Bud Wilkinson

RIBE or RIRE was what I thought my head said.

Ingenieur

I don't think an old toothbrush and some WD40 on the head only (then dried with a clean rag) will impact testing

failure analysis will not help much in this case, they may tell it failed in tension, but not 'why'

metallurgical analysis won't help, I'm sure the bolt was built to sufficient spec

engineering analysis is the key
correct type of screw for this application?
destructive testing: set a test jig up with a similar joint and cycle it through a similar load: pre-tension then increase tension based on compression/combustion pressure seen by the joint, at the same frequency/rpm the engine operates
may not have to test to failure, just check the bolt to see if it is damaged/stretched beyong it's elastic limit

that would be very expensive and time consuming, and it may not fail without the corrosion, heat cycling, etc.

imho the best chance is to state there is an defect (material, design, etc., does not matter), when they refute that ask then why the change in the bolt design?

other avenues may be getting a bolt mfg to state that is the wrong head for the application, but good luck with that, lol

Bud Wilkinson

Agreed,
No testing without considerable expense will give an absolute answer.
No Vendor is likely to admit or state the bolt was either designed by their client wrong or manufactured incorrectly by them.
The question as to why the design change in the bolt head is the only valid avenue.

Bud Wilkinson

I went and looked at the damage and old parts today while we wait the week for the new parts order to come in from Germany.
I also got the MB TSB L101.30-P-051567 outlining the symptoms, failure and remedy. So it isn't like MB doesn't know the problem exists. Come On MB. Little help here. It is attached. A Google search for the document number will give many results linked to different years of cars from eautorepair.net which is a Mitchel DIY subscription service. Those of you with a Mitchel, Shopkey or other subscription can probably find it. Nothing shows up on that search from MB though.

motoman,
The broken and indeed all the head bolts are all completely circulated by coolant. i.e. the threads don't go through to the water jackets at the bottom, they actually are in the water jackets in the block with the threads at the bottom of the jacket some distance (i.e. more than 25mm or 1") from the head sealing surface.
I have over 20 years in the commercial automotive service industry and have never seen this design before.

I am linking some pictures of the rest of the bolts here and the broken end of the afflicted one too. It is clear that my engine had less corrosion than other pictures I have seen here. Also Mine don't seem to have the tilting seen in others. Both the head design and the lack of material around the bolts down to the threads in the water jackets were just a manor of saving weight. The broken bolt is clearly a stress fracture to me. One that took some time to propagate to a complete failure if you look at the bottom of the broken head picture there is a fracture that went for a time based on staining before the head popped off.
IMHO, an NAS style radius of material area from the head to the stem would likely have prevented these failures and still netted very acceptable weight savings and should have been incorporated in the new bolt design as well but I haven't seen them yet.

cabruce64

Hi,

I'm looking at a E63 , 2006 with 70,000 KM's on the clock but after reading this thread i'm paranoid about this head-bolt failure problem.

The thing is I haven't read of any incidents of this occuring on early m156's (e.g. 2006/2007).

Has anyone reported or heard of issues on these earlier builds. The car i'm looking at is engine 3506 off the line.

Also, has anyone in Australia had their head-bolts replaced (prior to failure) as pre-emptive maintenance outside their MB dealer? If so what was the parts and labour cost?

would appreciate any help with this!

Thanks

statepkt

Don't want to scare you....But my 07 had a head bolt fail. Check the earlier posts in this thread by me. Its not super common, but can happen. Best bet is to check your car against the affect engine batch codes

DuaneC63

Check the sticky on this. The range of engine numbers listed is there. As preventative maintenance this is an expensive item, but not as expensive as a new motor if you don't catch it in time and get hydro lock. This is not a simple job. US cost are about $5G to do it right depending on were you live. You can't just replace the bolts at the cams are in the way. You need a special tool to lock the cam chains in place. You should also replace the lifters with the newer design. If you're going to pull the top half of the engine you might as well check for cam wear (caused by the old design lifters) and do a value job on it since the heads are already off. Basically you end up with a new top half of the motor which will last you a very long time.

schmick325

I had an 06 ML63 and sold it recently as I had this issue always in the back of my mind. I have NOT seen on here anyone with an 06/07 M156 report a failure. They all seem to be 2008/2009 with around 30-40k miles on them.

