wae PowerDork
5/23/22 7:38 a.m.

In reply to FJ40Jim :

I didn't have much trouble pulling die Kopfbedeckungen from mine back when I started on this process, if I recall.  As best as I can tell, I was the first one to open it up the first time and the other times were all after sealing with the special Mercedes Loctite.  I absolutely needed to wail on it with the slide hammer, but I didn't need to pry at all.  Maybe if you can get a corner, you could sneak some fishing line or something in there to try to cut the sealant?  That is pretty weird and frustrating that it's bad enough to leak but good enough to not come off.

wae PowerDork
5/23/22 9:26 a.m.

I started it up again this morning just so I could sit there and listen to it.  It's just glorious!  But, there is still work to be done, so let's buckle down and see what's up.

First of all, it is still leaking oil.  Not as rapidly as it was before, but that pan is going to have to come off, as I suspected.

Next up, we have a little problem with the Airmatic system.  I like this code:

"5507 - Suspension strut is implausible"

There were two fairly loud pops from the rear of the vehicle after the initial startup.  I figured it was the air suspension, but when it didn't just droop immediately I was hoping that maybe it was stuck in a sort of downward position and the pop was the strut going back up.  Yeah, I think both of the rears blew.  Before I buy parts, I'm going to get it back on the lift and take a look.  I thought the front strut had blown many moons ago and bought a replacement, but it turned out that the problem was actually just the seal on the air hose.  I suspect it's something more serious now, but I'm going to look first.  It looks like the Arnott replacements are under $250 each, so not the end of the world.

Okay, so the oil pan has to come off and the rear suspension needs to be fixed.  That's in addition to the core support needing to be put back in of course, and the other associated engine compartment bits need to be reattached.  I'm still missing a grille, but that's not completely critical.  The battery cover needs to be put back on.  And then we have the other codes from the engine:

  • 134900 - My code reader doesn't know what that means
  • 10BF00 - That's the cooling fan circuit showing open.  Makes sense, since the fan isn't re-installed yet.
  • 14E300 - O2 Sensor 1, bank 1 circuit open
  • 11D900 - The B 28/5 level dropped too low.  Whatever that sensor is.
  • 150E00 - B19 temp sensor shorted to ground
  • 124F00 - Y27/9 EGR faulty
  • 13CF00 - R9/6 Glow plug #6 open circuit

That should all be stuff that I'm mostly aware of.  The glow plug connector needs to be replaced, I'm aware of that.  The B19 is probably the exhaust gas temp sensor, which goes into the DPF, I think.  Same with the O2, I think.  The B 28/5 appears to be a pressure sensor, which I think is also part of the DPF system that is missing and capped off.  I just haven't put the cooling fan back in yet.  And the EGR valve sort of kind of came apart when I was trying to remove it way back when.  I had hoped that I got it back together "enough", but maybe I didn't.  I may need to track one of those down.  I'm sure that will be a cheap part.

The only part of that which particularly annoys me is the oil pan leak, but I am not really surprised by that.  I more-or-less expected that gobbing the Right Stuff around the seam would only work for a little while, if at all, so I was pretty resigned to having to get in there are fix that.  Now, granted, I haven't put it back up in the air to verify that is where the leak is coming from so it's entirely possible that it's coming from somewhere else, but if I were a bettin' man, I'd put my money on the pan.

FJ40Jim New Reader
5/23/22 11:34 a.m.


Bluetec code 134900: no CAN message was received from control unit NOx sensor upstream of SCR catalytic converter


The leaky valve cover gets weirder... Did eventually get the the VC removed without any further damage. Had a good gasket print across the front and all along the top rail. At the back and especially along the bottom rear, the goop had not been smashed flat. The 'dispenser marks' was still visible in the shmoo, indicating the VC had not been pulled down by the VC bolts in that area. All the bolt holes and the 2 dowel pin holes were clean to the bottom, so they were not bottomed out, holding the cover off the block. 

