In reply to wae :
I had a similar symptom on the rear suspension. The bag had a small leak in it that only presented itself when I parked on a particularly uneven surface that required it to extend more than normal. Once I replaced the rear bags, all was back to normal.
Still haven't had time to try to diagnose the front air system. What's weird is that I could hear it hissing while I was plugging the front right tire on Thursday, but I was on a schedule and didn't have time to try to locate the leak. I drove it to Bowling Green and stopped for food on the way back. We were in the store for about 10 minutes and by the time we came out both sides on the front were down almost all the way. After we got home Thursday afternoon, I let the car sit for two days and the front stayed pretty much right where it should be. Back when I first got the car, it blew out the o-ring on the air line for the front left strut, but that left the one side sitting low, not both. So I'm assuming that it's some common component which is probably the valve block. Maybe something in there is sticking or something?
In other news, I was on my way to pick up my daughter from visiting a friend last night when I lost the power steering. Not long after that, of course, the dash informed me that the charging system wasn't working and I was watching the engine temps start to climb slowly. Fortunately, I was close to home still, so I muscled it back. Without power steering, that vehicle is basically impossible to turn at anything under about 5mph. Good thing I have a spare belt in the back, but it kind of sucks that I only get about 20k miles out of one.
The shortened belt life could be a bad OAD on the alternator, or a bad crank damper or a bad tensioner. These parts seem trivial, but they are designed into the belt drive system. When one component fails, other things start to fail.
wae said:.... Back when I first got the car, it blew out the o-ring on the air line for the front left strut, but that left the one side sitting low, not both. So I'm assuming that it's some common component which is probably the valve block. Maybe something in there is sticking or something?
As I said earlier, the valveblock is one of the few possible sources for leaks, so I think that is a good place to start. It is an electrical-pnumatic valve, and as I understand there is nothing but the nylon hose between the valveblock and the strut. A leak upstreams the valveblock should not lead to a leak on the strut.
It is a simple job to replace the valveblock, at least on the ML. Here is a picture of my old.
In other news, I was on my way to pick up my daughter from visiting a friend last night when I lost the power steering. Not long after that, of course, the dash informed me that the charging system wasn't working and I was watching the engine temps start to climb slowly.
..........
Good thing I have a spare belt in the back, but it kind of sucks that I only get about 20k miles out of one.
One thing I didn`t undetstand when you had your motor out and in molecules is why you did not replace all serviceparts relating to the belt then. When I worked on my engin now, I replaced the belt, the belt tentioner, the waterpump, the generator pulley, and the two small wheels (don`t know what you call them) when I first where in there. According to my car mechanic friend all of those parts are serviceparts, and a broken generator pulley alone can do great harm to the engine in worst case.
I wouldn't rule out the harmonic balancer being faulty in some way, but I always assumed that the issue was that there's a bit of an oil leak from somewhere on the front of the engine and it seems to keep the belt wet. The alternator was replaced about 40k miles ago, it got new idler pulleys around 50k miles ago, and I put a new tensioner on it when I prophylactically replaced the belt 21k miles ago. Since a new belt is about $30 from Rock Auto, I just keep a fresh one in the back and usually drive around with the 12-pt 17mm socket and a ratchet, just in case. When I did the last oil change I considered swapping the belt, but clearly I decided against that.
The main reason that I didn't go through and replace things like that was to avoid the "while I'm in here" spiral. I could have used all new pistons and rods, and I could have replaced all the lifters, I could have put new cams in and used all new timing sprockets, I could have replaced all the valves with new ones, replaced the water pump, put in a new vacuum pump, gotten a new HPFP, etc etc etc, but once I started doing that, I'm not sure where it would have stopped and it would have gotten crazy expensive. So my goal was to replace what needed to be replaced and re-use what could be reused and try to get the vehicle back on the road spending as close to the amount I was going to get from the emissions cheating settlement as possible. The dollar value of the rebuild basically broke even with the settlement, so I'd consider that a win. The settlement's warranty also got me a new turbocharger, one of the swirl motor sensors, a new AdBlue tank/heater/sender, and a couple other small repairs.
I bought it in early 2017, the motor grenaded in late 2018, so 1.5 years and 30k miles in the first run. I got it back on the road in July of 2022, so a total of 4ish years and 80k miles out of it so far. I'm not tremendously unhappy with that.
If it's easy to find on the ML, it should be in about the same place on the GL. It looks like this is what I'm dealing with:
I suppose maybe it's possible that the line to or from the air tank in the back might be a problem, but I don't see how that would cause both sides to drop. And I was absolutely hearing hissing from the front of the vehicle. Near where that valve block appears to be located. And, yeah, that hissing noise was after I had removed the valve core and let all of the air out of the tire! I do wish they had a slightly clearer diagram of the Airmatic system, though, so I could see if there was another spot that might be common between both sides in the front, but my thought is that I can park the vehicle in the same spot that I had it when I was plugging the tire and get it to leak and I can spray what Mercedes calls "leak detection fluid" and normal people call "soapy water" on everything until I find the bubbles.
