1993 Mercedes 190E 2.6 petrol w/722.409 tranny - PeachParts Mercedes-Benz Forum

wirewilly · #1 03-24-2014, 04:31 PM

Just bought this car with 92k on it, fixing all problems I inherited, one problem I've not identified is the transmission is not upshifting into 4th gear. I don't have a vacuum gauge or experience in testing this unit to trace possible vacuum component defects. So I'm hoping someone who knows the common malfunctions with this unit might advise me on what goes wrong.

Procedures done already, pulled transmission pan check filter & installed new one. Pan, filter, & fluid was all clean and new free of any fragments or burned fluid. visual & listening for vacuum leaks for transmission system, nothing identified as of yet. looked at vacuum control element for the adjusting pressure screw, can't see or find screw near transmission cable on the element, very tough location for finding on jack-stands on your back.

Kick-down works great so it's NOT the switch near accelerator pedal. I've played with the linkage adjustments near the CFI throttle body correcting the RPMS at idle to 750 and adjusted the Bowden cable on aggressive side when stepping on the throttle.

I've done about a half dozen run-ups on jack stands where wheels start turning 5,10, & about 15 mph the speedometer jumps online at 15mph or no speedometer mph indication prior to hitting around 15 or 20mph this wrong function stays pretty much consistent, with one exception of 1 run-up where I could tell 4th gear was kicking in and RPMS were what they should be 1000RPMS per 20MPH etc.

Currently or i.e. most of the run-ups RPMs are high like it's stuck in 3rd or 3700RPMS at 60MPH. Someone who knows this system should be able to steer me to the right problem or component. Please do if you know these cars well and what goes specifically funky on this issue I've describe in detail. Thanks

JamesDean · #2 03-25-2014, 12:40 AM

A few quick comments:

1) On these 722.3 and 722.4 series transmissions vacuum is used to soften the shifts only. It has no control over whether or not they occur.

2) Google up "atsg 722.4" and you'll find a most helpful PDF that might help you figure out your problem.

Perhaps you've got something wrong with your K2 accumulator/clutch/etc. The PDF indicates that its used for 4th gear (as best as I can figure at least).

Not sure if it will help at all but Superior Transmissions has a spring kit for the valve body. Maybe a broken spring in the K2 accumulator can cause this? Maybe not.

This might be helpful too
http://www.atraonline.com/gears/2008/2008-07/2008_7_38.pdf

wirewilly · #3 04-16-2014, 09:34 AM

JamesDean, Thanks for your information resources and help. This information helps me and may very well be the spot on remedy I'm dealing with. I think I'll look for a replacement control valve kit for the valve body on this unit after reading the pdf file with same problem I have. Sorry it took so long to respond I just now read your information 3 weeks after you posted it.

I have not solved this problem yet but now have a clue on my next repair phase for the specific problem. Thank you so much, I have all this information on file and when I get the car on the road I'll be able to see how the Cruise control functions, so far just a jack stand test seems to shut on and off ok for now.

JamesDean · #4 04-16-2014, 12:10 PM

Glad I could help.

Superior Transmission - Superior K722A-G

Transmission Part by Bulk Part Valve body kits Shift correction package 722.3 / 722.4 Gas