Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 12-21-2015, 05:39 PM
ashedd's Avatar
Registered User
 
Join Date: Aug 2008
Location: Seattle
Posts: 1,790
R320 7G-tronic service bulletin?

2008 R320 CDI with 7G-tronic

Does anyone have info on a service bulletin about this transmission slipping?

Mine started to shudder last summer, got the fluid changed, shudder went away. Now it's back, my indie can reproduce the problem, and now MB dealer says the same.

They say: "Our leach Tech with transmission issues cannot find one fault with your transmission. All the clutch values internally are all within spec. There are no stored fault codes. And same with the rattle noise. Everything is solid with no noise at this time.He feels as if there is no need to dive into the issue at this time. Possibly have to wait for it to get worse. Or do a overnight test drive."

It shudders from about 35-45 mph with moderate power, like when getting on freeway, or pulling out in front of traffic. You have to give it power/torque to just before it downshifts. It goes away after the downshift.

I'm pretty sure I've read about slipping and a service bulletin about a software update.

I need to tow my boat!


__________________
08 R320 CDI current

Past
95 E420
87 300D Turbo 5spd
90 300TE
83 300SD
85 300TD
92 400E
85 190D

Reply With Quote
  #2  
Old 12-21-2015, 07:44 PM
Registered User
 
Join Date: Jan 2012
Posts: 7,534
With the description you give, it sounds like torsional vibration not slippage.

Search for the following " Sprinter RSN ( Rumble Strip Noise ) " , " 722.6 torque converter drag " " Sonnax 722.6 torque converter fix ". Yes, I know the 722.6 is the 5 speed just prior to yours but the principles are the same.

Also try these. 722.6, 722.9 - Sonnax

My MB E320 Sedan Story, a.k.a.

Mercedes 722.6: Cold Stall/TCC Shudder, Part 1 - Sonnax

Mercedes 722.6: Cold Stall/TCC Shudder, Part 2 - Sonnax

Torsional vibration is like driving a standard shift in too high of a gear / engine RPM too low. In your case, what happens is the torque converter clutch could be dragging / being commanded to apply at too high a percentage of lockup causing the shudder. These lockups are modulated from 0 to 95% of lockup rather than an on / off arrangement. If the dealer scan tool could reduce the amount of torque converter lockup that would be great but I don't know if that is possible.

You need to drive the car with a tech in the passenger seat. The techs might have a slightly different driving style and sometimes it takes a very narrow set of circumstances to uncover the shudder.

The new fluid may have had a different friction coefficient and been more slippery allowing for less TC lockup. Now that the fluid has been used for a while it is more grippy resulting in greater lockup %.

A work around would be to apply less or more throttle to stay out of the vibration range. Less throttle = less load , more throttle = downshift / less lockup.

I have a 97 SL320 and 97 C280 that exhibit torsional vibration at light throttle in the same speed range. In general the transmission won't damage itself other than in the very very long term the hammering could take some life out of the drive train.
Reply With Quote
  #3  
Old 12-21-2015, 08:24 PM
Registered User
 
Join Date: Oct 2004
Posts: 4,104
I've never seen software fix a shudder in a 722.9. It sounds like your torque converter is failing. Seen it more than once. The problem is that if it has enough mileage to beat a converter the rest of the trans isn't far behind. The .9 series just isn't that long lived of a box. My advice is trade it for a similar vintage Jeep. You get to keep the 642 engine and get a .6 series behind it.
__________________

90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE
104.980
Milled & ported head, 10.3:1 compression
197 intake cam w/20 advancer
Tuned CIS ECU
4 ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff
Reply With Quote
  #4  
Old 12-22-2015, 11:58 AM
ILUVMILS's Avatar
Senior Member
 
Join Date: Sep 2002
Posts: 3,047
Textbook description of TC lock-up issue. First step should be to FLUSH the transmission and cooler. Simply changing the fluid may help in the near term but flushing should do the trick........
Reply With Quote
  #5  
Old 12-22-2015, 01:49 PM
ashedd's Avatar
Registered User
 
Join Date: Aug 2008
Location: Seattle
Posts: 1,790
Thanks for the replies.

They did two software updates and report the problem solved. It did do some funky stuff on the drive home but I'll give it time to settle down before I call them back.

Not sure how to force them to look at the torque converter. My third party warranty says it covers torque converters. But dealer needs to specify that it needs replaced.

They told me a rattle my indie diagnosed at exhaust related is a leaking injector. Tech said to replace soon or something he called Black Death is likely. I don't know much about these newer diesels. Not like it's a 617 or 603 or something.

My indie has missed a few things so far, and they are a highly regarded MB shop.

I got 2015 GLK350 loaner, seemed nice. Would like a diesel but I understand they're around 50k!
Reply With Quote
  #6  
Old 12-22-2015, 01:50 PM
ashedd's Avatar
Registered User
 
Join Date: Aug 2008
Location: Seattle
Posts: 1,790
I need to toe my 18' boat across town soon, think I'm ok?

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 07:10 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page