Four years ago, I replaced my vacuum diaphragm with a FEBI brand for my 79 240D.

Having problems with no vacuum, so I checked the diaphragm and sure enough, it is ripped.

Is 4 years about right for the life of this rubber item?

I am also wondering if I placed the 2 metal discs the wrong way - they have a curved side vs a flat side.

Attached Thumbnails

 

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

****If by "curved" you mean a rim or a lip then the "flat" side goes against the diaphragm and the lip goes away.***

Ignore this. I'm dealing with a case of the flu and my brain is foggy. Your alignment is correct.

Four years seems to be a short time but a ton of variables can be present. Type, condition, contamination (chemical and metal particles) of the oil can cause premature wear.

I am guessing you are referring to your OM616 powered 240D's vacuum pump?

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Yes, sorry - this is supposed to go in the diesel discussion...

Original thread where I changed the vacuum diaphragm: Is my 204D ready to blow?

Don't know if I can move this or if a mod has to do it.

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

What kind of shape is the rollercoaster cam in? What about the thrust bearing behind it? Linkage/bearing condition? If worn, they can take out the vacuum pump.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Nah, the "Tech" forum is fine.

I notice you refer to yourself as a "Registered Wahine", are ya from the Islands?

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

Rollercoaster cam?
Is that the rod I attach the diaphragm on with the hex screw?

EDIT: researching VACUUM PUMP FAILURE! Are you neglecting yours??

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

OK, well between working on the 300E and the 240D, I am jumping back and forth and getting a master's degree in tinkering.

Yes, hanging my hat here on the Big Island atm.

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

In the photo in the first post, the curved surface is next to the diaphragm and the flat surface was facing away.

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

The rollercoaster cam is the part inside the engine that operates the mechanism in the vacuum pump. If you peek in the hole that the vac pump attaches to, you'll see it on the sprocket that drives the injection pump.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

The discs must be positioned properly as explained and the rod must be fully extended forward when the cover is tightened.

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Tomorrow I will have to take off the pump to get inside:

https://www.youtube.com/watch?v=obCFLey6obo

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Can't do it.
Can't take the pump off to see inside.

More than one hex bolt is getting stripped....
I guess I'm just gonna have to keep some spare diaphragms and see how long they last.

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Very helpful thread - was here also a few years ago...

Vacuum pump diaphragm replacement pix

EDIT: Looks like I had installed the discs incorrectly - the larger one should be closer to the engine.

This is probably why the diaphragm failed so quickly.

We shall see - have a spare diaphragm handy just in case.

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K

Here we are back at the same place again.
Having no vacuum, as the engine will not shut off unless I block the air.
(Even the stop lever will not work.)
So replace the vacuum pump or rebuild?
Is there anyplace that rebuilds these?

__________________
1991 300E 124.030 103.983KE 722358 03 412178
207K

1979 240D 123.123 250K (Project car)

2000 Ford Ranger, 187K

2015 Dodge Ram 1500 EcoDiesel 37K