Redesigned vacuum pump for the 617?
 

There was a thread started by Ipozzo a few days ago about replacing the vacuum pump on a 1990 w124. I know little to nothing about the w124 chassis, but I gathered from the discussion that at some point on those engines they updated the vacuum pump from a open design that could cause damage when it breaks to a closed design that wouldn't. I'm giving thought to replacing/rebuilding the pump on my 1983 300D soon. Did they ever make any such redesigns for the 617 engine and its pump? What should I be looking for on a replacement pump (other than good quality, presumably a Piersburg)? Or could the closed pump from the 601 be backwards-compatible?

Thanks in advance for any help you can give me.

The pumps in the 617 are fine. Buy Pierburg and call it done. I do believe the 61x pumps are also easily rebuilt

At one time the 617 Vacuum Pump Bearing/Roller on the Pump Arm had an was open and had a Plastic Bearing Cage and when The Cage came apart the Ball Bearings fell out and there could be Engine Damage from the Failure. I think there are also some with exposed Steel Cages but the later ones have a washer on each side of the Bearing.

I think by your year that was changed and there is a Washer on each side of the Bearing.

What can cause a Vacuum Pump Failure even on a new Piston type Vacuum Pump is if the Timer Intermediates Shaft Bearing is worn out and has too much play and in and out end play.

If you do the complete rebuild buying both Kits it will cost more than a new Vacuum Pump and you have no warranty.

There has been one person who changed the Bearing/Roller on the Arm but I cannot remember the Details. And, doing that will not fix a worn Intermediated/Timer Shaft.

Thanks for the info Diesel 911. I have a new pump for mine and plan to install it this fall. I know that play in the area of that intermediate bushing is critical. Do you know how much play is tolerable?

This is what I have in My Notes:
"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."

Maybe simly loosening the Tension on the Timing Chain would work. But, I have never done the job before.
The Picture I barrowed is from one of our Members. So someone has more details on the job then I do.

The job should be done with out the IP fitted and without the timing device fitted - however in the real world I reckon you are best off checking the play as best you can. You know for sure that if you exceed the specifications above you are most certainly going to be out of luck when you strip everything off of it.

More information here =>

http://www.peachparts.com/shopforum/3160038-post35.html

As well as a picture of the slightly different non turbo intermediate shaft configuration

Great info, folks, thank you all. Learning things I never knew about vacuum pumps. It does seem perfectly rebuildable, but since I'm lazy and I like having warranties, I'll probably buy a new one. I suppose buying new parts helps encourage manufacturers to keep producing w123 parts, anyway.

Stretch...wow. Just wow.:notworthy: Now that's what I call a vacuum pump writeup. The world needs you to write a book for w123s like John Muir did for the Volkswagen bus. Anyway, looks like I need to check more stuff while I'm in there. Thanks for the info, my car appreciates it.

i thought 616, 617 pumps could grenade just like any other? mine has exposed bearings...

I would rather someone made a cap to replace the vacuum pump. One could then use an electric vac pump, like come on many newer cars (VW, Volvo) for the brake booster. That would also be an easy fix for a worn vacuum pump cam disk.

I don't think I know that much about them!

What like this?

http://www.peachparts.com/shopforum/...1&d=1402000281

(I got this picture from marktplaats.nl where the OM617 was up for sale - advert is long gone now)