IAWMohror

Hey all, have a 2011 350 4matic, have owned it for almost two years and have driven it about 40k miles since then, (has just under 170k total ... I think, I'd have to double check.) When purchased it had the GLK engine mount vibration but that was all that was wrong with it, it would vibrate at idle and then be glass smooth while driving at any given speed. I haven't gotten around to replacing them as it didn't affect anything other than idle vibration and it's never gotten worse or changed.

With that being said, a new, different vibration has arisen recently. This one starts at about 35mph and continues through to 45, but is almost non-existent between 37/38mph, and then is glass smooth again from 50-60~ and then an ever so slight, very minimal vibration when nearing 70. It changes with speed and is always the same at any given speed, (i.e. it's always the same amount/feel/type of vibration at 42mph and doesn't change; it's always really smooth at 55mph.) I'll note also that this only changes with speed and not engine rpm.

I've jacked it up and taken the wheels off to check wheel bearings, tie rods and ends, ball joints, suspension arms and struts, and everything is tight and unbroken. I had the front wheels balanced to see if that would help because it felt like it was coming from the front and if it did anything it was minimal, but I've been trying to diagnose it for a while and now I'm wondering if it's coming from the rear/center of the car. I'm taking the rears in to have them done but I want to be proactive in case that doesn't completely alleviate it either.

Has anyone had similar kinds of vibrations? My next stop was going to be the flex discs and/or center bearing or possibly changing out the diff fluids and/or doing a tranny flush?

GLKattitude

170K on milage huh. Put the car Safely on stands and get under it and grab the front driveshaft (Near the Rear of the shaft where it goes into the T-case) and shake if back-N-forth violently. If it has Any play at all in Any direction, then you have a bad U-joint inside the T-case. Search "Front Output Shaft Failure" for 4Matic MBs and you will find the fix. If you have No play at all, you could still have bad bearings inside the T-case causing vibrations/sounds.

IAWMohror

Well that sounds extremely unpleasant to fix, lol, ugh. Alright, I'll do that and see what happens.

Mmr1

Or it could be the u joints on the drive shaft . As mine was. Don’t let it break if it’s bad, a broken front u joint can destroy the transfer case-transmission and the differential . One guy here paid mb about 10,000 to fix his Glk valued at 10,000.00 . Stupidly mb didn’t put in a brace to hold the front driveshaft, from becoming a weapon, incase the u joint breaks. Imagine a 2’ long 15lb piece of metal driveshaft flying around going down the highway! Destruction!

IAWMohror

Replacing driveshaft u-joints sounds a lot better than anything that has to do with the transfer case. Looks like I'll be crawling underneath it tonight to check out some things.

Edit: I think you might mean the same thing as stated above? Are there traditional u-joints on the GLK driveshaft? I've tried searching for replacements but come up empty handed, the only thing similar is the front driveshaft with the u-joint attached that goes in the transfer case, (I believe), like GLKattitude mentioned.

Mmr1

The one outside the transfer case went bad on me, I was stuck in snow shifting back and forth. I got a whole new driveshaft because it damaged a flange that’s not replaceable. My mechanic said if I hadn’t damaged the piece on the drive shaft he could have replaced just the u joint. But I don’t know if it is sold that way. Look a FCP euro for prices. The Glk is not heavy duty. The driveshaft is difficult to replace, maybe 3 hours. Mb wanted like 3000$ an independent wanted 1200, I got it done for 500.

IAWMohror

I checked FCP and didn't find a u-joint at all on there.

John CC

Mercedes doesn't list the u-joint as a separate part. Sometimes this means it is "staked" in place and not held in with circlips. A drive shaft shop may or may not be able to replace it, but it's not a job for a DIY mechanic.

IAWMohror

Ah, thank you for that answer.

