They Said it Can't be Fixed - A Journey to the Inside of a Mercedes Bluetec

With the encouragement of the forum, I went ahead and installed the other valve cover at the same meager 80in/lbs of torque. Parts have been getting cleaned here & there over the past couple weeks, so I went ahead and threw all the clean stuff at the engine last night. No in process pics, but this what it looks like with valve covers, injectors, front cover, oil pan, sump, rear seal, intakes, t-stat, oil filter, HPFP.

Still to do: try to reinstall engine wire harness, turbocharger, inlet pipe, vac pump....

In reply to FJ40Jim :

I feel it necessary to mention here that I think that whole oil-pan-sticking-out-the-front-of-the-engine just looks really goofy.  Sure, they had to do that because of the front axle and everything.  But it just looks so damned weird to have anything under the crank pulley.

wae said:

Unlike the other cam bearings, the front one has a groove machined into the bearing cap/valve cover.  That groove is essentially where the damage is on the cam and is represented by the green lines in that picture.  The oil comes up through that hole and into the groove in the valve cover/cap and then, I assume, flows around the rest of the journal from there.  99% of the damage to the cam is in the area that would be in that groove.  I assume that there were little bearing bits that came up from the #2 rod and got crammed into that bearing, causing the problem.

Since all the damage seems to be in that grooved section, I think I'm going to run with it as is.  There's nothing protruding from the cam journal any more and there's so much space in there anyway with the groove, I don't think that little bit is going to affect oil pressure.  Please correct me if I'm wrong or crazy here, but I think it's going to be alright.

Yes, sand/file/stone off any irregularities that are proud of the bearing surface, then clean, grease & assemble. It's not like we're gonna make it worse than M-B did.

wae said:

In reply to FJ40Jim :

I feel it necessary to mention here that I think that whole oil-pan-sticking-out-the-front-of-the-engine just looks really goofy.  Sure, they had to do that because of the front axle and everything.  But it just looks so damned weird to have anything under the crank pulley.

I noticed in the Jeep FSM that the oil pan is a conventional cast AL pan, all located underneath the engine. It's like M-B tries to make it difficult.

I would just like to state that timing an overhead cam engine is a pain in the butt.

Oy.  This is a real motherberkeleyer.  I'm not sure how I'm a half-tooth off here, but this is starting to get on my nerves.  I know this thing passed the "lock the cams then try to turn the crank" stretch test, but maybe there's more stretch in it than I thought.  I suppose I could get a new chain and see how that goes.

Finally!  All four cams are timed correctly!

But I've got the balance shaft one tooth off.

I had to put it down for a bit to have dinner with my parents, but I think I might have a hint.  Without the cam hold down tool, just using the little brackets, the cam is angled a bit when I pull the chain tight.  It's just about a half-a-tooth difference.

I'm going to break out the hold downs that I made and give it another try next time I can go over.

In reply to wae :

The crank and balancer gears are 18 teeth. If either one is off by a tooth, it translates to 20* of error, which would be visually obvious. In the pic above, the balancer is retarded by 3-4*, which is probably chain stretch.

The RH cams should also be retarded a little bit due to chain stretch, but in the pic they are advanced. Being off by 1 chain tooth at the cam is 10*. Maybe that cam needs backed up by one chain tooth, to take it from 5* advanced to 5* retarded.

These engines are known to drip oil from the turbo inlet hose and the breather hose. Unfortunately, M-B chose to place the active intake electric motor underneath the drippy area, leading to electric motor failure and a MIL. On a MB forum somebody posted this hack: put a roof over the motor. A piece of thin AL flashing is cut to cover the motor, tilting down toward the rear, to catch the oil and direct toward the rear of the vee, where there is a drain passage.

In reply to FJ40Jim :

Yes!  I love that idea!  I've got plenty of aluminum flashing that I can use for that.

I'm going to give it one more shot with the cam hold-down tool in place to see if it makes any difference, but I'm pretty sure I'm dealing with some stretch that is within tolerances, but enough to make it a little bit off.  I can either leave it as it is and just wait for it to stretch past the spec and see if the post-AEM warranty will cover it or I can replace it now.  Theoretically the timing chain is a part that's covered by that warranty, but I have concerns that if they get any sort of hint that I've cracked this nut open -- and they've got an official service record saying that they recommended a new engine and I declined the penalty -- I'll have a real fight on my hands.  Replacing it now isn't the worst idea in the world, but then I'm back to the whole master link problem where I need to go get some stupid tool that I'll use once.  Hopefully.  Or I buy the same kit you bought and just throw away the extra set of guides.  I don't seem to be able to find the chain itself in any format where it's a whole chain - even the OEM MB chain says that it's "with master link".

I am glad that you are taking this on, this has been a great thread. Yes it has scared me away from Bluetecs lolz, but god bless you.

Febi does list the continuous timing chain, PN 33902.

AutoHausAZ has it in stock for a reasonable price. Not saying you should buy it, just that it is available if needed.

In reply to FJ40Jim :

I don't know how the heck I missed that.  I swear I thought I looked there because I've ordered from them before - they had a much better price on the second set of mains cap bolts than idparts.

Ordering that up now.  For $124, I might as well just replace a part that is a known weak point on the engine.  I owe you a beer!

