AMGtech's Crazy Diagnosis: Engine Porn Edition

"AMGtech - now with more recalls!" (amgtech)
10/27/2016 at 16:30 • Filed to: None

Now with more blue balls! Why blue balls you ask? Because it’s not a very exciting engine, not even an AMG. In fact it’s a diesel. With a whopping four explodey-holes. Although, this being oppo, you might prefer that to a raucous V8. This particular OM651 engine (2.1 liter) came in with a simple chirping noise from the serpentine belt. No big deal, right? RIGHT?! Boy was I wrong...

Backside of an upside down engine

Simple chirp. Let’s take the belt off and see if the pants fall down. Wait... No... See if the chirp goes away. So off the belt came. But the chirp remained the same. Fine. This particular engine has a crankshaft pulley with a one way roller/sprag clutch built into it. Similarly, the OM642 diesel engine has the same style set up on its alternator pulley, and those sometimes make noise. You may also remember from my last crazy diagnosis post that a crankshaft pulley sort of burned me before. I was not going to let that happen again. It’s also important to note that the front crank seal rides against the crankshaft itself, not the pulley as many engines are set up. So off comes the crank pulley. Fire her up. No dice. Chirp still there. What the hell?

Next step is to pull out the old ticker-listener, the trusty doctor’s tool, the handy dandy stethoscope! Time to pinpoint this noise and gather some basic information. First slowly rev the engine to see if the noise is rpm-dependent. Which it is, however it goes away above 1200rpm, or at least can no longer be heard over the sound of exploding dinosaur blood. Then pinpoint the noise to a specific location if possible. So a few of us took turns listening to various areas, top to bottom, side to side, front to back, since noises can easily be interpreted differently from one person to the next. Diagnosis by consensus FTW amirite? After messing around with that for what seemed like far too long we all agreed we could only hear the chirp from the front lower section of the engine, but couldn’t decide what the actual faulty component was.

So, logically, the next easiest step was to remove the front crank seal and run the engine as briefly as possible that way. Done. Noise still present. Believe it or not I had actually seen this exact problem, a squeaky crank seal, on a CLA a few months prior. Looks like it’s going to be an internal engine noise (like you didn’t see that coming). Time to get Mercedes involved, they need to be aware of this. Right now.

Anywho... Capture a sound file, take a few pictures, let them know what we’ve done so far, then wait for them to get back to us with what they want us to do next. We’ve already decided the engine needs to come out and get torn down, but that’s a drastic step and there’s always the possibility they know something we don’t, maybe they’ve seen this before. Finally they get back to us. They’ve never heard of something like this on this engine so they ask us to remove the front cover. The front cover on this engine is quite small because all of the timing components are on the back of the engine, which is another thing that makes this noise so strange, there’s almost nothing on the front that can cause any noise because there really isn’t anything there except for a main bearing. Maybe that’s it?

I’m a master decorator of metal cakes! Pretty black icing!

Pictured above is the front cover just before final reassembly. The black stripe is sealant, like RTV, but Mercedes own stuff and it’s seriously a gazillion times better than anything else I’ve ever used. That stuff is how the majority of components of the majority of our engines have been sealed for the last decade and it usually only leaks when someone messed up the application process while working on it. The front crank seal is pressed into the round bore and is maybe just over three inches in diameter.

So enough about sniffing glue. Front cover is off. Can’t see shit aside from one edge on the #1 main bearing. But I can tell it hasn’t spun, so that’s good. Can’t even see into the oil pan. That was a useless step, as it turned out. Oh well, had to be done.

Next they wanted me to detach the transmission from the engine just to make sure the noise was in fact in the engine and not just transferring through from somewhere else. Ugh. This was going to suck. Keep in mind, the transmission needed to remain connected electrically for the engine to start because it’s control unit, which is inside of the trans, takes part in the security “handshake” when attempting to start the vehicle. So I do that, very reluctantly I might add, with the starter very loosely mounted in a very nerve-wracking way because that’s the only way it would work.

BLANG BAM CRASH BLANG DING BING LOUD NOISES SPARKS FLYING FUCK ME WE’RE ALL GOING TO DIE KILL THE ENGINE MEOW!

Shit! Apparently the engine and trans were just off-center enough for the flywheel bolts to just barely touch the snout of the torque converter while rotating. Line it all up and hold everything in place with some scrap wood. Look it over, no damage, whew. Let’s try this again. Luckily this time no crazy noises. Oh, except for that chirp. I’m shocked. If you could see the look on my face you would know just how shocked I am. Guys, I’m shocked alright, just believe me. Really.