I've restored airplanes from the ground up and built race cars and there are a couple things I hate with all my being: diagnosing; obviously finding it before it breaks is way cheaper but I hate the 'hunt' with every fiber of my being. And after doing it for so many years I've slowly started to despise even the work, I can only say that I still do it myself because I don't want to pay someone else. All of this exacerbated when it's a daily driver and not a project or fun car.

calder-cay

I can relate. Been wrenching motorcycles and cars for fifty years. Just sold off all three motorcycles and three cars, and only have the GLK350 and Jeep Wrangler left. And it overwhelms me to think about working on those two

Mmr1

Another well thought out MB design, first there is no bracket to keep -hold in place, the front drive shaft from putting your Glk into the junkyard with 10,000$ in repairs , if the front Ujoint breaks, but if you need to replace a bad U joint you need to buy the whole driveshaft! MB will charge you about 3000$ for what would normally be only a few hundred $, on most drive trains . Really well thought out! Thanks MB. It’s things like this that ruin used Glk values.

GLKattitude

Well one has to get the whole "I have to go to the MB dealership blah blah" mentality out of their system. There are Indy repair shops in every town and tons of Youtube vids on how it fix this stuff if One is so inclined. Or..I guess you can just run around scared s#$tless about high repair bills I guess.

IAWMohror

Username checks out.

But yeah, replacing the front driveshaft doesn't seem bad at all and even a brand new cheap replacement is only $200-$300.

NYCGLK

Unfortunately front shaft replacement takes care of only one u-joint, the other one requires taking transfer case apart, which with 170k miles should be not far away.

But are you sure it's not wheels or tires? Are you on 19 or 20 inch tires? When I balanced my original 20 inch wheels the tire guys says none of them are straight, but they still balance. When I have certain wheels up front I get vibration. My friend also had weird vibrations on Q7 that was simply due to old tires.

Another thing is suspension bushings can be worn and causing vibrations at certain speeds. On my 911, front bushings would cause pretty bad vinbration at 60mph, I'm not sure who GLK's worn bushings affect things.

Lastly, failing transfer case produces more of noise/whine above 30mph than a vibration.

Curious what you will narrow it down to.

IAWMohror

Anyone know where to purchase the transfer case u-joint part?

GLKattitude

www.Maktrans.net will fix you up.

So you have driveshaft play at the t-case?

NYCGLK

probably a dealer item, unfortunately I don't have part number for it handy, but you can probably find online and then try online parts dealer that have reasonable prices vs. you local in store dealer.

IAWMohror

Thank you sir!
Not sure, no garage and there's snow everywhere so I'm checking it out this weekend. Thursday I'll have flex disc's, center bearing and front drive shaft here just in case. Might as well do all of it and not have to worry about any of it later. I have another car so if it is the t case u-joint it can stay parked until that arrives.

Odd Piggy

Check to see if your local dealer has an online parts order site. Mine does and parts prices are mostly the same as the online MB parts sites (25-60% discount). Plus since they’re local, parts can be picked up at the counter with no shipping.

Or you can try https://mbparts.mbusa.com which will direct you to the nearest dealer online order site.

GLKattitude

The problem with this, as far as the front output shaft housing IF it’s needed, is that Mercedes doesn’t even have a part number for this output shaft. If it goes bad, their solution is to sell you an entire transmission/ t-case.

IAWMohror

Welp, looks like that's it. I grabbed the shaft and there's no front to back or much play of any kind but that's a lot of u-joint dust.

calder-cay

So you're assuming the "dust" / rust is one or more u-joint bearings are worn away and that is the residue ... and yet there's no play ?

It'd be interesting to read what others think.

GLKattitude

Well you are there and we are not, but that looks pretty typical. Of there is no kind of play then this joint is not your problem.

Odd Piggy

I’m not familiar with the internal construction of this u-joint. But similar ones keep the bearings healthy by sealing lubricant inside. I think it was mentioned that this u-joint can’t be disassembled. Maybe double check for play with a pipe wrench on the shaft?

John CC

It's an off-the-shelf u-joint, sometimes called a cross joint, or cross u-joint. the problem is the way it's installed in the yokes. It's staked in place and most drive shaft shops won't touch it. If you're concerned, unbolt it from the flange and move it by hand, checking for smooth operation.