no 2-3 upshift and need car ASAP tks

[richclan]

i looked at lots of threads on this but nothing has worked yet.

leading up to this [FULL TIME] issue.

when cold no 2-3 upshift, warm seemed to do ok. 2 weeks ago

no engine shutdown 1 time only last week.

on a recent long trip would shift 2-3 at 3500-4000 rpm

now wont at all.

test results / troubleshooting

fluid level ok and recently replaced

19 hg at main vac tube

19 hg at shutoff valve

removed vac line to trans

removed bowden cable

unplugged kick down switch

history

b2 piston and 3rd gear spring replaced along with oil and filter 6k miles ago

3-4 shift has always been very fast and very hard

[vstech]

the very fast and hard 3-4 shift leads to bowden adjustment AND vacuum issues... bring up the "critical transmission vacuum" thread and get comfortable reading...

[Stretch]

This might sound a bit silly but does the oil smell smoky? (And you are 100% sure you've got the right fluid level aren't you?)

Other people have posted that cleaning out the governor has helped with a multitude of shift related problems after they've been checking vacuum and cables and the obvious...

[richclan]

oil is good and properly filled

this link It's CRITICAL... how you set your transmission's vacuum system on your diesel MBZ...

is 19hg at idle and though 2000 rpm to HIGH?????

[Zacharias]

19hg at idle is perfect, IIRC on my '85 it will drop slightly by 2000 rpms though, from very rough recollection to 17-ish?

When the bowden cable adjuster (on the valve cover) broke on my '82 SD it had roughly the same symptoms as yours. (The broken adjuster made the cable effectively longer.)

[Stretch]

There loads of information posted on Benz World here

DIY W123 Transmission Diagnose and Adjustment 722.xx OM 616-7 - Benzworld.org - Mercedes-Benz Discussion Forum

[richclan]

Originally Posted by Zacharias

19hg at idle is perfect, IIRC on my '85 it will drop slightly by 2000 rpms though, from very rough recollection to 17-ish?

When the bowden cable adjuster (on the valve cover) broke on my '82 SD it had roughly the same symptoms as yours. (The broken adjuster made the cable effectively longer.)

so the by disconnecting the cable it makes the shift rpm higher?????

[Zacharias]

Originally Posted by richclan

so the by disconnecting the cable it makes the shift rpm higher?????

Now that I think about it, I shouldn't have relied on memory there. I can't remember exactly what the car did with the cable messed up.

Anyway, I went back and dug up this thread: I would go with what VSTech says:

The truth about bowden cables

[newtodiesel]

If you can get your bowden cable reattached, you can adjust it by wedging some vacuum tubing along the cable. Slice the vac tube longways, then test for shifts. Keep shortening the vac tube until you get the right shift point.
Obviously the best thing to do would be replace the bowden cable if it is broken, but until you can get it fixed this hack will work. It has been working on mine now for about 8 months I broke the plastic screw adjuster

[richclan]

had a run in with a grinder, the grinder won. so i just got some time working on it.

the bushing on the shifter arm was shot so i made one for it. thats 1 issue fixed

bowden cable seems fine so i re-attached it

re attached the vac line to the trans

kick down sw. still disconnected by foot pedal

still wont shift into 3rd

disconnected vac tube to trans

will shift into 3rd and 4th now and not at a high rpm

vac line to trans holds vacuum

now what should i try next ????????

[Stretch]

...Governor...

...Is a possible fix - on the 722.3 you'll find it to be accessible from the outside at the back end of the transmission... take it out and clean it.

[richclan]

Originally Posted by Army

...Governor...

...Is a possible fix - on the 722.3 you'll find it to be accessible from the outside at the back end of the transmission... take it out and clean it.

if the governor is stuck would it shift almost normally with the vac. modulator tube disconnected?????

[Stretch]

Originally Posted by richclan

if the governor is stuck would it shift almost normally with the vac. modulator tube disconnected?????

Ahhhhhh errrrrr sorry I missed that bit...

If it is almost normally shifting with no vacuum attached but then not working with vacuum attached then that to my mind suggests a vacuum dashpot problem. They are pretty simple little things have you taken it off and cleaned it?

ATSG doesn't specify a specific solution to your problem (from what I can see). Problems "in your area" seem to involve the vacuum, control pressure regulating valve (this vacuum dashpot), throttle linkages, governor, throttle stop, and K1 clutch (also used in 4th so probably not the problem)...

[richclan]

vacuum dashpot
is that the blue saucer thing on dr fender, or is it the vcv on the inj. pump????

[Stretch]

Originally Posted by richclan

vacuum dashpot
is that the blue saucer thing on dr fender, or is it the vcv on the inj. pump????

Nope - you'll find it at the back of the transmission on the right hand side.