I have a 85 300D with about 450,000-500,000 km on it. I've been reading through a lot of posts with the vacuum pumps and I was just wondering if I should do a full overhaul even tho it's not required?

Do you high mileage W123 owners replace the vacuum pump as a precaution? I don't want mine to go kaboom one day and mess up my chain etc. What's your replacement recommendation if your timing chain has minimal play?

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1976 Mercedes 240D (Sold)
1985 Mercedes 300D Turbo Diesel: 500,000KM
1986 Mercedes 300E (Sold)
1988 Mercedes 300E (Sold)
2002 Mercedes C240 (Sold)
2008 Mercedes C350 4matic

A great site for purchasing industrial rubber products!

Industrial Rubber

I don't have my notes here but you should go to the repair links.

You could pull off the Vacuum Pump and check and see if your pump has the unshielded bearing; you will be able to see the balls and the bearing cage. Especially if the cage is plastic replace that bearing.

In the repair links you will find that if the timer shaft bushing has too much end play it can destroy even a new Vacuum Pump.

Concerning doing a complete rebuild. There is 2 kits. One for the Piston and one that has a replacement arm and bearing assembly. If you could find both kits they would cost you more then a new Vacuum Pump (which used to be made in Spain) and if you rebuild it yourself you will halve no warranty.

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84 300D, 82 Volvo 244Gl Diesel

There is pics of the old and new style of bearing arrangement:
https://www.benzworld.org/forums/w124-e-ce-d-td-class/1655942-1987-300d-what-look-2.html


If your 85 has the original vacuum pump it should be the later version without the exposed balls and cage.

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84 300D, 82 Volvo 244Gl Diesel

As a routine maintenance item, every 200,000 miles, I replace the vacuum pump. I do not believe kits to rebuild the pump are available any longer. I have seen firsthand what an exploded vacuum pump can do to an engine.

The bearings on the piston pumps can fail and when they do they can make a mess of the place

Blindly replacing the pump isn't necessarily going to help - a co-conspirator is the intermediate shaft bushing: Play in the intermediate shaft allows too much longitudinal movement which exaggerates the "roller coaster" effect of the piston pump bearings rolling over the timing device's track

I did a rather silly involved thread on the piston pump a few years back =>

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

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Yes, pump and gasket. Every 125,000 mi/202,000 km.
My situation: Maintaining two 617.952 engines since early 1990s.
Approximately 455,000 mi/733,000 km.

Rebuilt Pump around $350

https://www.pelicanparts.com/More_Info/000230136580.htm?pn=000-230-13-65-80-MBZ&gclid=CJ-qz-L41-ICFdggrQYdk5QHZA

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84 300D, 82 Volvo 244Gl Diesel

This appears to be a new genuine Mercedes vacuum pump.

That was all that was available the last time I looked. There used to be Piersburg pumps but no more. Stock of MBZ pumps is dwindling. Kits to do a complete rebuild weren't available and the kits to do a partial rebuild were more expensive than buying the pump. Check valves were the problem on mine and I didn't find the valves - but saved my old pump in case. I also did not find a significantly lower price.

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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.

The price on the Check Valve that screws into the Vacuum Pump Body has risen to about $50.
From the pics I have seen of rebuilt and new vacuum pumps they come with a new Check Valve.

I did find the Piston end kits on eBay for about $170 each and the complete arm assemblies for about $350. So if you add those 2 together you have $520 (there is also going to be added shipping charges.) and you won't have a new check valve unless you purchase that separately for another $50. And when you are done rebuilding it yourself no warranty!

To me that makes the do-it-yourself rebuild not cost effective and you end up without a warranty.

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84 300D, 82 Volvo 244Gl Diesel

the check valve was 80.- when I bought one in the fall of 2017

I forgot to post these
2 Vacuum Pumps destroyed timer Bushing Identified as the problem
http://www.mbca.org/forum/2013-12-29/why-are-these-vacuum-pumps-being-destroyed

2 Vacuum Pumps destroyed timer Bushing Identified as the problem
http://www.mbca.org/forum/2013-12-29/why-are-these-vacuum-pumps-being-destroyed


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



When you hear an odd noise up front check the vacuum pump first by listening with a Mechanics Stethoscope or some substitute to see where the noise is coming from.
Tapping sound caused by Ball Bearings falling out of Vacuum Pump
http://www.peachparts.com/shopforum/diesel-discussion/340095-vacuum-pump-ball-bearings-fell-out-now-what.html

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84 300D, 82 Volvo 244Gl Diesel