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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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Discussion Starter #1
2012 R350 4matic, 210k miles. But MLs and other 4matics will sound similar I suspect.

Getting a lot of noise from the front left (driver side) wheel when accelerating gently from standstill. Sound like cogs slipping over each other, kind of a rapid knock knock knock or clunk clunk clunk sound. At first I thought it might have been the suspension ball joint or steering rod end but I've just changed all those and the wheel bearings, and I didn't see any obvious damage to the suspension bushings either.

It only happens when accelerating from standstill (gently). I haven't tried accelerating hard for obvious reasons.

When driving along no clunks but a constant droning noise from the same area.
 

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E320/E250 Bluetec Ford F350 6.7l
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Kaput joint is when the engine revs high, transmission is in gear and you are not moving.
For damaged joint test, take in on empty parking lot, do max turn left and give it 2-second tap on the gas. Than repeat other direction.
You will know bad joint right away.
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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9,428 Posts
Discussion Starter #3
Mostly noise when turning left at corners, but also from left side when accelerating straight, slowly from low speed like at a traffic light or stop sign, and on inclines. Loud pops / bangs/ clacks, like I said it sounds like one set of gear teeth slipping over another, so I've ordered a driveshaft just in case. Not a genuine MB one, just a cheap aftermarket remanufactured (I think) one. I'll do the job properly if / when that one fails and I have more time and money.
 

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E320/E250 Bluetec Ford F350 6.7l
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Usually CV joints fail only when driven with torn boot for long time and sand replaced the grease.
But I had 1 occurrence where joint had perfect boot and took my professional friend to troubleshoot the differential, brakes and finally he took the joint apart to find the cage on it with crack.
It did not fail, but made noises.
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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9,428 Posts
Discussion Starter #5
Bear in mind I've got 200,000+ miles on my car, so I wouldn't be surprised if it's just worn out. The guy who pressed in the wheel bearings said he thought they were rusted in too, so a previous owner may have been using the thing in water too. I know I've taken it out in a few of Houston's heavy rain events as well.
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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Discussion Starter #6
Other thing I noticed was that there seemed to be quite a bit of "slack" in the axles. That is, I could push and pull on the axle as a whole and make it longer or shorter. If the axle is getting longer then it stands to reason the teeth on the two halves must be pulling apart, enabling one set to slip over the other.
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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Discussion Starter #8
I've run out of other ideas.
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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Discussion Starter #10
Well the replacement drive shaft arrived and on taking the old one out again, the new CV boot had come off, not split, just separated from the wheel end of the shaft, so I guess it may have been slipping as one part of the CV joint jumped over the other.

Another hour or two will tell.
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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Discussion Starter #11
No difference.

Bugger.

What's next? Transfer case? Differential?
 

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E320/E250 Bluetec Ford F350 6.7l
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I think you are making reverse troubleshooting.
You have strange noise that you can't locate, yet you start the topic asking about CV joints.
I think you need to start new topic with correct question.
Than you might want to take your car to a shop, who can lift the car with wheels in the air and move the drive shafts/axles by hand -looking for a play.
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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Discussion Starter #13
Yes. Having done all the obvious, starting with the cheapest. (which is what I'm trained to do - you don't replace the whole distributor if the car just needs new points being an old example), I'm now going to have to take it to a shop.

I did notice the transfer case has a chain in it and I'm wondering if that has stretched beyond its limits and is slipping over the sprocket(s).
 

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Discussion Starter #14
$2500 for a replacement transfer case $700 for an overhaul kit.
 

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Discussion Starter #15
Good news is the 18 year old Discovery just passed its state inspection...
 

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2008 AMG CLK63 Conv., 2012 R350 4-Matic, Wife's 2015 C300 sedan
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Discussion Starter #16
Took the R350 into the local, honest, transmission shop. Transfer case chain is stretched beyond its limit and the noise is coming from the chain jumping over the sprockets.
 
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