Gaskets have been scraped, VC is drip drying in the solvent tank. Sometime later today the VC will be dry fit to the head & torked down, then a feeler blade will go around the perimeter to verify there is no gap anywhere.

wae PowerDork
5/23/22 12:14 p.m.

In reply to FJ40Jim :

That would make sense.  My NOx sensor is currently in a box on top of the hydraulic press.  I guess it's not WiFi-enabled.

That is weird with the head cover.  Possible that the threads are damaged?  Or you managed to get some of the wrong bolts in there?

wae PowerDork
5/23/22 12:24 p.m.

Oh, I also gave myself a heart attack this morning when I was looking up sensors and such to verify what I had that was complaining.  For the front part of the exhaust, WIS has a picture that indicates a downpipe, then a cat, and then the DPF.  I was fairly certain that when I took the DPF off, it was just a single thing, but it's been so long I can't really remember.  So I started to have visions of Mercedes wanting to charge me $5000 for the catalytic converter that wouldn't be replaced anyway as part of the AEM. 

A whole bunch of searching and investigating later, though, and it does seem like my recollection is correct and that the only thing missing is the A164-490-75-36 DPF which gets replaced anyway.  To be fair, I think the O2 sensor is gone as well, and I know that the EGT and NOx sensors are in a box on the shelf.  So other than the O2 sensor, I'm not missing anything that they wouldn't be replacing anyway.  I realize I will regret asking this later, but how much could an O2 sensor be anyway?

wae PowerDork
5/23/22 12:29 p.m.

A little more research...  According to their site, this is what the AEM will do to my car:

So, I guess, even if I was missing my cat, they'd replace that.  Small win, here, is that it looks like they replace the EGR valve.  So I don't need to run one of those down.  I am a little bit pissed, though, that they're apparently replacing that stupid M55 motor.  And slightly pissed about the air duct, but I got that cheaply enough from the junkyard.

FJ40Jim New Reader
5/23/22 6:38 p.m.

I think to drive the truck would require the air duct with its dual MAF sensors, so it was kind of a necessity to get the recall done.

And yes, the first 'cat thing' (DPF& Diesel Oxidation Cat) and the second 'cat thing', (Selective Catalytic Reduction cat), are both gonna be replaced. (Former dealership warranty administrator talking) My only concern there is that the dealer is required to send back the failed part to complete the warranty claim. i.e. They don't get paid if there isn't a dead DPF, SCR, O2 sensors, etc to show M-B that the repairs were completed as described in the warranty/recall work procedure. M-B is gonna want those cats & ECUs to recycle. The dealer is under no obligation to do warranty work that the factory won't pay them to do. Hopefully the dealer will go to bat for you and get the repair authorized.


On my VC, spent some time this afternoon, installed the clean VC, torqued it down to the 30-ish and 50-ish in-lb stage, checked it all around, no gap anywhere. Pulled it off and reinstalled with ultra grey schmoo in a bead per the WIS, carefully followed the torque procedure, verified that it settled down onto the head 100% this time. Now it can sit until tomorrow while RTV cures, then the engine will be started & checked for oil leaks (again).


FJ40Jim New Reader
5/25/22 5:40 p.m.


A lengthy test drive last night showed no more oil leaks.

Previous test drive had shown some minor diesel fuel leaks at a couple of high pressure fittings. Torquing down the offending injector nuts seems to have cured those.

No new codes appeared and no CEL.


This coming weekend the travel trailer will be hitched to it and driven about 150 miles as a final test. Assuming it runs good, an appointment will be scheduled at the dealer for emissions recall.

wae PowerDork
5/28/22 12:34 a.m.

Great news!  Glad you were able to seal up that leak!


I was able to drop my oil pan tonight.  I'm not sure how to do it the way WIS says.  I already had the cooling fan out and I took off the bracket that's on the upper oil pan to move those lines out of the way.  Without doing that, I'm not sure how it's possible to sneak the pan out.


