My transmission is jerky when shifting gears. I checked that there is vacuum to the flying saucer but none coming out of it. i don't know what the device does. could I bypass the flying saucer altogether? is that a bad idea?

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Ben
1987 190d 2.5Turbo

My saucer was leaking so I followed the vacuum diagram for the <84 model. Seems to work OK.

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1985 300D
The rest:
1957 MGA (comatose)
1965 Falcon (sleeping)
1966 E-100 (rust test in progress)
1976 Ford 3400 D Tractor (workhorse)
1978 Mercury Zephyer (5L playtoy)
1995 Isuzu NPR D (fetcher)
1998 Subaru Legacy (Spare)
2000 Toyota Sienna (School bus)
2008 Toyota Prius (Commuter)

I thought that was a vacuum amplifier.

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Satan creates nothing: he only ruins everything. He does not invent: he tampers. And his followers are no different ~ Archbishop Carlo Maria Viganò

The BUFO amplifies the vacuum signal from the VCV, and modifies it for turbo boost.

On top, there are two connections. The one near the center is full vacuum. The one on the outside goes to the transmission modulator.

On the bottom, there are also two connections. The one on the inside branches off the turbo boost feed near the alda. The one on the outside is the modulated feed from the vcv. If there's a leak in that line, you will have no vacuum output.

As far as taking it out, what, me worry?

so joking aside, are you saying it is ok to bypass?

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Ben
1987 190d 2.5Turbo

what is the official part name for it? I will just buy one on pp

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Ben
1987 190d 2.5Turbo

1233001133

Be sitting down when you look at the price.

I'd much rather revert it to the older system.

-Rog

It's called a vacuum amplifier or vacuum transducer. From what I've read it's not available from the dealer any more. Some used on ebay. Good post here that will answer a lot of your questions:

vacuum amplifer - Mercedes-Benz Forum

You can bypass it, but don't expect great shifting as a result. The OM60x engines use a VCV that is basically either "on" or "off", it isn't a progressive vacuum output. The blue UFO takes the vacuum signal from the VCV and sums it with the boost signal from the intake manifold to decide on the quantity of vacuum sent to the transmission modulator.

Your boost lines need to be hooked up and the vacuum lines all correctly routed. Find out why you don't have a vacuum signal coming out or if the lines to/from the blue UFO are misrouted. If you finally determine that the vacuum amp is bad, source a used one.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

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

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

The VCV does create a progressive signal. What you want to do is tee off the VCV line at the BUFO and measure vacuum. It should be a bit less than system vacuum at idle. As the accelerator pedal is depressed, the vacuum should approach zero. The typical range is 12in-0in.

The 60x VCV isn't progressive in the sense of supplying a varying vacuum signal. It is "on" until the throttle reaches a certain position, then a rubber seal is pressed against the vacuum orifice by a spring. At WOT, the spring is fully collapsed and forced against the orifice for a positive "off". There are several writeups, including on this forum, of how the VCV works and how the vacuum signal is generated. On the turbo engines, the BUFO is there to create a vacuum signal based on engine load, not throttle position.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

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

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

When you measured the vacuum out was that a direct connection to just a vacuum gage or did you tee into the tube going to the transmission? If the later, it could be that the modulator on the tranny is leaking.

My 1985 CA 300D has the blue saucer, which I assume is the same PN as 1986+ cars. The VCV in my car is progressive, and the same PN as earlier cars. I put one on my 1984 300D, plus the 85 CA frame-mounted air cleaner. I see them often in CA junkyards and inexpensive. I may be going this Fri (1/2 off day) and recall a 1985 car, so might pull it to have a spare. If you get desperate PM me, but should be plenty there from 86+ cars. If limiting yourself to new M-B parts, your car will soon bankrupt you. Good luck.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

The 60X VCV is absolutely PROGRESSIVE, and serves as a throttle position signal. The combination of throttle position and manifold pressure is used as a surrogate measurement for load. Think about it this way: your description...'on' until a rubber seal is forced against the orifice...could just as easily apply to a kitchen faucet. The flow rate is determined by the volume of the gap between the orifice and the rubber seal. See the video:

http://www.coolcatcorp.com/Mercedes/IMG_4414.MOV