Noise with differrential?~
 

With the heavy snow last week my wife noticed that there was a kinda shimy noise in the 1999 ML320 when driving. The wining gets louder and at a higher frequency as I go faster. My trusty eastern europen mechanic says it might be the differential, but he's doing more test. I trust this guy, he's always fair and has worked on my 1984 300D the last 2 years. Last week, the rear passenger window didn't work on the ML. Mercedes said the regulator needs to be replaced for $700. This mechanic fixed it with a $15 part. Now the ML has 54,800 miles on it and I had Mecedes do a full tune-up at 49,000 miles. If it is the expensive differential, what are my chances that I can get Mercedes Benz to fix it on warranty which expired at 50,000 miles. This ML are given me plenty of electrical trouble and the engine rings were rebuilt at 31,000 after I complained since 19,000 of it drinking oil like a lush. This is my 3rd leased MB and frankly, they don't make them like they used to anymore, especially the ML. Thanks for your insights, guys.

doubt its the differential...
 

You can check the differential fluid level.. Its probably the suspension! the ML suspension isn't very good, alot of forum members have already changed theres unfortunately. and about the window regulator, its probably the window switch.. he probably just repaired the switch thats why it costs $15 only.

I don't think it's your diff! more...
 

I am having the same problem at pretty much the same mileage (59K....see the shimmy, steering wheel post) and I checked and topped off both diffs hoping it was just a low fluid level. It wasn't. My "mechanic whom I also believe says that he called dealer his "contact at dealer" said that these diffs have a bearing at the input shaft that can go bad and needs to be replaced "occasionally". I emailed Gilly privately and he said that he had not heard of that before so now I am confused too. Please email me privately and perhaps we can compare, etc to determine correct fault.

Joe Hahn

Check the driveshaft center bearing!

How?
 

Check ourselves or take it in to someone? Please let me know.

Joe Hahn

You'll have to bring it to someone. My problem was diagnosed by the dealer but I also have a friend of mine who is a Ford master tech who put the truck on a hoist who show me where the center bearing is and the rubber mount of the center bearing was totally mushed and the bearing is loose. It seems like a common problem. Just look at the post we have today.

true about this post! anyway, any idea about how serious (cost?) a repair is? I am sure under warranty it showed up as "N/C" which is always delightful but I am trying to return this thing in 2 mos and I am outta warranty!

Remember that movie Memphis Belle that just had the plane that needed to make it one more bombing mission before the crew/plane could retire....I am now christening my ML "Memphis Belle" as each trip is riddled with anxiety.

I know the labour was 1.7hrs. I don't know the exact cost of the bearing but it's about a few hundred bucks.

...comforting. I thought it would be one of those...$2,450.00 type deals. Thanks for conversing with me....this is has been more informative than any other inquiries I have made on this subject.

Now the intermittent check engine light.....

Check engine Lights!
Simple cause to more serious. Simple one gas cap not tight, should reset after 3 starting cycle. Next commonest cause. Mass air flow sensor malfunction. Third cause and the most expensive one plugged catalytic convetor. Been there done it all(under warranty :))
Ken Lam

...each time i get the email that you have responded i think..."dont read it, could be frightening" but here goes....

It is intermittent but it definitely is NOT going off every 3 starts. typically on 3-4 days then off 2. I thought it was gas cap as the rubber seal on cap is a little tired looking but I am now convinced it is something worse. Did the ford tech tell you anything else? why does the cat get clogged? any other symptoms?

Don't know why the cat get plugged but the dealer has replace quite a number of it. IMHO this may be related to oil consumption which most of the earlier ML do which mercedes refuse to admit. The symptoms was lost of power and rough handling due to engine misfire. The mass air flow sensor in my case was asymptomatic but it is a well known failure prone part. If the check engine light comes on it should register a code which a tech shoul be able to scan with an OBDII scanner.

Yep, Ken Lam knows his stuff..
 

I talked to my mechanic who told me it was the center bearing mount that needed to be replaced. He ordered the part and he estimates that it will cost $250-300 to repair. Whew, I was worried that it was the driveshaft! And as same as you, it should have failed 5000 miles ago, dammit. It's would be a real pain that it went 2 months before turning it in. Also, I had that engine light problem and sure enough after I secured the gas cap, it was ok, after 3 engine starts. I was worried initially when the light didn't go off immediately. Even scheduled an appointment with MB and worried that it might be the cat converter because I know how expensive everything is with MB. WHo would want to own an S-class out of warranty?! Thanks, guys.

...YES! not only is it the center bearing but thanks to this post (thanks Ken) I dragged my psuedo mechanic a$$ under the car and spotted the culprit! I kid you not, there was maybe 10% of the rubber seal left intact. Sprayed a TON of lithium grease in there and problem is (albeit i have only driven about 5 miles so far) solved. I know this a temp fix but I am giving it back. The dealer can have the truck, crappy bearing and all. Thanks again fellas.

I've never seen the mid-shaft bearing go out on one of these, I'll keep my eyes open for these now.
On the cats, I've only replaced noisy ones (where the matrix inside the cat has loosened up, it makes a rattling noise) and also I replaced one where one of the welds that holds the outer shell together actually cracked all the way aroundf the circumference of the shell. I would tend to believe this may happen if the cat is very hot (such as during a fast highway trip) and then the truck either is driven through a cold rain puddle or maybe taken through a car wash that has a chassis flush feature.
Then again, maybe it was just a crappy weld job.
I've never had a plugged cat, but then again, we've only replaced one ML engine due to high oil consumption.

Gilly