On my 91 300D, I concluded that my vacuum problem was a bad VCV....so I replaced it. Things were noticeably improved, but I still had the occasional bumpy downshift. So, just for grins, I took the vacuum reservoir offline. And, wadda you know, shifting is perfect.

Especially on a 23 year old car, I'm all for simplifying the vacuum system to the extent possible to eliminate variables. AFAIK W124 vacuum reservoir - purpose?, the only purpose of the reservoir is to create a buffer of vacuum for faster flap openings and closings in the climate control....which I can certainly live without.

Anyone else take their reservoir offline? Any noticeable effects?

I know eventually I can eliminate the BFS....but I think I'll leave well enough alone for now.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Drove around a bunch this morning....vacuum functionality is perfect in all respects....flaps open and close immediately and, for the first time ever, headrests retract immediately.

I wonder if one of the reasons for the reservoir in the original design is the extent of the vacuum network....perhaps not nearly as necessary once the stuff on the passenger side of the engine is eliminated.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Do your door locks work?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Yes....but that's a different system, operated by an electric pump.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I wondered if eliminating the reservoir would slow the "response time" of vacuum to the transmission. But when I checked vacuum to the tranny while cruising around I found the supply to be very responsive to pedal travel without the reservoir. Vacuum climbed and dropped almost instantly, as I assume it should.

Still can't seem to smooth very light "throttle" shifts though...

Adjust your bowden cable.

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Cheers!
Scott McPhee

1987 300D

that problem more sounds like old ATF or bad modulator adjustment.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Thanks for the tip, you were right I had the cable much too loose from seat of the pants adjustments. Disconnecting the ball socket and adjusting correctly helped smooth the low throttle shifts, although now my car is pretty much in 4th from 30mph onward.

1-2 and 2-3 are still pretty harsh, no where near as smooth as a modern automatic unfortunately; but with the fluid fully warmed, not too bad either. I'll keep tweaking I guess.

Just wanted to give credit where it was due, apologies for being dismissive at the time.

Cheers

The vacuum reservoir is a completely passive system. Theres not much that can go wrong other than the rubber hose connectors. I would check those, replace whats worn out and move on. I've eliminated a lot of vacuum hoses and devices in my engine bay but the reservoir in the driver's side fender is still there.

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CENSORED due to not family friendly words

I noticed that MB themselves eliminated the vacuum reservoir effective 06/91 with MY92.....looks like they themselves regarded it as unnecessary when they revamped the vacuum system for 1992.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Driver side?

Don't forget about the coolant overflow tank. The hose to mine was corroded in half... glad I found that one

I wonder if I could fill the reservoir as a little back up supply...

The reservoir acts as a buffer when there's a big demand on vacuum, such as when you pump the brakes. I don't see any reason why it would ever be a problem, but people seem to like removing things.

If it's involved in something as critical as braking (which I'm not sure is the case...isn't that what the brake booster is for?), why did MB eliminate it in 92?

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

The brake booster is just a big surface area movable rubber saucer like thing which responds to vacuum being applied to one side of it which then helps push on the hydraulic piston of your brake system..... it does not produce anything... it is passive.... if you really do not have a container for vacuum then perhaps your electric pump is sufficient... but railroad cars, trucks, all the other cars with any brake boost... which pretty well means ALL those with any disc brakes... due to their lack of self energizing design... have the vacuum saved up for use when needed.

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

MB did not rid of the vacuum reservoir - its installed on my 1995 E300D behind the passenger fender liner and is linked via a brick red vacuum tube that tees off from the Y junction behind the brake booster.

Mine was disconnected because the line was cut, I repaired it with some rubber tubing while I was doing blower motor R&R. It smoothed out the yank of transmission shifting to a firm surge of power and also helped the dashboard flaps to work quicker (I think)

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)