I don't know or have read of a reliable way of to remove the Plastic Main Vacuum Line and get it back on.
I suppose if you heated it with something like a Heat Gun that would stretch it enough for the line to be pulled off but I don't know of a way to shrink it back after your re-install it.
It might be possible degrease the Metal Barb and ID of the Hose with Brake Cleaner and coat the Barb with Silicon Sealant and let that cure. That would likely seal and glue the expanded Plastic Line back in place.

I cut the Plastic Hose off of the Main Vacuum Line and replaced it with Rubber Vacuum/Emission Hose. That allowed Me to make the line Longer and route it over the Top of the Fender Well where it is out of they way. That and the fact that the line is Rubber decreases the chance of snapping off one of the Small Plastic Nipples.

Once you have the Rubber Hose it is easier to hook up a Fitting for Diagnostic purposes.
I also replaced the Plastic Fuel Lines at the Fuel Injection Pump with Rubber Hose.

OK, this is my issue, no vacuum, no breaks, no shut off.

Do I want a used one or rebuild my 294K pump? I don't really need a pump that will last another 30+ years, do I? What if I rebuild it & I mess it up?
What are your experiences?

Thanks,
Dave

Answer
 

I would open it up, verify there is no damage, then rebuild.
As you will see from the following threads, it is not a difficult job.

http://www.peachparts.com/shopforum/diesel-discussion/229331-vacuum-pump-rebuild-thread.html#post1927867

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I would first remove/un-screw the Check Valve that is right under where the Main Vacuum Line screws into the Vacuum Pump and inspect it first. You don't need to remove the Vacuum Pump to do that.

When I had a sticking Check Valve I did not loose all of the Vacuum and it was fixed by hosing out the valve with WD-40 (don't use Brake Cleaner as there is plastic inside).
Others have had all of the parts in that check valve fall out and the Valve needs to be replaced.

Since you mentioned 30 Year + Pump I am guessing you have something close to My Year and Model;1984 300D.
As Hunter said take it apart and see if you can find a cause of the failure.

On the Piston Type Vacuum Pumps the Rebuild kits have gotten really expensive. If you want to replace the Piston Parts and the parts that face the Engine; the Arm and Bearing that will cost more then a whole new Vacuum Pump and if you do the rebuild yourself you have no warranty.

If you have an earlier diaphragm type Pumpe the Diaphram is cheap to fix. I guess the Arm and Bearing end is still expensive but you need to decide since if you did both the diaphragm is cheap.

A used Vacuum Pump would be an alternative.

Stretch also have some vacuum pump threads. In the one thread the Vacuum Pump innards are coated with thick sooty Oil. It could be a good cleaing of the inside parts would restore it till it gets sooty again.

Forgot to add this. This pic shows the part that wears out and can kill even a new Vacuum Pump.

Request
 

Can you add the part number?

Thank you

For my year and model Pelican parts has it.

Injection Pump Intermediate Shaft Bearing
Part#: 617-052-01-06-MBZ

The part number would be: 617-052-01-06

See the attached picture. I only knew Pelican had the number from a search several years ago. On some Mercedes parts it is hard to nail down the name of the part.

There is a steel thrust washer thar rides against the bearing. When I looked that up, I found no part number for it. But on mine it looks like you can simply use the unworn side of the washer against the bearing.

Sadly, for over 2 years my engine has been apart. Not had the interest to get it back together, especially after I busted the windshield.

Back to the bearing I bought on off of ebay and it was $44 like 2 years ago. So if Pelican stocks it that is a fair price. I was from someone in Greece. It did not arrive way past when it was supposed to, and eBay refunded the cost. like 3 months later it showed up so I ended up with a free one.

Cool
 

Thank you.