Hi all, I just bought a 2006 ML500 with 112K miles on it. I test drove it and inspected it what I thought was very closely. However, after having it for a few days, I've noticed a few serious issues. When I test drove it, I heard what I thought was just bad tire noise coming from the frontend, the tires were in terrible shape. I put new tires on it today and the "growling" noise is still there. So, I assume its either a wheel bearing or as I have read, the front diff has gone bad (most likely this, based on hundreds of others saying the same thing). Secondly, as I put it up on ramps to look underneath, I removed the plastic covers and saw a leak. At first I thought it was engine oil, but after closer inspection, I think its power steering fluid leaking from the steering rack (typical for this car I guess). I'm an engineer and have always done all my own maintenance (Hondas, Toyotas, GMs). but this is the first German, "luxury" car I have ever had. So, I have a few questions...

1. I refuse to pay $3-5K for a new diff at the dealership. I see several people selling bearing and seal kits on ebay, etc to rebuild the front diff. Has anyone here attempted that? How difficult is it to get the diff out of the vehicle? Any pointers or tips?

2. In reference to the steering rack. Have any of you guys changed your own steering rack? Was it a bear to get out of the vehicle? I once changed my steering rack on an Olds intrigue and I had to separate the subframe from the unibody and jack the unibody up several inches to get the necessary clearance to get the rack out of the vehicle. Other than that it was a relatively painless operation. Lots of room to get at it move around.

3. In reference to the steering rack, I see tons of third party auto parts stores sell rebuilt/remanufactured racks. Ranging from $300-$1000. Some have the EVO and some dont?? What is that? How do I know if my ML500 has speed sensitive steering? Can the EVO be removed from my original one (if it has it) and installed on the rebuilt one?

4. I see all the parts stores carry a rebuild kit for the rack. Would this be a better option? Just replace all the seals in it to stop the leaks? My car steers incredibly well. I would guess that none of the gears inside it are worn, it just leaks.

5. Power steering fluid...Do I really have to buy only M-B brand fluid? Is there not a brand from Advance or Napa that meets M-B's specifications?

Is there a place to get a M-B service manual or DVD?? I see online Chilton's has a yearly subscription for a few bucks. Has anyone used that?

Any info or pointers you guys can give to me would be much appreciated.

THANKS!!!!

 

Does the growling noise go away when you turn either way while driving? If so, its the wheel bearings.


Try checking the powersteering resivior o-ring that connects to the pump first. The fluid ends up dripping down all over the rack. Easy fix. And common problem.


Service manual access is subscription here


https://www.startekinfo.com/StarTek/Login.jsp

 

Unfortunately, the reservoir and that O-ring area is completely bone dry. It's definitely not leaking up high. It's definitely leaking from around the top of the head on the rack. It's leaking there and running down onto the EVO plug, and then down to the rubber boot on that side. The other half of the rack is completely dry too.

The growling noise does not go away when the wheel is turned. Its pretty much all the time. Also, I jacked up the front of the vehicle and checked for play in the wheel bearing and its really tight. No slop at all. Just how it should be.

So, do I have to replace the whole rack to fix that one leaky area? Or is there some kind of seal kit that I can use to fix that??

EDIT: That Star Tek info website...surely there has to be a better place to get info. That website is $3098 per year!!! Holy smokes!!

Isnt there some kind of manual or DVD?

 

You might be able to get new seals for the rack but you might be better off getting a rebuilt one..


Sounds like the growling could be the front diff... Maybe try checking the fluid in it but its probably the diff bearings.


I agree on the Startek.. I hate it. I was told that's the only service info. I just buy the one day subscription and print out as much as I can..


Did you buy the ML from a dealer? They might fix it if you just bought it.

 

Thanks. I will definitely do the one day star tek when the time is necessary.

I did buy it from a dealer, but not a fulltime MB dealer. The guy is more of a part time dealer. He buys a few trade-ins from local dealers, details them and then resells them. Not a volume dealer of any kind. I will relay to him how disappointed I am and try and get something in return. But I doubt it'll go over well, in this state, it is an AS-IS state. No warranties on used cars.

