... on top of the fuel pump, with vacuum lines attached.
Transmission won't engage the first gear, unless I'm rolling.
Anybody knows the correct name or part number?

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Vacuum control valve. As of a few years ago no longer available new.

Did this just happen or did you get the car this way?

The modulator is a controlled leak - should allow more vacuum to transmission with less pedal input, less vacuum with more pedal input. Harsh shifts suggest vacuum isn’t getting to the transmission or the transmission isn’t processing the signal. The modulator on the transmission at the other end of the vacuum line should hold vacuum and shouldn’t leak ATF. Make sure the rubber cap on the modulator is in place and not cracked. Break out the MityVac and gauge and get testing!

Sixto
98 E320s sedan and wagon
02 C320 wagon

Thanks for the reply. I found this thread:

http://www.peachparts.com/shopforum/diesel-discussion/356706-car-down-need-help-sourcing-vacuum-control-valve-vcv-84-300sd-w126.html

I have the car since 12 years. It's been shifting funky recently, but then was normal again. As of this morning, it wouldn't engage the first gear unless I was rolling, it would go in second gear.

My mechanic is doing the work. I have to talk with him in the morning, if he checked the modulator as well. It was late already, he may have only checked the VCV.
It seems, based on the thread, there is a good chance, the modulator is failing.
Are those available new?

Yes, modulators are readily available.

B2 pistonleaking symptoms...

The SD starts in 2nd, then drops to first under acceleration.

I agree, test black line, make sure hose is intact at modulator , test for holding vacuum

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Mechanic says he checked and tested everything, all lines, modulator & VCV.
I grabbed a couple of those VCVs off eBay. We'll see what happens.
Thanks for the input guys.

How about a pic of the VCVs that you bought on Ebay.

You will need a Mityvac or something similar; do you have one? Retraction - looks like you are not doing your own wrenching.

At this point I vote on the B2; here is a shift chart so you can see what B's and K's are used for shifts:

http://www.peachparts.com/shopforum/attachments/tech-help/95541d1315505905-please-help-560sel-722-350-transmission-problem-screenshot-49.jpg

I have absolutely no idea what you are referring to by B2, B's & K's?
The VCVs are part number 1230700046

And no, mechanic is doing the work. I am just buying the part he's telling me I need.

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The VCV controls vacuum to the modulator. It is there to soften shifts.

B's and K's in the shift chart refer to which brake band (B) or clutch pack (K) is engaged for a given gear.

The B2 piston is internal to the transmission and controls the brake band on the gear assembly. Transmissions wear out, when they do, things start misbehaving. A leaking seal or worn cylinder will cause fluid pressure leakage and affect operation. The more brakes or clutches are engaged, the more critical the pressure leakage becomes.

__________________
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!)

What we are saying is that it may not be a vac problem.

Ok, I get it.
That indicates, the VCV replacement might not resolve the issue.
The transmission was rebuilt in 2012. I put lots of miles on the car since then.
If internal transmission work is required, it will be another decision to be made.

We'll find out.
It may well be a brake/clutch pack issue.

Out of curiosity, has the fluid level been checked or the transmission serviced with new fluid and a fresh filter in the last 30K miles or so? A low fluid level or plugged filter can certainly cause drivability concerns.

__________________
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!)

ATF level and color is fine, looks very clean. Has been serviced last January, which is maybe 5k miles since then.

I was just looking at your 300 SDL thread. There is one near by 4 sale, 260k miles very clean, around $4k.
I was wondering, if those cars are as reliable as the 5 cylinder turbo.
I like the long wheelbase. Would be a cool cruiser.

Mine's ROUGH, definitely not a good example to make comparisons against. However, given it's rough history, shaky start to its resurrection, and unknown actual mileage (I suspect well over 250K miles), it's never let me down. Other than the numerous unusual electrical problems I've had (I suspect someone connected a battery backwards at some point), it's been dead reliable. Starts immediately, makes good power, super comfortable on the highway, frosty A/C.

I'd say the $4K asking price is high (though I haven't seen the car), but if you could get it for a fair price, they're a nice ride. The big "scary thing" that everyone bangs on about on the 603 is the #14 head casting being weak. Check for coolant consumption or a pressurized cooling system when cold. Otherwise, keep them maintained and they're just as reliable, if not moreso (I'm sure I'll be flamed for that claim), than the 617.

__________________
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!)