Got the belt changed out this morning. Interestingly, it didn't come all the way apart:
Looks like it basically came apart in the center and split.
You got an Adam belt!
It's missing a rib...
Not long after we got out R class the right side of the car would sink to the ground over night, not having a lot of time then I took it to an Indi MB shop and they found that one of the nylon lines from the compressor had rubbed on the bumper support, gotten a hole in it, The compressor tried to compensate for the hole and burned up.
wae said:The main reason that I didn't go through and replace things like that was to avoid the "while I'm in here" spiral. I could have used all new pistons and rods, and I could have replaced all the lifters, I could have put new cams in and used all new timing sprockets, I could have replaced all the valves with new ones, replaced the water pump, put in a new vacuum pump, gotten a new HPFP, etc etc etc, but once I started doing that, I'm not sure where it would have stopped and it would have gotten crazy expensive. So my goal was to replace what needed to be replaced
That is totally understandable, I would probably have done the same reasoning.
If it's easy to find on the ML, it should be in about the same place on the GL.
Here is a video of that job on an ML.
Looks like it has the same location on the GL.
Just remember to support all wheels. When you pull out the nylon hoses, the struts will collapse. (How do I know 
)
I suppose maybe it's possible that the line to or from the air tank in the back might be a problem, but I don't see how that would cause both sides to drop. And I was absolutely hearing hissing from the front of the vehicle. Near where that valve block appears to be located.
....
I do wish they had a slightly clearer diagram of the Airmatic system, though, so I could see if there was another spot
Correct me if I am wrong, but as I understand it, the thin nylon hoses goes directly from the valveblock to the struts. That should give you this potentional places for leaks:
However, if the symptom is that it leaks when you park the car in a certain angel, I don`t think the problem is the valvebloc itself. Then someting is leaking when twisted.
The good news is that it is finally completely broken. The compressor just goes and goes, but pretty much never lifts the suspension. So now I just need to get five seconds to rub together to take the thing over to the shop, get it up in the air, and figure out where the leak is originating.
Finally time to get it into the shop. Let's see what we have:
Let's get it up in the air and take a peek!
Hmm, this is probably the first clue. Looks like these orings were supposed to be keeping the air in the airbag
The line to the air filter is broken. And the bushings seem a little loose.
After running the tests in DAS, it appears that the compressor is maxing out at 7 bar. It's supposed to be quite a bit higher than that - I've been told that if you can hold your thumb over the compressor outlet while it runs, the compressor is bad and I've done exactly that. The front right strut as pictured above is also clearly not holding air - while the other bags on the car show around 6 or 7 bar of pressure, that one shows atmospheric. That's the only one I've never replaced and as far as I know, it's original to the car. I can't be too upset about having to replace a strut after 177,500 miles. It is not outside the realm of possibility that I would also need to replace the valve block, however I sprayed it all over with soapy water and didn't see any bubbles.
Once I have the new compressor and strut in place, I'll be able to run through the tests again and check the valve block. It's really not that hateful to access with the car on the lift, so I don't mind holding off on spending $250. I think the worst part of the job will be dealing with Satan's Special Wheel Holders. Or as we call them in America: Lug bolts.
Oh! And I almost forgot... While I had my head up in the wheel well with the liner removed, I can see a spot that seems especially covered in oil on the engine. I'm going to see about cleaning that up real well to get a better idea of where the oil is coming from to make a determination as to if I want to fix it or not.
Today was Parts Day - the new strut, the compressor, and the mounts all arrived on my doorstep this afternoon. The last time I did a strut, there was a Honda sitting on my lift, so I had to do it in the dark in my driveway and wound up having to go back over to the shop to get tools halfway through the job. This time, however, I had plenty of light, I could put the vehicle exactly where I needed it, and the farthest I had to go for tools was about 15 feet. Hell, I had to walk about 6 or 7 times that distance to the fridge and back to get a beer!
Getting the old compressor out was a little bit of a pain. A 12mm stubby wrench got the air line removed from the back and then some fiddling had to happen to unplug the electrics. There are 3 10mm nuts that hold the compressor up - 1 in the back and 2 in the front. Well, I guess, it's more like one on the left side and two on the right, if we're orienting ourselves with the car.
The old compressor:
Can you believe what garbage that air suspension is. Only 177,500 miles out of that part. Air suspension is just so awful.
It look a little fiddling, but the new compressor went in pretty easily overall.
Next up, the old strut had to come out. In order to get it out, the strut tower bar needs to be removed and then it's a simple-ish matter of popping off the three 13mm nuts on the top, pulling the air line with a 10mm open end wrench, popping off the 21mm nut for the sway bar endlink, popping off the upper ball joint, and then getting the 24mm control arm bolt out of the bottom of the strut.
That 24mm nut is a real bear, though. My impact socket didn't survive the attempt.