Finally after song and rain dance, the German gods bless the engine removal and tear down.

This particular engine cannot be mounted on the rear as you would with most engines because that is actually the timing cover. So you have to remove a ton of components, like the turbos. Dos turbos to be exact. All from the sides and use a special engine stand to mount to the sides of the block.

The turbos in question

Yes, there are two there, cute little things aren’t they?

That big plate in the top right, next to the lift post, is the timing case cover from the back of the engine block. One cool thing about this engine is the timing set up. As you may have noticed, it uses a lot of gears rather than chains or belts. It does have one chain, but it’s short for an overhead cam engine and only goes from the injection pump to the camshafts.

So many things had to come off I started running out of room to store them all.

Now back to your regularly scheduled programming. If I remember right from high school English class, this is where the orgasm kicks in. Or do they call it the climax? Whatever, same difference.

So engine is coming apart, oil pan off, timing cover off, valve cover off, windage trays off. Everything that matters is visible. Everything looks perfect. Rotate the engine by hand, but even with the injectors out and no compression building I can’t generate nearly enough speed to duplicate the noise. Damn it. Better keep taking things apart for a closer look. Here is where a little product-specific knowledge comes into play. This particular engine uses what is referred to as a Lanchester balancer to smooth out engine vibrations. It’s basically two counter-rotating balance shafts mounted near the crankshaft, actually just below and off to either side. These shafts run the length of the engine and have three roller bearings each; center and both ends. I had been suspecting one of these bearings for quite some time already, but as you can see they’re not very easy to access.

You can clearly see one of those shafts in this last picture. These shafts and their bearings are actually built into the main bearing cap assembly, which is all one big unit. Didn’t take a picture of that though, sorry, it by itself is classified and I’m not Edward Snowden. Or I forgot. You decide.

Unbolt and remove said main cap assembly, referred to as the Lanchester balancer assembly by ze Germans. Now That those shafts aren’t meshed with anything else they will spin freely. Rotating them over by hand I don’t feel anything wrong at all and there doesn’t seem to be any excessive play. Luckily the drive gears are bolted to these shafts. So I take my cordless, slap on the appropriate socket, and give ‘er hell. Sure enough, the driver’s side front roller bearing emits the exact chirp noise we’d been chasing all along.

Press out the old, replace all six bearings, both shafts, and both gears. Press the new ones in. Slap it all back together. And done. Noise gone. All that for a stupid little noise. But to be fair, these engines have been exceedingly reliable since they were released here in the US and no one that I’ve heard of has ever had to replace one or do more than replace fuel system components because it was filled with gas.

DISCUSSION (54)

RamblinRover Luxury-Yacht > AMGtech - now with more recalls!
10/26/2016 at 10:35

I’m thinking here that Benz kind of ought to have a “WTF!?” bounty if you come up with something they haven’t seen before.

E92M3 > AMGtech - now with more recalls!
10/26/2016 at 10:40

Just curious what the total damage is? Sounds like it’s covered under warranty, but assuming it wasn’t?

Flyboy is FAA certified insane > AMGtech - now with more recalls!
10/26/2016 at 10:53

Kinja'd!!!

Our school’s new Diamond aircraft have two Mercedes Diesels. 140hp each, runs on jet-a. They’re 2.0L and have a single turbo.

Kinja'd!!!

However, their larger, 7 seat model the DA62 I believe has the twin turbo model that you disassembled.

Jobjoris > AMGtech - now with more recalls!
10/26/2016 at 11:32

Awesome, couldn’t stop reading and I’m glad you found it. In other cases of course another solution would have worked.

Kinja'd!!!

BvdV - The Dutch Engineer > AMGtech - now with more recalls!
10/26/2016 at 11:44

That’s some serious diagnostic skill you’ve got there, goes along nicely with your writing skills!

DipodomysDeserti > AMGtech - now with more recalls!
10/26/2016 at 11:53

This is great stuff.

My bird IS the word > AMGtech - now with more recalls!
10/26/2016 at 12:00

So all of those insane parts are supposed to make it more reliable right? I am just confused as to why MB would subject anyone to this, even their own mechanics. I have to tear down an engine for the first time and it terrifies me. Unlike your situation, it’s only a 70s gm pushrod v8. I wouldn’t even try to change the glow plugs on that thing.

BobintheMtns > AMGtech - now with more recalls!
10/26/2016 at 12:23

Damn.... You should share this post with the car’s owner just to let them know how far you went to get it fixed-- Nice job.