I have a strong suspicion that it is the front diff as well. Based on how its acting and my experience with diffs in the past.

How can I check the fluid level? Is there a weep plug or something at the proper level that the fluid is supposed to be at?? I didnt see much while looking around under there.

 

yup. there is a upper plug on the side that the fluid should be up to. I believe it is a metric allen head plug.

 

First off you did what I did, bought a 2006 ML without doing your research. Now your stuck with the POS. Mercedes just screwed everybody who bought these lemons and there is no better word to describe them. The day they left warranty MB through up their middle finger at the owners.
The steering rack pinion housings are faulty and need replace. You dont have to replace the whole rack but the axles and diff have to come out to get the rack out. I was quoted under a grand to do just that at an independent MB shop. When the diff is out get someone to replace the bearings. Did you drain the fluid and find metal shavings? Your best bet with this or any 2006 ml is to push it off a cliff and collect whatever your insurance will give you. I bought a new Toyota 4Runner and just use my ML350 as little as possible as an extra car because nobody will pay even wholesale book for it and its in real good shape. Sorry for being brutally honest.

 

I think the 2006 Ml is still a good truck still a Mercedes Benz I sold one last year on a used lot for something crazy financed like 18 grand on top of that the air suspension is the only thing that ever went wrong with it I did the job my self when my customer called back , its been over a year now and he hasn't had another problem with it I was reading these forums because im thinking of getting one myself , id like to know what happens with the power steering rack though does any one have an idea what causes these power steering rack leaks ? Or is it just the heavy front end and the exotic suspension set ups that are just prone to it ?

 

If its the top pinion seal is leaking they have a better housing that holds the new seal. Good luck my friend. My cost of ownership including depreciation has been equal to leasing a new one for the period. I could have been driving a bran new car same money. Also less trouble because the newer ones didnt have most of the major 2006 problems.

 

I could say the same thing about my s class I suppose , but I find myself defending these old broken down cars any ways , I guess its either a car payment or the repairs no way around it hope to hear that this repair goes will and no more problems best regaurds my friends !

 

2006 ML owner

 

I have begun the process of tearing down the car to get the differential out. It's actually going really easy. Less than 1.5 hours and all that's left is to unbolt the front driveshaft from the differential, then remove the three differential mounting bolts.

I have not taken the rack out yet (obviously, the diff is still in the way), however, I have looked at it pretty closely and I do believe it is leaking out of the top seal. You state that there is a new head unit or something that will better seal it?? May I ask, how you know this and where can I get this new head unit?

I have been looking all over the web for a rebuilt rack, and every website says they have them until you go to order one and then they're out. What I am contemplating doing is just removing the rack and then trying to open up the head unit and replace whatever seal is under that and replace the o-ring that are on the EVO speed sensitive valve, and putting it back in. The rack feels really good when driving, the steering is very precise so there is no wear internally, its just leaking a little out of the top. What is your opinion of just trying to replace a few seals and putting it back in?

Thanks for any assistance guys!

EDIT: ALso, just for kicks I took it to the M-B dealership here and let them examine it just to get a second opinion on what is wrong with it (for a $150 diagnostic fee) and they determined the same things I did. Leaky rear main seal, bad differential, and leaky steering rack and return hose. Total bill for fixing those???? Over $10,000!!! $5000+ for Diff, $3300+ for steering rack, and $1700+ for rear main seal. HAHA. I need to open a M-B garage, I could get rich at those prices. They must have gold plated tools.

 

WOW! 10 grand? WTF! I am glad you are doing it yourself. Keep us posted because I think my diff is starting to crap out..

 

Rockauto has the rack on the website


http://www.rockauto.com/catalog/raframecatalog.php

 

Hmm, that one wasnt there this morning. This morning they had an AC-Delco part there, it said in stock, then when I added it to my shopping cart and tried to purchase it, it told me it was no longer in stock and it removed it from my cart and from the website too.

However, this one from A1-Cardone (26-4022) is for models that dont include speed sensitive steering. Mine has speed sensitive steering and needs Cardone model 26-4008.

