As the title suggests, the noise is more like a chain slipping on hard acceleration. Googled but couldn't find anything related to ML's, a few youtube videos poped up of transfer chain problems, I am guessing the noise is exactly the same as when you have a transfer chain slipping. But I want to know if that is the problem with my Merc. Has anyone ever had an issue with transfer chain on W164s? Mines a 320 CDi Sport and it makes an ugly slipping noise on hard acceleration.

Please see below video, my car is making exact same noise when accelerated hard

yup, its the chain in the transfer case that has stretched over time. needs to be changed

My local garage is having a look at it, after a test drive, mechanics initial thought is something wrong in the differential. They will confirm what is the actual problem tomorrow.

Have you had this problem with your ML as well poolmanEd?

yes I was able to get the chain from Anaheim gears in California. make sure you give them the correct year and model and they will definitely have it, I also had a piece broken in the transfer case which help keep the tension. had to be welded (aluminum)
Hope that helps. Maybe didn't need the chain but while it was open I changed it.

Hello,

Long shot I know, but did you get this diagnosed as the transfer chain of the front diff BikeRider? Having the same noise and wanted to double check before I start my investigations. Any help gratefully received!

He only has two posts in the last 4 yrs. , so I doubt he will respond.

Yep, its definitely a long shot! Actually just looking at one of your other posts with the video link for changing the ATF in the transfer case - going to give that a shot first! So thank you! Fingers crossed it will work, if not I will look to replace the chain.

The transfer cases in these vehicles go bad quite often.

First change the ATF in the transfer case and see if that fixes it. Mine got quieter for a few weeks then started being noisy again.. so had to replace it.

Best to buy a low mileage used unit. The chain is not the problem, it is the tensioner. Yes they can be repaired but it's part of the casing so much easier to buy a used one and put it in.

Mine went somewhere around 200,000km (120,000 mi) so I found a low mileage one from a wrecking yard and should be good for a while.

Make sure to OVERFILL the unit. I am convinced that they were too low on lubricant from the factory, and over time they wear out. I think we got almost 1/2 liter of extra fluid into mine (squirt it in fast and put the plug in. Very little risk of issues with overfilling (they take very little fluid in the first place!) and you are better off having it over filled rather than under.

I have over 100,000km (60,000 mi) since replacing and overfilling, and not a noise at all.

Trans. fluid is sheet 236.14. Transfer Case fluid is sheet236.12.

https://bevo.mercedes-benz.com/bevol...236.12_en.html

Thanks is fantastic. Thanks to both of you. I really appreciate your experience and input. I have ordered some of the correct spec'ed fluid and promise to update this post with the outcome. Thanks again!

Just, thought I would give an update on this for anyone who might search in the future. Car is booked into a gearbox and transfer case specialist for diagnosis - I'll post the results here.

But I few things I found out along the way:
- Getting hold of a low mileage transfer case for the 420CDI is very difficult in the UK. The best I found was 155k at £350+ VAT through Motorhog.
- A fully refurbished Transfer case is around £900 plus VAT
- Labour time for the replacement is around 3hrs
- Total for fully refurbed fitted is around £1250
- I have hoping its just the chain that needs doing - so it will be less.

Useful places in the UK:
Bexhill Gearboxes and Transmission (near Hastings) - will do full diagnosis and repair what is necessary. Really friendly and helpful
JPAT (based near Bath) - will post a new TC for another garage to fit. You send them back the old one. But most garages I spoke aren't happy using part bought by the customer.
A1 Transmissions Bolton - super friendly and helpful bloke called Harry, seems to specialise more in manual gearboxes, but did a lot of research on my behalf and was very helpful. Definitely on my list for future
Bristol Transmissions - also do this kind of work, both with the car there or postal service. Too far for me though.
Hardy Engineering (Leatherhead) - super helpful and do the work.

And some useful links for parts...

https://jpat.co.uk/uploads/1/0/3/5/1...desbenzdcs.pdf
I think the part number ends in 1300 for the 420cdi. Not 100% though.

http://mbepc.net/1/fg/ml/63j/164128/0/28/010

Wow, another with a 420. I thought it was just me!

Good luck with your fix.

gidday poolman, how many miles has your ML320 CDI done? cheers from New Zealand

Hi ted, how much mileage do you get out of a 420CDI from a full tank? Cheers