Apparently parts are not available though instructions are.

I'm considering looking at this as I need to replace the oil cooler lines also. To work on the vacuum pump, the radiator needs pulling so it might be good to do both at the same time.

I've not worked on an MB vacuum system before at all. Symptoms are: motor slow to turn off sometimes, vacuum locking of doors spotty, power assist not good on brakes.

I have no way of knowing at this point if the lines are bad and the pump good. I somehow suspect the pump needs help. Web-izens report that the pumps on old 617s often get old and fail.

But what do to w/o replacement parts?

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1986 300SDL, 362K
1984 300D, 138K

Rebuild parts are NLA for a 617 vacuum pump. Measure vacuum directly at pump. If insufficient, start looking for replacements. Piersburg was the OE supplier and there used to be pumps under that brand. Those were gone the last time I needed one and ended up buying the best priced pump from MB that I could find.

I have 2 cores on the shelf and still can't come up with a working pumi. It's been a while but "think" it was the internal check valves that caused a problem. The good news is that they don't frequently fail.

Be careful getting the bolts out. Make sure the heads are clean. Spray with Croil. Tap a correct sized, ground-square allen wrench into the head ahd hopefully all bolts will come out without stripping. One of the old style impct wrenches that you hit with a hammer may help.

Use antiseize and new bolts during the install in any of the bolt heads are the slightest deformed.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

I don't remember having to remove the radiator to get the vacuum pump out. Someone else will have to verify if that is so.

MY Question on Timing Chain Failure
Who has or knows someone that has experienced a timing chain breakage/failure? - PeachParts Mercedes-Benz Forum

My question What in particular causes vacuum pump failure?
http://www.peachparts.com/shopforum/diesel-discussion/204187-what-particular-causes-vacuum-pump-failure.html

In and out play of used Fuel Injection pump timer
http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1499425-took-off-timing-device-questions-about.html
Timer End Play
I went back and took a closer look at both the CD and book Service Manuals and found it listed as: End plan of intermediate sprocket shaft: 0.05-0.12mm.
In section 07.1-240 of the Service Manual.
I assume this measurement is take with the Timer installed on the Shaft and with no Timing Chain on it to interfere with the measurement.
Repeat broke new vacuum pump
second vacuum pump, help! on a trip-Toronto - PeachParts Mercedes-Benz Forum

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84 300D, 82 Volvo 244Gl Diesel

Probably the best post on the subject....
http://www.peachparts.com/shopforum/diesel-discussion/339870-more-than-you-likely-ever-want-know-about-om61x-piston-vacuum-pumps.html

^ I'll study that, looks useful.

I seem to recall one of the internet Benz gurus mentioned removing the radiator. But now upon looking closer I see that removing the radiator does not necessarily mean removing the oil cooling radiator so pernaps my notion about doing the two jobs jointly is not necesarry.

OTOH, looking at it, sure looks like having the radiator out of the way would make that job easier.

As for pump parts for rebuilding, a new one for $350 is not an extremely high hurdle. I'll test mine and if it's bad will likely buy a new one. Rebuilding the piston variety looks more difficult than with the older diaphram units.

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1986 300SDL, 362K
1984 300D, 138K

Is there any chance that your vacuum issue is being caused by the Check Valve that screws into the vacuum pump housing. New they are around $75 now. What happens is the parts fall out of it (not to worry the parts don't make it to the inside of the vacuum pump).
Not hard to get at and just unscrew it and look inside.

For myself I don't know if the older diaphragm type vacuum pumps are a direct swap. There is some difference between the why the oil comes out of the intermediate shaft to lube the Vacuum Pump. I also don't know if that makes any difference.

Concerning the rebuilding the piston end kit sometimes comes up on eBay and also the actuating arm setup. But, if you buy both it costs more then a new vacuum pump.

Some have said you can change the bearing/s on the actuating arm if it is good and re-use it I have not read in detail on that.

The advantage of getting a new Vacuum Pump depending on who you get it from is a warranty and you get a new check valve as mentioned a $75 value.

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84 300D, 82 Volvo 244Gl Diesel