85 300D questions continue- vacuum - PeachParts Mercedes-Benz Forum

meltedpanda · #1 03-14-2008, 10:24 AM

Where is the vacuum pump located? I have no vaccuum at the door locks, and she is shifting poorly and wont shut off. Need to start working on the vacuum system diagnosis but not sure where to start, have downloaded diagrams but all look like spaggetti to me
Suggestions. I have done my search here, but there are so many varriants I am confused

Cr from Texas · #2 03-14-2008, 10:30 AM

It should be on the driver side near the front of the engine. Does not have a belt, it is run off a lobe on the engine and bolts directly.

Start at something you can identify like the brake booster. It should have a line direct to the pump. A T in that line supplies vacuum to the rest of the components. Be careful - there are designed restrictions in some of the fittings and lines. Identify something and follow the diagram to the next branch. Be sure you have the right diagram!

Jordan G · #3 03-14-2008, 10:39 AM

Yah - that's what I was going to say. Follow the main branch on the brake booster to the other end, it's your yellow brick road.

Speaking of yellow - I think that's the door lock colors? I'd start by plugging the door lock branch with a golf tee in the engine bay and see what happens. Many of your problems may go away (mine did - until I tracked the specific leak with my mitivac to the trunk lines).

rrgrassi · #4 03-14-2008, 04:11 PM

Do not forget the green HVAC vacuum lines. They are known leakers as well.