Have a look at some threads on here about failures and you'll find a couple of people with 07 ML63 that did have something go wrong early in the piece. Whether is was broken headbolts or something else they didn't say.

I would never get the bolts swapped at an MB dealer. They would charge a horrendous amount. Find a good indi Benz shop.

cabruce64

Thanks for the reply!

Yeah I have read about the first 10 pages of this thread and a few others outside MBWorld but not a single 06 x63 incident.... makes you wonder. However I don't think I would be able to get it out of my mind :-) since I'm also looking at putting 80-100K KM's on the car over 3-4 years it makes the problem more REAL.

Extended warranties will probably only cover $5K on the drive train so would be OK if you are lucky enough to catch the problem early. Of course would be game-over with a hydro-lock and i'm also thinking about what will happen to resale value now that this is becoming 'common knowledge'; AMG=parachute (drop in value) but I think with this it will be more like an anvil aka road-runner.

Bud Wilkinson

cabruce,
You should check the sticky and the TSB that I posted a few posts back with my bolt pictures for affected engine range.
I might also add that there is no catching it early. The bolt/s either pop the head off or they don't. You can do like one here has done and replace the bolts one at a time with the studs or the updated MB bolts. Neither of these are recommended by MB. It has been successfully done though. In most cases once the bolt/s pop you are in for minimum new, head bolts, lifters (an updated part from SLS anyway), rod and main bearings, rod and main TTY bolts along with assorted gaskets and seals. Providing you didn't hydro lock a cyl and bend a rod. You may be hard pressed to find a place to do only the head gaskets and bolts if they know about the TSB recommendations too.
in my area it is $8500 - $10000 depending on parts from a very good independent here.

All in all still a wonderful car and once done it should be good to go for some time to come. Hopefully.

schmick325

If u Intend on doing that sort of mileage in the car I wouldn't worry about depreciation. I'd be more concerned about it being in the shop. It's not just the engine bolts you have to consider. The 06 models are at a stage now where the airmatic will be getting tired, also all the bushes in the suspension ect

These are very complex cars with eye watering parts prices in Australia.
The only way to justify owning it is to fly your parts in from the US (7-10 days) and get it serviced outside of MB dealers.

I went thru it all with my ML63.

cabruce64

Thanks Bud and Schmick,

Appreciate the comments and thoughts.

I need to think about this, it's just so disappointing that such an elegant engine design is flawed by such a simple ($10 bolt) problem and that Merc has done nothing.

The most disconcerting things about this is that it's not a matter of "IF" but "WHEN" it will occur.

Not sure if you've seen this article but it's a great read in terms of the M156 engine design and how it departs from contemporary Mercedes V8 design http://www.marcusfitzhugh.com/CLK/63.html

Ingenieur

what good is checking it?
they will only fix it if it fails and only then if under warranty or if negotiated

My perspective: it's just something to fret about until it never happens
OR
forget about it until it does
enjoy the car, nothing built by the hand of man is perfect

schmick325

You could turn it around into a positive and possibly use it as a negotiating tool in the purchase of the car.

There aren't a huge amount of 211 E63's here so they don't exactly sell like hot cakes.

If i were to own another car with an M156 engine it would be getting those Weistec studs fitted prior to delivery.

New water pump, thermostat, power steer pump, p/steer fluid tank and new Airmatic shocks all around and you have covered alot of the items that will go.