AMGtech - now with more recalls! > RamblinRover Luxury-Yacht
10/26/2016 at 12:28

I love that idea.

AMGtech - now with more recalls! > E92M3
10/26/2016 at 12:29

Definitely warranty. Out of warranty, best guess, but honestly no idea, $7k.

AMGtech - now with more recalls! > My bird IS the word
10/26/2016 at 12:31

Lol yeah, honestly this is the most complicated engine I’ve ever reassembled. Not because of the engine itself, but all of the things that mount on it. It’s one hell of a puzzle. Don’t worry too much about that old pushrod thing, they’re super easy.

AMGtech - now with more recalls! > Jobjoris
10/26/2016 at 12:32

Worst case just throw a new engine at it.

AMGtech - now with more recalls! > BvdV - The Dutch Engineer
10/26/2016 at 12:32

Thanks!

AMGtech - now with more recalls! > BobintheMtns
10/26/2016 at 12:32

Lol he’s aware. And thanks.

RamblinRover Luxury-Yacht > AMGtech - now with more recalls!
10/26/2016 at 12:33

I mean, if they’re covering your diagnostic hours of Leonard Nimoy’s In Search Of, it’s a step in the right direction, but that’s not really an award as much as an “okay, yeah, that shouldn’t have happened”. A bounty would reward creative diagnostics and save them tens or hundreds of thousands in cost down the line.

AMGtech - now with more recalls! > RamblinRover Luxury-Yacht
10/26/2016 at 12:36

Honestly I’m probably going to lose my ass getting paid on this. There are very few repair documents published for this engine and no labor times for a lot of it. But my reassembly time is going to be seen as unrealisticly high. Why? Because the engine was apart for a month and a half waiting for main bolts. Remembering where everything goes is the worst kind of nightmare of this engine.

My bird IS the word > AMGtech - now with more recalls!
10/26/2016 at 12:55

I was under the impression that more moving parts = more points of failure. But what the hell do I know, I’m not an engineer. As for the almighty v8, I have a few good books (and the factory literature) so I should be alright.

AMGtech - now with more recalls! > My bird IS the word
10/26/2016 at 14:18

More parts definitely equals more potential failure points. But most of the extraneous crap is there to increase power, increase efficiency, decrease emissions. Typically it all works really well together. Building in reliability is probably an incredible engineering problem on top of everything else they have to worry about. But like I said in the main post, this engine isn’t known for having any problems.

uofime-2 > AMGtech - now with more recalls!
10/26/2016 at 15:49

I said to myself ‘I bet its the balance shafts” as soon as I saw those goofy gear driven things in the first picture and you’d said the diagnosis was weird haha

Good write up and a very interesting engine!

AMGtech - now with more recalls! > uofime-2
10/26/2016 at 15:50

Good call! And thanks.

shop-teacher > AMGtech - now with more recalls!
10/27/2016 at 16:38

Not so funny meow, is it?

And people wonder why German cars scare me ...

MonkeePuzzle > AMGtech - now with more recalls!
10/27/2016 at 16:46

I knew it was that too, yeah its the balloon shafts I said to everyone!

WilliamsSW > AMGtech - now with more recalls!
10/27/2016 at 16:53

Good stuff- I really enjoy reading how you think through these issues - keep em coming!

AMGtech - now with more recalls! > MonkeePuzzle
10/27/2016 at 16:53

Balloon shafts... te he he...

Immature sense of humor sometimes.

AMGtech - now with more recalls! > WilliamsSW
10/27/2016 at 16:54

Cool! I will! Don’t know how frequent they will be though.

RallyWrench > AMGtech - now with more recalls!
10/27/2016 at 16:54

So you’re saying, you’re going to set my country music award on fire a Mercedes has a balance shaft problem? I... did not see that coming.

Mercedes jokes aside, this is nuts. I can’t believe ze Germans actually instructed you to run the thing with the transmission off. Thanks for the in-depth info, much appreciated.

atfsgeoff > AMGtech - now with more recalls!
10/27/2016 at 16:59

Just looking at those piles of parts & accessories gave me the willies.

As an aside, that black RTV-like stuff is probably very similar to Permatex Right-Stuff. Elastomeric rubber gasket sealant that cures in minutes. I’ve never had anything leak where I used it. Permatex claims that it’s what most OEMs use for engine assembly these days.

MultiplaOrgasms > AMGtech - now with more recalls!
10/27/2016 at 17:03

Apart from injector failures.

LongbowMkII > AMGtech - now with more recalls!
10/27/2016 at 17:09

Instead of all those balance shafts, they should just make it an inline six.

