Vacuum pump overhaul - PeachParts Mercedes-Benz Forum

karmabitch · #1 08-19-2008, 01:44 AM

I need to see and or learn how to replace seals and Valve on a vacuum pump.
123 chassis,i couldnt find such article here,maybe somebody has a pictorial somewhere??

tangofox007 · #2 08-19-2008, 08:20 AM

Piston pump or diaphragm pump? Not all W123's have the same pump.

75Sv1 · #3 08-19-2008, 09:32 AM

Don't know if this link still works:
http://business.baylor.edu/Richard_Easley//autofaqs/Vacuum%20Pump/Rebuild_vac_pump.htm
I tried it, but had problems. I think the rebuild is on the MB CD.
Tom

kerry · #4 08-19-2008, 10:47 AM

On the earlier pump that vents to the air cleaner you simply remove the front cover on the pump with the pump still on the engine and you can then replace the diaphragm and check valves. Only need to remove the fan shroud for access. Pretty simple job.

karmabitch · #5 08-19-2008, 11:39 AM

cani use an old but good seal and check valves from a good working pump i salvaged? i tried swapping whole pumps but the allen bolts started to strip and one was even loose(maybe this the cause of my vacuum failure?)

Stevo · #6 08-19-2008, 01:33 PM

It would help if you ID'd your car in your signature.

Diesel911 · #7 08-19-2008, 02:02 PM

Since Vacuum Pump Drive arm/bearing sometime fails and falls into the timing chain causing the timing chain to break and can result in serious engine damage; I would pull the whole pump off and do a complete inspection.
Also when I took apart mine (a piston type pump) I found that the screws that held the cover on were corroded stuck and even with heat and penetrating oil I broke 2. There is no way I could have removed them with the pump on the engine.

Stevo · #8 08-19-2008, 06:38 PM

Another good reason to pull the pump would be to check the lateral play of the timing device, too much will trash the pump, not sure but maybe around 1mm max.

karmabitch · #9 08-27-2008, 10:55 PM

1980 300d
Is there a way to test the arm once i have the pump out? are the bearings loose on the arm,i could have sworn i saw bearings fall out when i opened the pump?

Diesel911 · #10 08-28-2008, 12:29 AM

Quote:

Originally Posted by karma*****

1980 300d
Is there a way to test the arm once i have the pump out? are the bearings loose on the arm,i could have sworn i saw bearings fall out when i opened the pump?

I have only ever seen the inside of a Piston type Vacuum Pump. The shaft that the bearing rides on is only held by snap rings. Without distorting it remove one of the snap rings and slide the shaft out. This will allow the bering to com out for inspection.
The newer bearings may be shielded and there is no way for the Balls to fall out. On the older one you may be able to see if there are missing Balls.

The rest of the inspection is visual. Look for areas that are worn or parts of the housing that might have hair line cracks.

Also you said you had another pump. Compare the 2 bearings and see if they have the same amount of play.

Bens lover · #11 08-28-2008, 04:59 PM

Quote:

Originally Posted by 75Sv1

Don't know if this link still works:
http://business.baylor.edu/Richard_Easley//autofaqs/Vacuum%20Pump/Rebuild_vac_pump.htm
I tried it, but had problems. I think the rebuild is on the MB CD.
Tom

Sorry Tom but your link is dead in the water...

crashone · #12 08-29-2008, 12:53 AM

"diymbrepair.com/easley/Rebuild_vac_pump.htm"

If anyone can find this iformation it is worth it.

I don't know what to that site but the directions were great. There is a board you can build from plywood to help with the rebuild. You bolt the vacuum pump down but I don't remember exactly, I have slept since I did this. The job is fairly easy, do a search for vaccum pump rebuild etc. There is a lot of information here. Get a new gasket when you get the kit. When you reassemble use some oil inside the piston sleeve to help get it started.