You can see where there is missing sealant in the back part:

I've got to get it all cleaned up and put back on now.

wae PowerDork
6/1/22 7:23 a.m.

In the last 3 days, I've had about 90 minutes of free time to spend at the shop and that included getting things opened up, stopping at the parts store for more gasket remover, finding spray paint for my wife to use, and turning on the CO2 tank for the kegerator.  I did, however, get my mom & dad's yardwork done as well as my own, worked a bingo, watched a parade, and spent time with the family, so it's hard to be upset about that!

All I really had time to do last night was to get the sealant cleaned off of the oil pan and about 75% of the sealant cleaned off of the upper oil pan.  I lowered the motor back into the chassis so I could put it up in the air to do that work and there's plenty of room to get around the edge.  The Permatex gasket remover is working pretty well to mostly dissolve the sealant; I've been gooping that foam on, letting it sit for 15-20 minutes, then scraping with a Formica sample chip and gently scrubbing with a brass brush.  The only real problem that I'm running in to is getting the gasket remover to flow against gravity onto the upper oil pan!  Fortunately, though, most of the sealant seems to have stuck to the lower pan which I can put on the bench and work with.

I won't really be able to get anything done today between work and after-work plans that are already made, but if things don't devolve at all over the work day today, I expect that I'll get the oil pan back on tomorrow some time.

Once the oil leak is sealed up, I need to find the coolant leak.  It's just absolutely spraying coolant and I think that one of the EGR valve coolant lines is still not connected all the way.  As soon as it's not spraying fluids, I'll get it put back on the insurance, get the plates turned back on, and I can try taking it for a real drive to see how it does.  While it's idling really well, my short excursions across the tiny parking lot are demonstrating that there's definitely some hesitation in the throttle.  It's acting like there's a bit of an air leak - when you give it more throttle it just bogs for a moment before coming back.  With the DPF gone, it's going to be in limp mode for sure, but I've driven it in limp before (hell, I towed a trailer with the car on it for about 150 miles in limp mode!) and while it's down on power, it would still drive smoothly.  So it could be the missing O2 sensor maybe.  Or it could be the EGR valve creating a vacuum leak because it looks a little bit like it's not bolted down all the way.  Knowing that they're going to replace a bunch of things, I don't want to go too far down the rabbit hole - I usually try to fix the things I know are wrong first to see if problems go away!

Something else that I saw in the computer that has me a little bit ticked off is that it's showing codes for the swirl valve motor again/still.  They're coming up as stored codes, they went away after I did the DTC clear, and then they came back as stored codes again.  I know the flaps are freely moving in the manifolds, I am almost certain that the motor is the right one, and I didn't see anything in the wiring that looked bad.  I'm sort of hoping that if they don't fix it as part of the AEM and if it's not covered as part of the extended warranty through the settlement, that they'll at least be able to tell me what the heck is going on with it.

FJ40Jim New Reader
6/1/22 9:26 p.m.

Wae, the dealer will do the emissions recall first. Once that is done, the 4yr emissions performance warranty begins. Anything that causes an emissions failure light (CEL) should be covered by that warranty. My opinion is the M55 and manifold flappers are emissions related, so should be covered if they are actually a problem.

My truck kept showing the DPF regen frequency code as a historic or stored code, even with a new DPF and a new engine. I cleared the codes and the DPF would come right back. All the DPF codes have disappeared now that it's been driven 300+ miles with no DPF errors. Maybe your M55 codes will also fade away after a number of restarts with no errors.


On our ML350, we towed the camper up north central Ohio this weekend. Weather was warm, but the air conditioned seats kept us comfy.laugh OTOH, the fuel economy sucked; 13MPG towing, 24MPG bobtail. Before the rebuild it would get 26-27 empty, 15 towing. On the plus side, it used no oil. Using a $12qt of oil every 300miles was about the same as getting 2MPG worse consumption. Maybe a new DPF and SCR cat will uncork some exhaust flow?

