Hello fellow Benz owners! I have a question/issue on how to proceed with my wife's 2014 ML350 4MATIC with 100k miles. We are noticing an intermittent slipping somewhere in the middle of 5th gear with a minor 50-100RPM flicker seen on the RPM gauge. It's very subtle and all gear shifts up and down seem to work as expected. The blue fluid was changed by me in 2024 along with the filter and gasket, and I just double checked the fluid level is correct at 45C over the weekend to be sure I didn't under or overfill it previously. It does have a remanufactured transmission from back in late 2016 performed by Mercedes while under warranty due to a shudder issue, which we still feel occasionally, but it's subtle and just figured it's a characteristic of some of these ML350s. I've done a full scan using the YOUCANIC, and I have never had any trouble codes (stored or current) show up, so whatever is happening is not enough to trigger any warnings or errors by the TCU/ECU. I'm in the the middle of a relearn of the shift points now after doing a reset of adaptation values using my YOUCANIC scanner. I'm hoping that will fix it, but I can still feel the slip now while doing the relearn so not sure it will have any impact.

I'm considering replacing the o-rings on the K3 solenoid (maybe all solenoid o rings?) since I believe the K3 clutch first engages at 5th gear, but I'm not sure if that will help or not. I have done a lot of DIY auto repairs before but never rebuilt any engines or transmissions.

I'm hoping there are some folks on here that might have experienced something similar and can help me out before I drop lots of money at the dealership or an independent mechanic. I'm in the Memphis area. Thanks in advance and hope you are all enjoying your weekend!

 

Don't drop a lot of money to replace parts you don't know are bad to get limited improvements.

Based on circumstances I consider your TC clutch is not getting locked for some reasons...

Look at the TCU data for evidence of what is happening then you can throw a rebuild kit at your tranny with confidence.

 

Thanks for the helpful response! I will see if I can find the TCU data you mentioned. I’m curious if doing a reset learned torque converter values using my youcanic scanner would be helpful followed by a relearn by driving. There is a respectable transmission shop in Bartlett area that said they will diagnose for $165 so I’m considering going that route. This shop was recommended by Wolfsburg Automotive who works exclusively on VW, Audi and Porsche so I trust their referral. Thanks again and cheers!

 

I don't know what youcanic scanner can do... some ppl have reported wiping adaptations was a seriously bad move.

Use your scanner to read TCU data without wiping anything will do no harm.