There are models on eBay rebuilt by Detroit Axle for around $450-500. I may look in to one of those. The models that dont include speed sensing steering, you can buy a rebuild kit for one of those for about $30 and just rebuild it yourself. They dont make rebuild kits for the racks that have speed sensing steering.

 

I had a Detroit Axle rebuilt rack in my Lexus LS400 and it lasted 3 days. Since I didnt even install it for a year after I first bought it they wanted me to send it to them on my dime to rebuild it again for me. Hence me being down 2 to 3 weeks and paying shipping twice. I said F this and bought a Cardone from RockAuto and was driving my car again in 4 days. Works good. I am very curious about your repairs so please keep posting along the way. Pictures are a big plus if you have the time. If it were me I would do a Cardone rebuilt rack. As of now I'm just seeping very little from the rack pinion seal and don't drive the car much anyway. I cant afford to bankroll my new 4 runner and dump thousands into my ML money pit also.

 

To be honest, I had such a hard time finding a decent rebuilt rack, I decided to not replace the rack. I'm in the same situation as you. Mine is only leaking a very, very small amount around the pinion seal as well. Also, I removed the front differential last night and when I did the front CV joint on the front driveshaft fell apart...the part that goes into the front differential yoke was seized in there. So, as I wrestled it out, it just came apart and the steel ***** in it fell out. So, I now have to buy another driveshaft, so that's basically my steering rack money. I ordered a new return power steering hose and some new o-rings. I was looking closely at the rack last night and I see that return hose is probably doing most of the leaking at its collar where it transitions from metal pipe to flex hose and also the plate where the two hoses attach to the rack. So, I'm hoping that by replacing the one leaky hose and by replacing the o-ring on the pressure hose that will eliminate the largest portion of my steering leaks. I'll then flush the entire system with german power steering oil. Hopefully that will last me for a long time then.





Steering rack. As you can see it's barely leaking.




Front driveshaft where the joint came apart while removing differntial.




Half of the front joint seized into the differntial pinion yoke.

 

Great comprehensive repair thread. Keep it up. Following.

 

Just as a follow up. I got the front diff out and opened her up. To be honest, for as much ruckus as it was raising, the bearings inside it felt really good, except one. It showed the telltale signs of failure that I believe everybody else's has. One carrier bearing was shot and the fluid was a little low, I believe, and the fluid had metal particles and shavings in it. So, all bearings must be replaced. the pinion bearings felt REALLY good. Not even the slightest bit of slop or play in them. But, since I have it open and I have it in my father's tool and die shop being rebuilt, might as well replace all the bearings/seals since I already bought them all. But, I'm pretty sure that if I wanted to be "cheap" I could have just replaced the two carrier bearings and those seals and been fine.

Here are two pictures of the carrier bearings, one bad and one good. One the one good one, it looks bad, but those are just oily finger smudges on the bearing rollers. They were pretty good shape.

Bearing still is pretty good, just my greasy finger smudges on the surface.




This bearing is completely shot. As you can see here, and the race was pretty worn as well. Typical M-B front diff problem...Polish Timken bearings and race.

 

I think you want a WIS - the Workshop Information System. Recent versions come bundled with the EPC (Electronic Parts Catalog). If you're unfamiliar with the WIS, you can read about it here. I've bought three over many years and they are fantastic. I've bought several copies because the software has gotten better (the old ones still work). Every service that your dealer can perform is detailed in the WIS because that is what U.S. Mercedes-Benz dealers use. The same is true about parts. My latest version is a 2012, which I bought from a forum member called Crazy Dave. Newer versions are available on ebay for as little as $17.

Lastly, this is a great thread. It's quite informative, even to those of us who don't own an ML.

 

thanks, I'll check in to those. What I ended up doing was going and purchasing a full year subscription to alldatadiy.com for the ML500. So far, its been pretty decent. It has all the special M-B service instructions, part numbers, TSB bulletins, etc. You just have to really dig around on it to find the specific set of instructions for the task you are trying to undertake. I believe it was about $26 for a year. But, it would be nice to have a permanent version on a disc.