The Lurktastic Opponaught > AMGtech - now with more recalls!
10/27/2016 at 17:11

Very cool post. Thanks!

WilliamsSW > AMGtech - now with more recalls!
10/27/2016 at 17:14

Great! For your sake, hopefully they’re not too frequent!

AMGtech - now with more recalls! > WilliamsSW
10/27/2016 at 17:20

No kidding.

AMGtech - now with more recalls! > LongbowMkII
10/27/2016 at 17:21

I’m okay with this. Even if it’s the same displacement.

AMGtech - now with more recalls! > MultiplaOrgasms
10/27/2016 at 17:23

Not in the US. We got a different, more refined, properly operating injection system right from the start.

LongbowMkII > AMGtech - now with more recalls!
10/27/2016 at 17:23

The world needs more small displacement high cylinder count engines.

AMGtech - now with more recalls! > atfsgeoff
10/27/2016 at 17:27

Similar yeah, but the texture, shininess and weight/thickness are totally different.

AMGtech - now with more recalls! > RallyWrench
10/27/2016 at 17:31

Lol totally different issue from 272 obviously (making this comment for people who read this later who don’t know the details of that fiasco as compared to this)

I know right?! I turned into a big drama queen and bitched like crazy about having to do that. And maybe secretly hoped their plan would backfire and cause more damage...

AMGtech - now with more recalls! > LongbowMkII
10/27/2016 at 17:31

1.6 liter V12 you say? Awesome!

Autofixation > AMGtech - now with more recalls!
10/27/2016 at 18:00

I love my stethoscope. It allowed me to verify that what I thought was a knocking rod was just a worn out timing belt tensioner.

KusabiSensei - Captain of the Toronto Maple Leafs > AMGtech - now with more recalls!
10/27/2016 at 18:24

This is making me miss the OM606.962 that I had at one point.

Although the rest of the car was late 90s DCX, so not exactly a ton of love there...

Saracen > AMGtech - now with more recalls!
10/27/2016 at 18:44

Fascinating!

So what is reliability like for the newer AMG engines? (particularly the new 4 liter)

RallyWrench > AMGtech - now with more recalls!
10/27/2016 at 18:52

Fiasco is right, we see probably 2-3 of those a year now, and I know of a bunch of cars throwing intermittent cam codes that the owners are just ignoring. I have yet to see a car “fixed” by the harness update and magnets. They might go a couple of months, but the codes always come back.

On this engine, man, I just can’t imagine the thought process that led them to that instruction! I mean, you pulled it off, but that could have been a disaster for a lesser tech. That would have been one sweet “I told you so” for you though.

AMGtech - now with more recalls! > KusabiSensei - Captain of the Toronto Maple Leafs
10/27/2016 at 19:15

Those certainly weren’t without their flaws though either. Great engine though.

AMGtech - now with more recalls! > Saracen
10/27/2016 at 19:22

Excellent actually. Biggest issues I see are software and fuel injectors (thanks Bosch ). Even those are getting to be less common. Despite the fact that we’re breaking AMG sales records pretty much every year, I’m probably working on fewer actual AMG issues than even just 3-4 years ago. Most common issues altogether are probably infotainment (software usually) or interior rattle related. Rattles on AMG’s are often because the suspension and tires are much stiffer than base cars. Throw a little felt tape or foam behind a panel, done.

AMGtech - now with more recalls! > RallyWrench
10/27/2016 at 19:53

I don’t know if you’re using an SDS or some aftermarket thing, but if you can read proprietary fault numbers then only a balance shaft/chain will fix 1200 and 1208. 0060, 0272, and a host of others will be fixed by magnets. There’s bulletins for both problems and I’ve never had one come back with the same faults after doing the appropriate repair per that bulletin/fault. But sometimes people will try to fix the balance shaft faults with magnets first, because it’s cheaper, but that will never work. And the harnesses are yet another issue, but most of those were fixed with the campaign as far as I know.

No kidding. They know me and are familiar with my work, so maybe that’s part of why they thought it was ok to suggest? I don’t know.

Saracen > AMGtech - now with more recalls!
10/27/2016 at 19:59

Wow, that’s great to know. Thanks!

RallyWrench > AMGtech - now with more recalls!
10/27/2016 at 20:25

Yeah, we have an SDS & Xentry setup. I’ve seen a couple of cars return 0060 after magnets and harnesses more than once, but those are the really intermittent ones that will pass a cam test every time in the shop, and they’ll go months sometimes without codes. One is an ‘08 E350, and from what I understand they’re supposed to have been fixed by then.

