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1991 350SD - Need help with vacuum pump and IP leaking

1K views 4 replies 2 participants last post by  50$84sd 
#1 ·
I have a 1991 350SD w/ 200K miles. Vacuum pump works, but the output is only 18 psi. As far as I know this pump was designed to output 23psi.

Does it mean that with age they produce less vacuum, and that's OK. Or does it mean that it's about to blow up and I should replace it asap?


Next, it seems that my IP leaks a lot of fluid (I would guess oil, based on how it looks and feels). The head is clean, the block is clean, but the bottom of the IP is all black and wet. Where ever it's coming from leaks down the side of the block under the IP, collects in small pools of oil in every available cavity and produces a nice size black stain under the car.

So, can the bottom plate of the IP leak? If so, would it leak diesel or oil? Where in that area can oil be coming from?

Related question, how hard would it be to R&R IP in order to replace gaskets (if that's where the problem is)?


Thanks for your help,

Vlad
 
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#4 ·
Vacuum pump I will replace, since it's better to be safe than sorry.

Leaking oil is the bottom cover of the I/P. A well known problem. Here's a great link describing how to remove the pump: 603 Injection Pump removal with pictures - PeachParts Mercedes ShopForum

During the removal, the vacuum pump must be removed, and thus it will be replaced.

Sounds like it's a 2 hour job for someone with skills or a 4 hour job for me. Still not bad. Just need to get all of the o-rings, gaskets, specialty tools, etc. before I start.
 
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