EDIT:  It appears that GRM advertiser and GRM Experience sponsor FCPEuro also carries that.  It's a couple dollars more, but includes free shipping.  So I'm going to try them first.

Given that it's coming via FedEx, and given that it's already had a shipment exception that I've personally never seen before, I don't know how much confidence I have in this, but theoretically I should have a new timing chain on Thursday.

So I found something really funny (in the I want to cry sense of "funny") last night.  When I bought this colossal hunk of Germanic excrement back in 2017, I took out a personal loan to cover the bulk of the cost.  Got a great interest rate through Lightstream and the process was pretty straightforward.  I can recommend using them if the need arises. 

Anyway, I make the last payment on April 15th of this year.

I wonder if I can have it running before I make the last payment.....

Amazingly, FedEx got the chain to me today.  It doesn't look that different:

But it took only a few minutes to get to this:

So, yeah.  I guess stretched chain.

Now for the front cover and valve covers.  And stuff.

Looking good now, WAE!

Time to start throwing stuff at the outside of the longblock.

It should look like this eventually, after many evenings of trying different bolts in different holes:

In reply to FJ40Jim :

I vaguely recall the engine looking something like that!

Hopefully I won't have to do too much of a bolt search.  Most of the bolts are bagged up.  I did discover, however, that the paint marker that I used will flake off of the plastic bags after a time, so I need to engage a little detective work from time to time.

The rest of tonight was spent scrubbing and cleaning.  I got the new front main seal installed and the timing cover is back on.  The manual says to replace the bolts with steel ones, but I re-used the aluminum ones.  I did take the locating pins out like they said to do, though.  The pulley is back on, but the crank bolt needs to be torqued.  I've got to come up with something to hold the engine in place while I put 200 ft lbs and then another 180 degrees on it.  Yikes.  The cam shaft brackets are torqued to spec, and the sliders and pins are all installed for the timing guides.  Tomorrow's project will be to finish cleaning up the valve covers so that they can go back on.  I also need to get some of the stupid oil that they require for this thing so I can fill the oil pump before putting the oil pan back on.

I was sort of joking about having it running by the 15th of April, but I just might be able to get my schedule to line up enough to make that happen.  Things that still need to be ordered, though, are:

• Alternator
• Intake tube / MAF sensors
• Swirl motor

I also need to come up with something to put in the exhaust where the DPF usually goes.  It'll be temporary - just enough to get it to the Mercedes dealer in limp mode so they can do the AEM.  Oh, and I'm going to need some of the special blue coolant to refill the system.

Isn't there a class action going on about these engines? Might pay for some of the parts...

In reply to Grunion :

There is a settlement, yes!  If you are a former owner, you needed to get a fork submitted with proof to Mercedes by May or June of last year to qualify for $900ish bucks.  That would be split among all former owners of a given car.  If you're a current owner, you need to take the vehicle to the Merc dealer and have the Authorized Emissions Modification performed.  That's a new updated DPF and some other parts.  Once you have proof of that, you send that to Merc by 10/21 of this year and they send you a check for $3500-$3600 minus anything they sent to previous owners for your car.  And they also give you a 48 month warranty on things like the DPF, the adBlue system, heads, timing, and some other stuff.

I've worked out the math and that check will cover my costs for the repair since my labor is "free".

If you could work on a rebuild of this engine full time, how long do you think it would take to do yourself if you didnt have to wait for parts? and how long would you estimate it would take for a "professional rebuild shop"?

In reply to BerryBeazly :

Assuming that I had the pile o' parts sitting there ready to go, I could probably get it done in 1.5-2 weeks.  So far the biggest time sink has been scrubbing parts to get all the junk out of it and trying to fit a stretched timing chain.  There's so much that can be wrong in there, though, and the parts prices can be so high, I can see why the shop and the dealer didn't want anything to do with rebuilding it.  There are quite a few parts that I would have just gone with new if we were talking regular engine prices.  But with the Mercedes Mark Up, I'm making decisions on a part-by-part basis.

In reply to wae :

80 hours seems like an insane amount of time to disassemble and reassemble something

I don't know how i could even get rid of my car with the problems it has. What a joke!

In reply to BerryBeazly :

That might be way longer than someone who knows what they're doing would need!  Someone who does this sort of thing for a living could probably cut that time significantly, but then they probably would have to front-load so many parts that it would be less risk and cheaper for them to just do a reman engine.

The biggest problem is the condition of the crank and block.  You just don't know what you're going to get until you open it up and having a crank welded and re-ground can take time.  It's entirely possible to open things up and determine that the block is trash and there aren't that many good used parts out there.  Same with the crank.  A new crank will run you about $2.5-3k and good used ones just don't exist.  I'd never trust a used engine unless I could hear it run and then do an oil analysis.  And then I'd tear it down and put in new bearings and timing parts at a minimum while cleaning the whole thing out. 

If I'm being completely honest with you, this is more of an ego project for me than anything else.  My hubris got me in to this mess and I'm counting on it to get me back out!  Anybody else see the problem with that?

wae said:

In reply to BerryBeazly :

If I'm being completely honest with you, this is more of an ego project for me than anything else.  My hubris got me in to this mess and I'm counting on it to get me back out!  Anybody else see the problem with that?

It's the challenge.  It keeps life interesting.  Totally worth it, at any cost.  In other words, "Hold my beer."