722.9 transmission query

[rmvembe]

On my 61' ML350 CDI, I've noticed the car will hold onto 6th gear and after a few seconds say up to 30secs, It will finally change into 7th. Once the shift into 7th is done, the transmission will shift through all 7 gears smoothly and timely. When this happens you can't manually change gear into 7th. This delay into 7th occurred since getting the car 2 years ago and has not bothered me. It's not occasional and happens 3/10 times. I had the box serviced a few days ago and the oil was not bad. There is no jerkiness, hard shifts or any of the 'faulty' transmission-related signs. Has anyone else experienced this?

Thanks you all in advance for your responses and comments

 

[W1ghty]

On my 61' ML350 CDI, I've noticed the car will hold onto 6th gear and after a few seconds say up to 30secs, It will finally change into 7th. Once the shift into 7th is done, the transmission will shift through all 7 gears smoothly and timely. When this happens you can't manually change gear into 7th. This delay into 7th occurred since getting the car 2 years ago and has not bothered me. It's not occasional and happens 3/10 times. I had the box serviced a few days ago and the oil was not bad. There is no jerkiness, hard shifts or any of the 'faulty' transmission-related signs. Has anyone else experienced this?

Thanks you all in advance for your responses and comments

Did the trans service improve the shifts ?
What did the specialist say about the shifting problem ?
Any fault codes on MB Star diagnostics ?

 

[rmvembe]

Did the trans service improve the shifts ?
What did the specialist say about the shifting problem ?
Any fault codes on MB Star diagnostics ?

Did the trans service improve the shifts ? Yes, they have improved, I had started noticing that cold shifts in the recent weather were not smooth. the new oil has solved this. Apart from the cold shifts, there were no other issues present. Flappy paddle changes work well up/down.

What did the specialist say about the shifting problem? TBH I didn't ask. I was meant to ask but the whole Covid handover process meant I didn't spend more time with the MB tech. They did scan the box before and after using STAR and nothing came up. From my side, I had a look using Autocom (delphi) and there are no stored codes on the engine or transmission. There were also no metal shavings on the magnet.

Any fault codes on MB Star diagnostics ? None

 

[W221copea]

I had the same symptoms with the car happily changing gear until the box was super hot on a long run then it would hold me in 5th. Kick down and it would then use 6th and 7th.

I had the box serviced (MB), oil, filters etc and was offered a software upgrade for many hundreds of pounds that i refused believing that Service History with main dealer would INCLUDE such needs for a car expected to last longer then me!

That aside - 5k miles later the torque converter started grumbling, was replaced (mega ouch) and the changes are like silk now.

Not diagnosing yours! just my experience. I was also told the car wouldn't be looking to shift to 7th until ~70 MPH, how true I have no idea.

 

[Jobsworth]

Mine has done this from new. I'm sure it's related to the temperature of the transmission oil, and it will hold the lower gear to get the oil up to temp quicker. In the summer it will use 7th within the first four miles of my commute, but lately with this cold weather it won't shift up until seven miles. The first three miles of my commute are quiet, slow roads, but I reach 60mph A road at about three and a half miles.

 

[rmvembe]

I've done some more driving and its looking like its temperature related. The only thing i can do is to keep tabs on it in warmer weather to see if the delay. This seems like one of those things that happens but only a few of us pay attention to.

 

[Jobsworth]

I've done some more driving and its looking like its temperature related. The only thing i can do is to keep tabs on it in warmer weather to see if the delay. This seems like one of those things that happens but only a few of us pay attention to.

I have owned mine from new, and of the 65,000 miles on it now, virtually all have been with me at the wheel. My wife is the only other, but not being a fan of it she has probably done no more than fifty of those miles herself. I am fairly in tune with the old girl. And the car