I recently discovered that despite the fact that the engine shuts down fine the shut off diaphragm was leaking oil. It has made me think we should put a clear filter in our brown shut off vacuum lines so that oil leaks into the vacuum system are visible. I had assumed that a diaphragm with a hole in it would manifest with poor/no shutdown so oil leaks would be readily detected. Apparently not so.
I haven't found an appropriate filter to go in the line but I will look for one when I next visit an auto parts store.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Or, you could put the couple dollars a filter would cost towards the cost of a new Vacuum Shutoff.

Does the Vacuum Shutoff hold Vacuum?

__________________
84 300D, 82 Volvo 244Gl Diesel

I'm going to replace the shut off valve. I'm talking about putting filters in that line as a general principle on these vehicles.

When I pulled a vacuum on the shut off valve, it just sucked oil.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

"Hens tooth" 1985 300D vacuum filter dark black
"Hens tooth" 1985 300D vacuum filter dark black





Have a great day

__________________
ASE Master Mechanic
https://whunter.carrd.co/

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

I couldn't find clear small fuel filters at the auto parts store but found a clear 1/4" lawn mower gas filter at the hardware store. With a little dish soap in the hose, I was able to force on a piece of vacuum tubing to each end which will also fit the brown vacuum tubing in the car.
The W116 300SD had no OE vacuum filters that I can see, unless a PO removed them, but the lines look original. Since it has the dual diaphragm vacuum pump with separate lines to the brakes and everything else, a person would also need a filter in the large brake vacuum hose to detect a failure in the pump vacuum diaphragm even if a filter was put in the 'everything else' line.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

There are several threads on installing these clear fuel filters on vacuum lines. I have 3 on mine. Shutoff valve line, transmission line, and cabin vent line (just to reduce possible dust).

I would not put one on the large brake vacuum hose as it would become a restrictor and reduce vacuum to the brake system - not a good thing

__________________
Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html

Roy is correct. Also when the diaphragm fails, the pressure in the crank case forces blow by down the vac lines.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

That doesn't make sense to me. If crankcase blowby is forcing it's way past the vacuum pump diaphragm there wouldn't be any vacuum in the system causing the brake booster to fail and making most people stop driving and fix the pump to get their brakes back.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

He means the shut off diaphragm fails, crankcase blow-by is forcing it's way into the vacuum system.
Even a small rip or puncture will pass a lot of oil.

With the engine running, shutdown:
* Vacuum is applied to the failed shut off diaphragm.
* Crankcase blow-by is forcing it's way into the vacuum system.
* All of the MB vacuum pumps that do not have a second dedicated vent/output hose; air vacuumed from the system is vented into the crankcase, increasing crankcase atmospheric pressure = making the issue worse.

OK. That I get.
I remember reading somewhere that oil would get into the vacuum lines by a failure in a vacuum pump diaphragm and the clear filter would give warning of a failed pump diaphragm. That's the part that doesn't make sense. Seems to me that oil in the vacuum system must be coming from the shut off diaphragm and not a failed vacuum pump diaphragm.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I just finished installing my filters from Phil, one in the brown shut down switch line and one in the door lock and headlight adjustment line. I dont think it would matter which way they go although with the "beveled" end toward the switch it looks like oil would collect on the outside of the filter paper in the event of a ruptured diaphragm, not that you couldn't see it if were on the inside.

__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

We put one on the final car in our fleet that did not have one (my dad's '82 SD).....1.5 months later the shut-off failed, and it now has oil in it. It still shuts the car off, but the filter is half full of oil. The car is sleeping for the winter, so we will change the shut-off (have a new one on the shelf) eventually....

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

I imagine a filter of any type in a vacuum circuit would act as a resevoir and delay or eliminate function of whatever system it was a part of. i.e: slow shutdowns and messed up shift patterns.

__________________
RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

____________________________
FACEBOOK: PANZER450

NO.
It has zero impact on the vacuum system function.
Vacuum reservoirs are a NULL/zero factor to function, they are there to even out high demand that momentarily exceeds vacuum pump supply, and supply vacuum for functions after engine shutdown.


Total volume of the fuel filter is = to a single climate control or door lock vacuum actuator, but with no risk of leak.