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e300diesel
Date registered: Sep 2013
Location: Palo Alto, California
Vehicle(s): 03 G55AMG, 06 E320CDI; 17 Sprinter Roadtrek
| Troubleshooting Rear Grinding noise
In my 2003 G55 AMG, @ 100K - I noticed a *mild* grinding noise only when decelerating (and always when decelerating), however, if I was in neutral or accelerating, the noise is not present. The grinding noise gets slower as the car slows down.
I am not the original owner, so I began the long process of troubleshooting and wanted to get feedback from the experts on the forum:
So here's what I did in order:
1) Replace Front and Rear Differential fluid (MB Spec fluid at MB dealer)
2) Replace all four tires, which were very old, with new Continental CrossContact LX20 + Roadforce balancing (<15lbs per wheel after balancing)
3) Replace all three transfer case seals (2 had very minor leaks)
4) Replace transfer case fluid (once leak repairs were verified)
Note: the transmission fluid was flushed at 88K, according to MB repair records
I shared this with my Inde Mechanic, and he believes that this is differential related, and I believe its coming from the rear differential. He has given the truck a good look, checking the bearings, the suspension and all moving components. He's not sure there is a differential repair/rebuild kit and since we had other bigger fish to fry, we figured we would wait to address that noise till later.
In a worst case scenario, I am thinking the previous owner drove on pavement with the differential's locked, and damaged the gears. In a best case scenario, I am hoping this is a simple adjustment of the pinion gears (if that is even possible) or there is something we've overlooked.
I would love to hear your feedback and advice on potential next steps, or other possibilities.
Thanks in advance,
Vinay
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Titus Pullo
Elite Veteran
Date registered: May 2007
Location: Ottawa, ON, Canada
Vehicle(s): '90 Wolf 240GD, '06 G270 CDI.
Posts: 1010
| Re: Troubleshooting Rear Grinding noise
when replacing rear dif. oil did you noticed a strange and unusual coloring of the oil and / or particles in it |
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Titus Pullo
Elite Veteran
Date registered: May 2007
Location: Ottawa, ON, Canada
Vehicle(s): '90 Wolf 240GD, '06 G270 CDI.
Posts: 1010
| Re: Troubleshooting Rear Grinding noise
no readjustments of the differentials possible. |
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e300diesel
Date registered: Sep 2013
Location: Palo Alto, California
Vehicle(s): 03 G55AMG, 06 E320CDI; 17 Sprinter Roadtrek
| Re: Troubleshooting Rear Grinding noise
The MB dealer did the differential flushes.
The dealer made no special of the color or metal shavings in either differential when I asked. I would imagine they would jump at any chance to capture the repair revenue if there was any chance it needed something.
Although in all fairness, at the time, I had no idea that grinding noise might be coming from the differentials, so I didn't really push the issue.
Is there a definitive way to isolate the noise to the differential, on a rack?
Should I go somewhere special to isolate the problem?
Thanks for the feedback so far.
Vinay
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: Troubleshooting Rear Grinding noise
I would also bet on it being a differential, probably the rear. There is a known issue with these. Debris caused by poor use of the lockers (ex: applying while spinning) will land in the nearby bearing and damage it. I'd get this looked at soon (remove cover from diff). If this goes on too long, the rollers can pop out of the cage and get into the gears, which is fatal for the the diff and possibly the axle.
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H1LM002G55
Expert
Date registered: Mar 2010
Location: S Florida / Geneva / Jeddah
Vehicle(s): 500 GE, G55, LM002, H1
Posts: 1796
| Re: Troubleshooting Rear Grinding noise
I agree with AlanMcR and his approach.
I guess changing Diff fluid every 15,000 - 20,000 MILES is *not* overkill to be on the safe side and to catch problems before they get worse.
Edited by H1LM002G55 10/28/2014 4:39 PM
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4x4abc
Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
| RE: Troubleshooting Rear Grinding noise
taking the cover off the diff does not reveal much
the damage is inside the side bearings
Karl had that happen a few years back
pretty catastrophic
this is a job for a well equipped shop |
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G-wagenaccessories
Date registered: Feb 2008
Location:
Vehicle(s): Mercedes-Benz
| RE: Troubleshooting Rear Grinding noise
If one continue to drive with the grinding noise from the rear axle, and it is confirmed the rear axle, the repairs can get expensive, or the axle needs to be replace completely.
The following images showed the damage to the differential, after a catastrophic side bearing failure.
The bearing's roller got eventually between the ring and pinion gears.....The axle was beyond repair.
The axle housing was cleaned as best as it could be done in the field (literally), cover replaced, new axle fluid, the rear drive shaft was remove,
and the truck was driven carefully for approx. 20Miles into the next town. Center diff locked, front wheel drive only!
 (Bearing Pieces.JPG)
 (Ring and Pinion Gear.JPG)
 (Cover deformed.JPG)
 (IMG_2500.JPG)
 (IMG_5722 (Custom).JPG)
Attachments
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 Bearing Pieces.JPG (144KB - 0 downloads)
Ring and Pinion Gear.JPG (103KB - 0 downloads)
Cover deformed.JPG (162KB - 0 downloads)
IMG_2500.JPG (209KB - 0 downloads)
IMG_5722 (Custom).JPG (129KB - 0 downloads)
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G-wagenaccessories
Date registered: Feb 2008
Location:
Vehicle(s): Mercedes-Benz
| RE: Troubleshooting Rear Grinding noise
Part II
The used replacement axle was inspected prior to installation.