Bud Wilkinson

I agree with you, especially regarding the response from MB. Very disturbing indeed.
Knowing what I know now I would budget in the cost of one at a time bolt replacement on one of these engined cars and do it sooner than later. Schmick is right, at least eye watering, about parts prices on these cars for sure.
Rember it is always the $0.50 o-ring or $10.00 bolt in this case that can ruin a million dollar machine.
MB... My Wallet... My Mood

motoman

A local lab called me back after my initial inquiry a month back. Seems he's a gear head and interested in the headbolt issue. Don't know if this was salesmanship. Told him I'm waiting for my car to fail so I can take him a headbolt.

bhamg

Does he need a broken bolt or will corroded bolts suffice? I should have quite a few more of the latter in my possession soon.

motoman

Bud, I also read an ME paper assigning 15% of bolt failures to the area under the head which is a cold heading inspection point-the reason for the wedge tensile test sampling? I think I'll order 1 ea new style headbolt and buff it to look for logo and radius. motoman

Bud Wilkinson

Well I haven't heard from my shop if the parts have arrived yet to tell you of the radius or not question. Soon as I know I'll post. I would highly doubt if that was an included mod though.

motoman

The diesel guys are hot rodders and say a lot about head bolts as they increase boost. ARP is the standard.

Head gaskets are big topic, especially when considering one-by-one headbolt replacement. Most bloggers seem against this technique, and emphasize basics like level deck surface and head surface (.002"). A lot of their engines are high mileage.

We still need definitive guidance on: Must you retorque ARP studs once? Twice? A lot of tear down...but easier 'cause you just did it.

Ingenieur

that is an absolute falsehood
not all engines will eventually fail (due to these head screws)

if that is the case we would have seen hundreds of failures, and I can't even find a dozen

bhamg

I stopped updating the sticky a while ago re. individual cases but I think there are 17 confirmed on these pages, whether C63 or other 63 models. I know of 6 more at the store level that are not part of these forums. Still, that not a large number...yet.

Ingenieur

I counted all the failures on the forum
13 (built an excel spreadsheet)
but some are suspect: 2 were posted within 1 week of each other, and each member made only 1 post then disppeared, several others made the failure their 1st post, made a few more, then disappeared

there are 25,000 cars in the affected range (world wide: can't find anything on UK or German forums)
average faliure is 40k miles or so (20k to 73k is the range)
if all cars fail, and most built before 2010 would have 40k or so on them
so you'ld think at least 1/2 would have failed by now
12,000? no way

cabruce64

Yeah I wish it was that simple. I don't think posts in these forums are a good representation of actual failures world-wide for a few reasons.

1. How many users are registered on these forums? How many of those own x63's?

2. Sites like this are used by a very small minority of x63 drivers and so the stats here don't represent the wider population of x63 owners.

The fact that Mercedes is keeping quiet and haven't owned up to the root-cause of the problem (poor choice of bolt, head bolt sealant, corrosion or all three?) and the range of failures (mileage/time) are so wide and then its a case of 'when' not 'if' for those in the identified range ( zero to 60658) as far as i'm concerned.

It's taken between 3-6 years to surface in some cases published here 2006/7/8/9/10 models I'm sure these failures will continue to occur (based on the above) as the years go on, and most of them won't be published on this site or sites like it i'm afraid.

I looked at a E63 the other day that hadn't had its engine coolant (according to the logs) changed in 6 years with 80K km's on the clock - i wonder how long that car has before..... snap/crackle/pop.

motoman

This is a maddening problem. Even quadrupling the discussed failures is a small number , unfortunately probably acceptable in MB eyes.

Baffling also if 2-3 vendors may have produced batches, with galloping quality problems. Since the failures stretch from 2007-2010 , multiple vendors produced in parallel and stocked at AMG line totally mixed from square one? Not "just in time" scenario, so unlikely. Without a date code on the bolts MB and we are blind to detect pattern.

bhamg, I would like at least one unbroken headbolt and one broken (or breaking)with its head. I will make the trip . Rust ,corrosion is not a problem to a lab as they (apparently) prepare sample by cleaning , sectioning, polishing. This is prohibitively expensive , especially in view of the apparent randomness. Anyway it's worth the effort to get a quote . What's another shock in this story?