I've been wondering; where does the vacuum pump intake it's air? I've always wondered if there is a filter some where that may need to be cleaned or replaced.

The Vacuum pump pulls air from the vacuum lines to create the vacuum.DUH!
Sorry I couldn't resist. Jeff

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99 NU-WA Snowbird 34+2 SE 102 5er
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Yes, but.....

All those lines are (supposed to be) sealed. Is there some kind of relief valve to allow air in so that the vacuum doesn't build to a point that the vacuum components don't operate correctly?

Drinkit,

The maximum amount of vacuum you can have is about 15 PSI. Notice this is exactly the same as air pressure at sea level.

Vacuum is just the pressure of the air acting on the opposite side of the diaphram that vacuum is applied to. If there are no leaks, there is no air flow.

P E H

Where does it send the air it pulls out of the system? I don't see a vent or port. Does it go into the timing chain cover?

Sixto
91 300SE
87 300SDL
83 300SD

Sixto,

The vacuum pumps on some models have a hose going into the engine air intake system.

P E H

That hose is the "exhaust" for the vacuum pump. It is a good idea to check that hose every so often. On the older MB's with a replaceble disc in the vacuum pump, when the disc tears the hose to the intake will darken as it fills up with oil. The oil will also fill your vacuum lines all over the place.

Seems like the maximum vacuum would be zero PSI, which is the stuff outer space is made of.

Drinkit,

Yes vacuum would be Zero in outer space but zero is a minimum, not a maxium. Since we are on earth where the atmospheric pressure is approximately 15 PSI or 1 Bar at sea level the maximum vacuum would be 15 PSI or 1 Bar.

It should be intuitively obvious that a vacuum pump would not work in outer space. I hope you don't have to ask why.

P E H

Isn't that when you use PSIG vs PSIA?

Sixto
91 300SE
87 300SDL
83 300SD

Vacuum pressure is really atmospheric pressure pushing on the opposite side of the diaphram that you apply the vacuum to. That's why it is limited to a pressure of 15 PSI or 1 Bar. If the area of the diaphram is 1 square inch the maximum force that could be exerted by the diaphram is 15 pounds. If the diaphram is 2 square inches, the force exerted would be 30 pounds, ETC.

Unlike air or hydraulic systems no pressure release is needed in vacuum systems because atmospheric pressure is the limiting factor.

P E H