'84 300D shifting woes - need advice - PeachParts Mercedes-Benz Forum

67V35er · #1 07-15-2008, 04:43 PM

Can someone with some good experience on diagnosing/resolving automatic shifting issues offer some assitance?

My newly acquired 300D shifts harsh which, after reading applicable posts, seems to be vacuum related. I'll troubleshoot the vacuum problem this weekend in hopes at smoothing things out. The tranny was recently rebuilt by a reputable MB shop so I'm not expecting to have any internal tranny problems.

Here are the symptoms - unless otherwise specified, they are based on a level road:
1) All shifts are harsh - except when under a load such as climbing a small incline / hill - and then it shifts noticably smoother.
2) It shifts from 1st to 2nd at a seemingly high RPM.
3) Then it shifts from 2nd to 3rd in almost an instant - almost like bypassing 2nd, This does not happen all the time but on certain conditions.
4) On the slightest of inclines (and below approx. 45-50 MPH) it will downshift from 4th to 3rd when there is still plenty of power in 4th to pull the car.

My main concerns are items 2, 3 and 4 and how to go about correcting them.

I've been able to sometimes master the soft shoe shuffle with my right foot on the pedal to try and smooth out the shifts but admittedly, that has been a roll of the dice.

Any suggestions would be appreciated. I have no service manual yet but will get one this weekend.

Thanks for any help to a new MB 300D caretaker!

Cr from Texas · #2 07-15-2008, 04:48 PM

Quote:

Originally Posted by 67V35er

Can someone with some good experience on diagnosing/resolving automatic shifting issues offer some assitance?

My newly acquired 300D shifts harsh which, after reading applicable posts, seems to be vacuum related. I'll troubleshoot the vacuum problem this weekend in hopes at smoothing things out. The tranny was recently rebuilt by a reputable MB shop so I'm not expecting to have any internal tranny problems.

Here are the symptoms - unless otherwise specified, they are based on a level road:
1) All shifts are harsh - except when under a load such as climbing a small incline / hill - and then it shifts noticably smoother.
2) It shifts from 1st to 2nd at a seemingly high RPM.
3) Then it shifts from second to 3rd in almost an instant - almost like bypassing 3rd, This does not happen all the time but on certain conditions.
4) On the slightest of inclines (and below approx. 45-50 MPH) it will downshift from 4th to 3rd when there is still plenty of power in 4th to pull the car.

My main concerns are items 2, 3 and 4 and how to go about correcting them.

I've been able to sometimes master the soft shoe shuffle with my right foot on the pedal to try and smooth out the shifts but admittedly, that has been a roll of the dice.

Any suggestions would be appreciated. I have no service manual yet but will get one this weekend.

Thanks for any help to a new MB 300D caretaker!

There is a really good thread on adjusting the vacuum for transmissions. Start there and post to that thread.

http://www.peachparts.com/shopforum/diesel-discussion/158216-its-critical-how-you-set-your-transmissions-vacuum-system-your-diesel-mbz-post1909316.html#post1909316

67V35er · #3 07-15-2008, 04:58 PM

Looked at the thread and - wow! There's a lot of info there that will make for great learning and hopefully some positive results. Will post there as suggested.

Thanks for the direction.