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nash
12-14-2013, 01:45 PM
Purchased a new 2012 12 passenger in 9/13 with 1800 miles on the odometer. Two issues, one seemed to have resolved by way of the other problem, I will explain.
1st issue: Accelerating at a very modest rate from a standing start there would be a "bump" from the rear of the vehicle. If I accelerated at a very slow rate there would be no bump.
2nd issue: after the van had sat all night I have experienced on several occasions that within the first 1/4 mile driving, from a stand still, the transmission would feel as if the clutch was not fully engaged on a manual transmission, this of course is an automatic! My morning routine is to back out of my drive, put in "drive" and travel normally to the first stop sign 100 yards, stop, accelerate normally to the next stop sign, stop, but then as I would begin to accelerate the van would just creep forward. RPMs in the 2500 range until several seconds later it would fully engage. I would experience normal acceleration for the rest of the day.
Recently the same issue occurred where the transmission did not fully engage. I pressed the accelerator down till rpms were in the 3500 range. Van crept along for 20 feet until the all of sudden it engaged abruptly. Since that incident my 1st issue has been resolved, no more “bump”!
Temperatures outside have been from 20-45 degrees. I park the van facing uphill slightly.
Any feedback with similar experiences or suggestions on what is going on would be greatly appreciated. Local MB dealer has not been able to duplicate the 2nd issue. No codes. No updates to software required.

sailquik
12-14-2013, 03:46 PM
nash,
Are you sure you aren't confusing the cold weather mode of the transmission with something being wrong with it?
When you start out in the morning, watch your tachometer. It will tell you when the transmission is "auto" upshifting.
When starting out from cold, your engine management system will hold the transmission in the lower gears for significantly
longer.
My 2012 170" wb cargo would not upshift from 2nd gear until the RPM reached 2800 RPM...even on perfectly level roads.
Since I have a small hill to climb after running 1/8 mile on a dirt/gravel road, then another 1/4 mile on a 20 mph unmaintained
blacktop road, then up the hill, my Sprinter would run in 1st and 2nd gear @ higher than normal revs (<2800) until I start up the
hill, then near the top of the grade it would upshift @ 2800 RPM to 3rd gear.
When it upshifts @ 2800 RPM it's a little more abrupt than when the transmission and engine are warmed up.
All of this strange "cold start" behavior is designed into your Sprinter to get the engine to warm up more quickly and
reduce it's cold start emissions profile.
As far as the "bump" from the rear end, I would make sure that the dealer did the mandatory re-torque of the rear axle to rear
spring mounting u-bolts.
It may be that your Sprinter's engine management is just doing what it was programmed to do, but that is enough different that
it seems to be mal functioning to you.
Hope this helps.
Roger

nash
12-14-2013, 07:20 PM
Sailquik, the vehicle is barely moving in my situation. Imagine a manual shift situation when just barely bring the clutch out, just teasing it along, engine revs up, but just barely moving forward; that is what it feels like.

NelsonSprinter
12-14-2013, 08:28 PM
Common on some transmissions if the fluid is 3/4 quart low to have this slipping, especially when the cold contracts the fluid to less volume

nash
12-15-2013, 04:39 PM
I have passed your suggestion to the dealer, thanks.

nash
12-27-2013, 02:35 PM
Transmission fluid levels reported to be fine. No codes or software updates.

Had rpm's over 3,500 the other day when I first set out, van barely inched forward. I did manually drop it into 1st gear and then forward motion returned to normal. Don't know if changing gears had actually did the trick or transmission finally engaged.

Bump I have felt from a standing start returned too!

vitola231
12-27-2013, 03:10 PM
I have always had this to, no amount of warming up will help either. just slips for a few blocks when cold out than starts working. these aren't special transmissions by any means, any trany shop can help. thought I had read article with jeep where they modified it to prevent this. I know, it sucks because you know by moving it like this your making the problem worse or wearing something, I say just drive it or bring to tranny shop. good luck.

wiartonallan
06-11-2015, 08:42 PM
I have the exact same symptoms with my 08 Frieghtliner 2500 85000 miles. Recent fluid and filter change. More recent level check.

If the transmission is loaded (like on a grade) when cold it behaves as if the torque converter does not even begin to lock up.

If I pull away on a downslope or on the level with no resistance operation is normal.

If the engine (and transmission?) are warmed up- no issue.