I have two new style vacuum pumps, the one that goes on the motor. One has 94 T300 stamped on it and on that one the rollers are bigger that the other one. The other one has 95 T250 stamped on it and has smaller roller than the first one. They are both Pierburg, what is the difference?

1) Pictures help.

2) Context helps even more. What engine?

Sixto
87 300D

See how the first one is bigger, the bearings are closed on both of them. They both have the screws on the cover.

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They both have the screws on the cover.


HMMMM....that sounds like a 60x type engine?

Sixto, this is your territory.


Charlie

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How much ?

This isn't the first old style pump with screws on the cover I've heard of so screws on the cover aren't definitive of a new style pump but no screws on the cover is an old style pump.

The rollers are the same size. They have to be since they use the same ramp on the IP timer. The old style has bigger bearings with the balls open to the engine. The new style has smaller bearings with the balls shielded, at least until it explodes

The first picture isn't clear enough to see the balls but I expect it looks like this -





Sixto
87 300D

No, the bearings are covered, maybe very early new style.

I would appreciate a close up picture for gsxr's archives.

Sixto
87 300D

I just put that pump in my 92 300D, I took a few pictures before I put it in. I will post what I have. The old pump I took out of my 92 300D had 300,000 miles on it and the plastic bearing cage is still there.

This is the best picture of the pump I just put in my 92 300D, see how the bearings are covered? I like this pump better than the other new style one I have, It just looks stronger.

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The second type is the one you want. The bearings balls cannot come out of the second type, shown below.

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Dave
Boise, ID
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My '95 E300D came with a 94T340 and my '96 E300D came with a 95T250, both Pierburg with MB logo and part number. Both have screws on the front cover and a sealed bearing as in 04Diesel's second picture. As Sixto notes, the roller on the bearing has to be the same diameter for the vacuum pump to work correctly.

OTOH, the two "arms" that hold the bearing shaft can be different size. Several "late" vacuum pumps I have handled have larger or smaller "arms." It is possible that the larger arms are made of cheaper, weaker steel. Larger may not be better -- the quality of the steel is important too and we have no way to judge that.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Well, I put the bigger pump in, we will see how it holds up. The other pump is going in my 84 190D 2.2.

Not intending to go off topic, but are there other threads about re-building, ie, installing new seals and valves, a vacuum pump for a 617 engine ('82 300D-T)? I might be replacing the gasket on my vacuum pump, and this would probably be a good time to do it.

Any advise, pitfalls to beware of?

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Marshall Welch
Seattle, WA
1982 300D-T