There are two types of balance shafts right? One sintered, one not? Our local dealer will get them in with the possibility of warranty, then kick it once it’s apart if it’s the “wrong” shaft, so the owner’s on the hook. That’s bitten a couple of customers of mine. The dealer told me they have to get magnets and harnesses first no matter what, but I pretty much just warn the client that it’s going to be a shaft if it’s 1200 or 1208.

AfromanGTO > AMGtech - now with more recalls!
10/27/2016 at 20:55

That’s crazy! It looks complex, but not too difficult to work on when you know what you’re doing.

I have a question for you. What do you think of my idea?

http://oppositelock.kinja.com/afromans-irrational-idea-of-the-day-mb-wagon-1788289657

AMGtech - now with more recalls! > RallyWrench
10/27/2016 at 22:29

Weird. I wonder if that one has an adjuster going bad. I’ve seen magnets go bad up to ‘10-’11. Or maybe a stretched chain? I don’t know, that’s strange that it keeps coming back. Oh oh oh, oil level and quality, but you’ve probably checked that. Has the engine been apart before?

That dealer sounds shady AF! I’ve never heard anything about two different shafts, aside from old and new. Just that the bulletin lists an engine serial number range, if it’s in its in, if it’s out the balance shaft should be the newer problem-free version. VMI and the bulletin should tell you before any work is done whether it’s covered or not. plus between those two bulletins, a short test should tell you if you’re looking at magnets or a shaft. Why harnesses? There’s a campaign for that, and if there’s no oil in the ME it’s not an issue. There should be no guessing with any of this, it’s all known and documented.

AMGtech - now with more recalls! > AfromanGTO
10/27/2016 at 22:46

That’s the problem! I have no idea what I’m doing!

RallyWrench > AMGtech - now with more recalls!
10/28/2016 at 00:22

That E350 has never been apart before to my knowledge, and it’s fastidiously maintained, one of our longest and best clients (they also have a sweet W124). We’ve done magnets and sensors on it, verified mechanical timing at the adjusters, the whole deal short of a shaft because the car is well outside the engine range. That one’s a mystery because we’ve never once caught it in the act, and there are never any driveability complaints, just a very intermittent MIL.

All the bulletin stuff makes sense, I’ve probably read and explained them to clients 20 times. The two possible shafts story, the dealer told my shop owner, and he relayed it to me maybe a year ago. That’s when they told him they have to take the car apart to ID the shaft, as if updated shafts were fitted within the bad range. Makes no damn sense, because I spend a ton of time in EPC and various service info, which the owner doesn’t, and never saw that. This was after we’d done one on a CLK that the dealer very clearly denied coverage on though it was within the range, then later went back to the client to say they’d have covered it. Thanks for the clarification.

We get a fair amount of business off the dealer’s back by the simple virtue of not being as expensive, and I think the service side may have resented that for a time. The place has been shady before, my shitbag ex-manager here landed there after the owner and I booted him, then got run out there too (then from the BMW dealer...then from another indy...). More recently there have been some positive hirings and personnel shakeups in parts and service, and they promoted a sharp guy who was a top tech to service director. They’ve since approached us positively, and know we’re on the same side, just trying to keep three-pointed stars on the road, so I’m optimistic.

AMGtech - now with more recalls! > RallyWrench
10/28/2016 at 01:04

Really strange. It would be fun to get my hands on. So you looked at the backs of the adjusters to make sure the little lines actually line up to ensure the adjusters haven’t rotated on themselves? Maybe a loose or poorly contacting ground? I’ve seen the ones on top of the valve covers cause timing faults when making our connections before. unlikely but possible. perhaps even a chafed wire somewhere. Poor pin fit at the ME causing internment poor connection?

I’m glad that dealer seems to be on the right track now. Hopefully it stays that way.

RallyWrench > AMGtech - now with more recalls!
10/28/2016 at 01:29

I haven’t looked at that one myself, it’s been since I came into the office. One of the guys has, said the marks were on. He’s replaced shafts and adjusters before so knows what to look for, and if one was off I’d expect a repeatable fault. We’ve had the VC’s off during all that and nothing changed so I don’t think those grounds are an issue. Haven’t gone as far as the ME yet, like I said we’ve never been able to duplicate the problem.

AMGtech - now with more recalls! > RallyWrench
10/28/2016 at 02:33

Yeah, figured as much. Just spit ballin’. As far as the adjusters go, on 271's at least, they will intermittently fail, sometimes out of time and sometimes in time.