Unfortunately, I think the oil sump is leaking a little bit. I may be following in Wae's steps yet again. Will get it up on stands this week & find out.

wae PowerDork
6/3/22 6:07 a.m.

After having removed and re-installed the sump, I really hope yours isn't leaking.  It's not an impossible job, but it's not a ton of fun, either.

Before that, however, I figured out why my suspension strut is implausible:

The rear air springs have come out of their holes and are a bit bent over.  I was able to manipulate one of them back into position, but the other is more inflated.  I think I can disconnect the air lines up under the hood to deflate them so I can put them back and see if that gets things working correctly, but I'll worry about that when all the fluid leaks are squared away.  Worst case on that if I have to replace everything is about $160 per side for the air springs and $170 per side for the strut.  So as scary as people think the Airmatic system is, I can replace the whole rear suspension with Arnott lifetime warranty components for $670 after shipping and tax.

On to the oil pan...

I did the easy part first and cleaned the lower pan.  Cleaning the other surface on the upper pan was a real pain, though.  To make it a little bit easier, I put the engine back down on the mounts and raised the lift.  After a while, it was cleaned off:

Don't mind all the Right Stuff goo in the background.  One thing that I found was that the oil wanted to continue to seep down along the back there.  I got in there with a rag and tried to get as much of the oil off of that lip as I could and that seemed to keep it from coming over the lip and contaminating the sealing surface. 

I do not know how this can be done with the cooling fan in place.  Maybe I didn't have the engine lifted enough or something, but the only way I could get the pan to go in was to hold it almost vertically and lift it up and forward so that the bottom of the sump was against the radiator.  The sealing edge of the pan just barely cleared the oil level sensor apparatus.  Once the back end of the pan cleared the sway bar, I could rotate the whole assembly down and back to let it rest on the front diff.  I practiced that maneuver about 15 or 20 times to make sure I could do it without brushing the sealant against anything in some sort of automotive version of Operation.  I found a couple M6 carriage bolts that I cut the heads off of and lightly installed in two of the front bolt holes in the upper pan.  After putting the sealant on, I threaded the needle between the core support and the sway bar, swung the pan around, and used the headless bolts as a guide to get the pan to go up straight.  Then it was a matter of getting the first bolt installed to hold the pan up.  Even with the engine raised like that, it's still hard to get to all the bolts, especially with the torque wrench.  And especially when you're laying on the ground and have the legs of the engine hoist in your way.  It would have been much better to have suspended the engine in a manner that didn't require the hoist, but I didn't see the Harbor Freight equivalent of their special tool in stock when I was there and I couldn't make the 4x4 work very easily.  I did find that the load leveler on the engine hoist was pretty handy because you need to bring the front of the engine up as high as it will go and that required letting the back of the engine drop down a bit.  The other thing that I found problematic was that it requires so much hand strength to work the tube of sealant that by the time the bead was all the way around and it was time to lift the pan into place, my arms were basically shaking from exhaustion which added a layer of challenge to my Operation game.

After all of that, though, the oil pan is re-installed and torqued down to 124 or 125 inch pounds.  I don't think the sealant calls for a long cure time, but I decided to let it sit overnight before putting oil in it anyway.  I'm also not going to bother bolting the engine back down until I fill the crankcase and verify that it isn't leaking.

The other thing that I managed to screw up is that one of the coolant lines on the EGR valve is not even close to being attached.  I can see the flare on the hardline that is supposed to be under the hose and on the other side of the hose clamp, so that's definitely not right.  That hose is buried under a bunch of wiring harness, though, so of course it's going to be a pain to get to!

If those leaks are taken care of, then, and I get the rear springs in their pockets, then I should be ready to get scheduled with Mercedes.

wae PowerDork
6/3/22 11:23 a.m.

