Does this transmission use vacuum control to shift smoothly? If so where can I find the unit and test it? I am asking because it shifts hard most of the time and the auxillary vacuum pump cycles for a while after start up. Just wondering if they are related. I do not hear any hissing noise to be able to find where vacuum leak could be. Thanks.

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If it ain't broke take it apart and find out why.

1983 300SD, 4 speed
1994 C280
1987 300TD wagon
1996 HD Road King

Ride in Peace Eric Peterson, Harley of Macon

Yes, the transmission uses a vacuum modulator. The vacuum line connects to the intake with a rubber hose. IF that hose is disconnected, the trans will shift harsh.

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MERCEDES Benz Master Guild Technician (6 TIMES)
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MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
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Retired Moderator

or the hose could be cracked or have a hole in it... might need to be inspected

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1994 C280
2009 VW Tiguan
1993 Toyota X-tra Cab SE-5


1973 220D ... Gone, but not forgotten
1991 Alfa Romeo 164L Gone, wife MADE me forget it

2006 Hyundai Tucson... just straight out FORGOTTEN!

Thank you M.B.DOC!! I checked the black vacuum line and found it disconnected. When I tried to hook it back up the rubber connector disentegrated. It took awhile to work a new piece on to the modulator body, BUT man she shifts pretty smooth now!! On to the next...........!

__________________
If it ain't broke take it apart and find out why.

1983 300SD, 4 speed
1994 C280
1987 300TD wagon
1996 HD Road King

Ride in Peace Eric Peterson, Harley of Macon