure out of the crankcase.