After removing the diff cover and the side bearing caps, the discoloration of the left bearing race was noticed.
That prompted the decision to disassemble this axle further and repair as necessary.
The left side bearing roller cage showed some damage from metal debris, apparently small pieces from the diff lock teeth,
Some damage to the thrust washer inside the differential, all seemed to be related to the worn diff lock parts.
The outer wheel bearing got replaced as well, due to some weird appearances in the bearings seats.
The axles has been repaired and install as the replacement part.
 (Left bearing discoloration.JPG)
 (Left carrier bearing race.JPG)
 (Diff lock at carrier.JPG)
 (Dog lock teeth.JPG)
 (damage to thrust washer.JPG)
 (Wheel bearing seat.JPG)
 (Metal shavings.JPG)
 (small piece found in diff.JPG)
Attachments
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Left bearing discoloration.JPG (87KB - 0 downloads)
Left carrier bearing race.JPG (85KB - 0 downloads)
Diff lock at carrier.JPG (88KB - 0 downloads)
Dog lock teeth.JPG (86KB - 0 downloads)
damage to thrust washer.JPG (79KB - 0 downloads)
Wheel bearing seat.JPG (43KB - 0 downloads)
Metal shavings.JPG (62KB - 0 downloads)
small piece found in diff.JPG (109KB - 0 downloads)
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Troubleshooting Rear Grinding noise
Alas, this post is both timely and depressing as I have my G in at the MB dealer in an attempt to locate a very similar sounding noise/vibration. I have suspected the issue might be a differential problem, although for me, I think it is the front differential that is the culprit. When I replaced the right front CV boot I found a small metal piece that is virtually identical to the piece in the photo next to the penny. It was stuck in the machining center bore hole on the end of the axle. I did not realize the significance of it until I saw this thread. I will have to wait and see what the dealer says, but this is beginning to make some sense now.
- FD
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e300diesel
Date registered: Sep 2013
Location: Palo Alto, California
Vehicle(s): 03 G55AMG, 06 E320CDI; 17 Sprinter Roadtrek
| RE: Troubleshooting Rear Grinding noise
Folks,
Thanks for all of the input...the pictures are great, and give me a better sense of what I am dealing with.
What exactly is that last picture? Looks like a bent rod of some sort? titled: Attachments IMG_5722 (Custom).JPG
My Indy is pretty talented, but I want him to know what he will be getting into, cause he's a small shop.
So here are a few more questions:
1) Does anyone have a blow-up picture of the pieces involved with the Differential and Axle?
2) If its the side bearings that are known to fail, is it possible to just replace those...and dare I ask, is it complicated?
or
3) Do we have to start taking apart the entire differential piece by piece and inspect for damage and replace as necessary
I get the sense that if I have to do #3 I will not have a car for months while I am waiting for parts form Germany.
Appreciate the advice as I work through this scenario.
Thanks
Vinay
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Titus Pullo
Elite Veteran
Date registered: May 2007
Location: Ottawa, ON, Canada
Vehicle(s): '90 Wolf 240GD, '06 G270 CDI.
Posts: 1010
| RE: Troubleshooting Rear Grinding noise
#3 |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: Troubleshooting Rear Grinding noise
e300diesel - 10/30/2014 4:02 AM
Folks,
Thanks for all of the input...the pictures are great, and give me a better sense of what I am dealing with.
What exactly is that last picture? Looks like a bent rod of some sort? titled: Attachments IMG_5722 (Custom).JPG
3) Do we have to start taking apart the entire differential piece by piece and inspect for damage and replace as necessary
I get the sense that if I have to do #3 I will not have a car for months while I am waiting for parts form Germany.
The bent rod is the pusher lever in the diff lock slave that pushes the diff lock gear inside the axle tube into place when actuating the diff locks. They get bent when the diff locks are not operated properly.
Any MBUSA dealer should be able to get non-US stocked parts from Germany in a week to 10 days. They move things pretty quickly. |
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4x4abc
Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
| RE: Troubleshooting Rear Grinding noise
here is one of the 11 documents (8 axle, 3 drive shaft) I compiled for axle and drive shaft maintenance/repairs (:
http://rubicon-trail.com/pdf/3351fraxle.pdf
here is how to get the collection:
http://www.4x4abc.com/Mercedes-Benz.G-Class.manuals/bearing460.html
 (diff.jpg)
Attachments
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diff.jpg (180KB - 0 downloads)
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bimmerc
Veteran
Date registered: Jun 2009
Location: Alta, Norway
Vehicle(s): 1992 300GE swb Portals, 85 300GD STT Cab swb
Posts: 102
| RE: Troubleshooting Rear Grinding noise
For what it's worth I had a grinding noise from the rear when decelerating and also when reversing. The culprit was the engine mounts that were worn. The engine moved and this caused the exhaust to rub against the frame. No noise when accelerating. New mounts and noise disappeared! |
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