Push down the lower control arm, slide the strut out, and then reverse the process to get the new one in place. Don't mind that the ball joint isn't bolted up yet - I caught that before I was finished and got it snugged up,.
I fired up DAS, reset the lifetime counter on the compressor, and ran through some tests. Everything looked good.
With the car up in the air, I went ahead and pressurized all the bags and then set it down to see if the vehicle would return to normal height and stay there:
Huzzah!
All told, it was only about 2 hours' worth of work to get everything swapped out and buttoned back up. The best part of doing this on the lift is that I could position the hub at the exact right height to be able to easily thread the wheel bolts in without having to also hold up the 75 pounds' worth of wheel and tire. Not a very difficult repair - I would say the hardest part was breaking the control arm bolt loose, but even that wasn't really hard, it just needed a little oompf to get it started.
I needed to get the suspension fixed last night because I wanted to take der Schießwagen for a couple hundred mile road trip today to do a college visit with my youngest. Apparently I got everything hooked up correctly because nothing fell off on the highway, so that's a good thing. Previous to this repair, there was always a rattling noise at highway speeds that I suspected was some bit of trim or undertray that was loose and blowing around. When it was making the noise I would think that I needed to get the car up on the lift and figure out what was causing that because it was really annoying. When I wasn't at highway speeds I couldn't hear the noise, so I forgot it existed. But the good news is that about halfway there today it occurred to me that it wasn't making that noise anymore. So I don't know what it was that was banging around, but apparently it was something that I took off and put back on last night.
I am impressed by your ability to maintain your MB no matter what problems arise wae 
Haven`t been logged in here for a while, but can inform that I did a rather big job on my old ML earlier this winter. All faulty codes are now gone, and the engine runs smoothly. But I have a little concern about oil consumption...
In reply to Komodo :
What kind of oil consumption rate are you seeing?
In reply to wae :
I am not quite sure yet. The car is bearly in use. I normally drive the Leaf in all daily errands, only drive the ML when I need to pull a trailer, or need more space. But the first time I checked the oil level after the repair I had to add nearly a liter, and I had not driven many kilometeres then. After that I have not checked the oil level (will check afterwords...). Have no clue how many kilometeres I have driven either, but that I also can check afterwords.
However. One day I drove home from the boatyard, and a fried drove behind me. I noticed that it was a significant amount of smoke behind the car. Acctually, it was so bad that my friend called me up and commented that he saw the smoke, but not the car... But the next time I used the car, the smoke was gone. I settled with the explanation that the (damned) car had started some kind of regeneration of the DPF or some thing. Is that possible? I did not think much more about it before I checked the oil level. I don`t know, but I don`t have the best gut feeling about this ...
I have never seen any smoke come out the exhaust on mine. I do not know much about the DPF regen process, so I don't know that if some sort of failure of that process could cause smoke, but I know that it shouldn't do that as part of normal operation. That sounds like some pretty heavy oil usage, though. One of the "known problems" is that the rings get stuck and they start to burn a significant amount of oil. If it were a normal engine, I'd advocate pouring a bunch of ATF or MMO in the cylinder to try to break the rings loose, but I'm not sure how that would react with the DPF.
The engine I rebuilt had severely coked pistons & rings. I don't think MMO or any other 'cure in a can' would fix it.
Shait, that ditn`t look good!
What is MMO?
By the way, saw on the news the other day that your president bragged about that the gasoline price now was down to 1,98 USD/gallon (is that correct?). That is in the lower range of what we pay for one liter
Komodo said:Shait, that ditn`t look good!
What is MMO?
By the way, saw on the news the other day that your president bragged about that the gasoline price now was down to 1,98 USD/gallon (is that correct?). That is in the lower range of what we pay for one liter
No, he's lying/delusional/misinformed by staffers. Pick one.
Lowest average gas price in the US at the time of his speech was $2.70/gallon, in Mississippi and Tennessee.
Returning to our scheduled content, I'm glad.to see this vehicle is one that keeps on giving.
In reply to Komodo :
MMO is Marvel Mystery Oil. One of those fix-in-a-bottle products that can actually do some good. I agree that it would probably be asking a lot of something like that or ATF to loosen up the rings, but it's one of those things that's a lot cheaper than tearing the engine down, so you might as well try. But in the case of the OM642, I don't know what that would do to the DPF.
While driving home from Mid-Oh this past Mon, the dreaded "check the adblue level" warning popped up on the info screen. Supposedly this means there's only 10 starts left before it goes to limp mode. After getting home, parking the trailer, emptying the back of the truck to access the piss tank, realizing there's only a half gallon on the shelf, running to Menards for 7.5 gals... It took 5.2 gallons of DEF to fill completely. Surprisingly, it has only been 6k miles since it was last filled up. DEF is being consumed at a far faster rate, now that the "emission update" (recall to enable the emission system) has been performed.
Otherwise this trip was uneventful, no ABS or Ck Engine lights on dash, 14mpg towing a boxy RV.
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