bhamg

The cause of head bolt failure looks increasingly to be a case of the metallurgy involved. The factory torquing procedure as described by Merc63 would seem to eliminate the chance of overtorquing. Certainly the torque value should put the head bolt well within its elastic limit. What else can it be?

Sincity

LOL....I'll probably be dead and wouldn't have to worry about it.

drawde

Might be a dumb question but does anyone have a PN for this head bolt or gasket? I recently took my car in for my 50k service, as i was driving home i had a CEL come on.. I took it in a couple days later, the CEL was gone but I asked them to check it anyway. they fixed/replaced and METAL SEAL and SCREW. This is a long shot but does this have to do with anything discussed above?

PN 156-141-04-80 METAL SEAL
PN 004-990-53-12 SCREW

^ from my invoice, covered under warranty

Also, it's an 09, ~50,0XX miles..

Merc63

Ya, I agree. They use a robot to torque it down, it would probably be 100% accurate. I think its a problem with the metal too.

Probably and intake manifold? That isn't a head gasket. Its a huge job.

bhamg

Metallurgy...that really would make this a time bomb that might eventually affect a large number of vehicles. These bolts would have been made by the supplier in a quantity (batch) sufficient for a large number of motors as well as for parts stock. While I'm not normally one to shout "recall" anytime something happens perhaps we might be edging towards that scenario.

DuaneC63

If the head bolts are the culprit, what is the possibility of replacing them with stronger bolts (assuming the factory bolts are flawed) in reverse order before a failure occures? Would the heads loose the seat with the head gasket or even worse cause a head to warp replacing one bolt at a time? I've not pulled a value cover off, can you even get to all the headbolts with the valve actuators and cams in place? If possible this would be a relatively less expensive form of preventative maintainance the waiting for a head bolt(s) to fail.

Merc63

Cams have to be removed. There is timing chains, 2 cams per bank and special tools required to hold the cams in place while they are removed. It's a huge job and would need to be done by someone familiar with these engines.

Im pretty sure the cams are in the way for a few of the head bolts... Sucks

Pit-Pony

Wiseteck say they have replacement bolts that are better.
How do they swap them out?

carjones

If the headbolts are the common denominator, there would be a compelling argument that some sort of assistance should be given. It would be prudent to collect all of the major repairs would and attempt to identify trends.
We may be then able to identify a certain manufacturing date or group that should be watched.

If this were 1980, I would doubt any manufacturer would bother worrying about this issue, but given this engine is used throughout the line in the high-end products I believe it a wise investment for the factory to warrenty these engines, and their repairs, for an extended period, if only to assure future customers of their confidence in these products.

bhamg

Does MBWorld allow a sticky for something like that? Or is the advertising relationship with MB too close?

Merc63

They remove your heads, install new head gaskets and new fasteners.

PTE

I posted this 9/10/2011 , but nobody paid much attention, Oh Well And good luck

So How does this motor get such awards & accolades ?? for being a ? best in class engineered motor. The 1st gen had no way the control the gear lash between the intake & Exhaust cams, got some gear noise !! The cams where made to a spec that is used through out the automotive industry ( Chilled ? Gray hi nodular cast Iron ) the buckets show wear not so much that the steel that was used , but the position of the cam offset was wrong & possible the lobe was not ground right to help spin the bucket. May You notice that most of the noise came from the left / drivers side valve cover. There was a time you could not get a replacement head for that side . Here is another surprise for you. have you seen were the Head of the cylinder head bolts on these motors ,just pop off. IT'S out there and coming your way soon, I call it , **** poor quality control from the vendor. No guards to protect the manufacture that uses these bolts. Get get this motor a little hot or some milage you got a Issue. And they built 1000s of these motors. The cylinder head is a manufacturing Issue within AMG. as Most issue have been corrected . To this point it , The head bolt issues still leaves some of you guy's cold and out on the street with a large bill . Cheers _PTEngineering

jvanbrecht

Please.. I'm the last one to complain about other peoples language abilities.. but that last comment was impossible to read....

PTE

No Wonder I didn't get many responses on BB. I have ADHD really bad some days.
Sorry & Thanks for the spell check
_PTEngineering

bhamg

From the ongoing reports of sudden coolant loss I figured the failure of the head bolt had to have been of a catastrophic nature, but it still boggles the mind to think the bolt heads just break off suddenly...not a comforting thought going forward.

GTibunny8v

Engines affected are M156 up to engine # 569xx 60 060658

Pit-Pony

Just curious, where do you find the engine number on the car?

PatSC23

Similar to my iPod dying the very morning of the first iPhone release!

Sincity

+1

Sincity

So, Mercedes DOES KNOW which ones are affected and choosing not to notify the owners at this point.

bhamg

This is interesting but not totally unexpected...at least now we have something more concrete to go on.

Pit-Pony

Found my engine number on my original window sticker which I kept.
My MY2012 is way more than 10,000 units over #060658

bhamg

Thanks for posting. Obviously I'm more than a little curious as to by what means you came by this info but for now I'll just say...I appreciate it!

PaulWdz

Where did you find the engine # on the window sticker?

Pit-Pony

In Canada, I'm sure it's the same sticker for the US, the number is right there near the top.