Ed52525

The transmission of my 2005 E320 CDI has begun to shudder or shake at low speeds and RPMs It seems the transmission stays in high gears longer than normal at low speed resulting in low RPMs. It is especially noticable when driving uphill slowly. Throttle will downshift the transmission for a while. The car never showed any shudder or shake when going uphill at low speeds until the last year or so. Any suggestions will be appreciated.

kajtek1

Mileage, when was the last service done age of pilot bushing?
Any codes?

Ed52525

About 148,000 miles. The transmission was serviced about 30,000 ago. The pilot bushing age is unknown, likely original. There are no codes indicated but I'll connect a reader tomorrow and see if it shows anything. I'm going to try switching from Comfort to Sport mode when climbing the hill and see if that makes a difference.

kajtek1

Here is your answer. Orings on those bushings usually last about 8 years and then ATF floods the harness and TCM.
Will you get SD-level scanner - most likely you will have speed sensor code.

Ed52525

Thank you kajtek1. I'll find an SD-level scanner and get a read.

Tschuss_Bill

Check for codes, check for leaks, all good advice. If you have no codes and no leaky pilot bushing. You may have someting amiss with the torque converter lockup circuit, the torque converter lock up clutch pack or both.

I too have a 2005 E320 CDI. I had this problem only when the car was cold and it was below 50F. The car would seem to jerk into 2nd gear at slow speeds, that was actually not a gear change but the TCLU engaging harshly. Slow speed deceleration, I'd get groaning. I noticed the tach dipping down to 500rpm before bouncing back to idle. Again the TCLU disengaging late and abruptly.

I had no codes and the dealer said officially to replace the torque converter, valve body and transmission. Unofficially the recommendation was to get the valve body and torque converter overhauled. I found a good auto trans shop that knew the 722.6 trans as well as familiar with sonnax updates. Sonnax updates include a couple engineered improvements to the original design.

Please post what you find out!

Ed52525

Thanks Tschuss Bill for the additional info. I had my wife switch the transmission to sport (S) mode tonight when she drove up the hill. She reported that there was no more shuddering. I will be working on the MB tomorrow and doing some drive tests. I'll report more later.

cetialpha5

I believe the pilot bushing is quite cheap, I'd just change that and see what happens. Mine was doing something similar, harsh shifting. Change the fluid and bushing and it's back to being smooth.

kajtek1

You also need to wash the contamination from plug and check if ATF made it to TCM

konigstiger

Ed52525 see here: https://www.sonnax.com/valve_body_layouts - find parts by unit –Mercedes 722.6 - valve body layout

Ed52525

Thank you for all of the support. I will be looking into the problem during the next few days. I really appreciate the technical expertise available at this forum.

Ed52525

I removed the electrical connector from the front right side of the transmission and 5-10 drops of ATF dripped out. I don't have a replacement connector yet so I will attempt to clean it up with contact cleaner and then reassemble for now. The transmission fluid level appears ok but there is some small ATF leakage at the rear of the transmission.

Ed52525

The transmission problem has been repaired. I dropped the transmission drain pan and cleaned everything, replaced the filter and replaced the electrical connector receptacle (pilot bushing). The fluid was dark brown/black so it was long overdue for changing. The pilot bushing showed ATF leakage. I also flushed 6 quarts of Mobile AFT-134 through the system using the transmission cooler hose connection near the radiator. The flushed coolant was mostly red after 6 quarts. I'm planning to flush the system every 30 to 45k miles from now on. The transmission now shifts normally and is completely smooth with no shuddering. I think it has had problems and was vibrating/shaking in almost all gears at low RPMs and I had not noticed it. Thanks to everyone helping me with this problem.

CDIJeff

Yeah, mine has around the same amount of miles same year to, fluid was also kinda nasty looking.
I flushed my transmission fluid about 3 or 4 times and it completely changed the shifting for the better.
When I went to change my pilot bushing while doing my filter/gasket it didn't fit, so that told me someone changed the conductor plate. Amazon you linked somone had the same problem in the reviews.
I cleaned the old plastic and then just switched over the gasket, been holding up fine for 30k miles.
I just used Valvoline Maxlife transmission fluid 722.6 are not that picky, compared to the 722.9.