Sigh.  I thought it was going to hold the oil but as I was jockeying the engine around to put it back in place it started pouring oil out again.  Different place this time.  Here we go again I guess. 

Because using a berkeleying gasket like the rest of the world is so damned hard.

Dusterbd13-michael MegaDork
6/3/22 11:46 a.m.

So, why not use a roll of gasket material and make a gasket? 

Im asking. Never tried it, cause everything i work on has gaskets.

wae PowerDork
6/3/22 12:17 p.m.
Dusterbd13-michael said:

So, why not use a roll of gasket material and make a gasket? 

Im asking. Never tried it, cause everything i work on has gaskets.

I have been wondering the very same thing....

wae PowerDork
6/3/22 1:57 p.m.

Good news and bad news:  I'm getting pretty good at taking off the oil pan.

Looks like it just didn't seal there at all.  I think that when I tried using the slide hammer to remove the pan the first time I may have bent the lip out enough to keep it from mating up properly.

wae PowerDork
6/3/22 5:17 p.m.

Oil pan is back on.



I flattened it out, cleaned it all up, and put it back on.  This time I got the car raised up to the first notch on the lift so I had a little more room to work.  That, plus all the repetition, and this job is starting to be not that big of a deal.

And I kind of hate myself for saying that.

Time to go home, have some dinner, try to help my neighbor with her flooring project, and then I'll come back out tomorrow and put the oil in and see what we get.

Aaron_King PowerDork
6/4/22 6:05 p.m.

In reply to wae :

After living with our 06 R class you are right, Airmatic and Arnott make it cheap and easy. 

wae PowerDork
6/6/22 9:31 a.m.

I put oil in it 24 hours ago.  In the process, I was reminded why they say to disconnect the battery when you work on things.  The motor mount bolt is right next to the starter and I did a little accidental welding.  Oops.

Anyway, the lower pan to upper pan joint is dry after 24 hours.  No leaks from the seam.  The drain plug is leaking a little, but that just needs a new copper crush washer.  Time to continue moving forward!

The wife's 5's clutch is starting to slip a little so I need to get der Scheißwagen off the lift and in service so I can take the 5 out of service and put it on the lift.  I need to get that coolant hose on the EGR valve all the way, put the cooling fan back in, and then put all the insulation and sound deadening accoutrements back in place.

eastsideTim PowerDork
6/6/22 9:45 a.m.

Woohoo!  (at least on the oil pan sealing up). 

wae PowerDork
6/6/22 3:26 p.m.

Good news: I didn't fry anything when I grounded the starter the other day!  The core support is back on and I disconnected the height sensor on the rear right to try to convince Airmatic to start letting air out of that bag.

Now that it isn't leaking oil, though, it's spewing coolant.  Bother.

When I took the EGR off, I had to use a little more force than perhaps I should have.  The coolant is coming from between the EGR valve and the head so I assume that I banged up the EGR flange enough that it won't seal now.  Hopefully it's the EGR valve and not the head....  I wouldn't be that irritated about it except that they're going to put a new EGR on with the emissions work.  So it seems so stupid to go buy one at this point.  But maybe that's just what I have to do.

Patrick MegaDork
6/6/22 6:35 p.m.

Maybe just have to pull it and file it flat again?

wae PowerDork
6/6/22 7:26 p.m.

In reply to Patrick :

Yeah, good point.  That's definitely worth trying.

tester (Forum Supporter)
tester (Forum Supporter) Reader
6/6/22 8:16 p.m.

Ok, I am passing this along to the automation guys at work. 

"5507 - Suspension strut is implausible"


Best fault code description ever! 

FJ40Jim New Reader
6/8/22 11:40 a.m.

If the EGR valve is leaking coolant at the gasket, maybe R&R with some RTV to seal it enough to get to dealership for new EGR valve? You don't care if it functions as EGR, just as long as it holds coolant.


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