s.e.a.n.

Just happen to my 2009 C63, bought the car a few months ago currently at 62K miles. Car is out of warranty, however the dealer with working with MB to get it taken care of.

glennhl

We used Weibull analysis at work to determine the failure rate of poorly designed parts. Think of it as predicting when popcorn is going to pop. Some kernels pop early, most right in the middle, and some pop very late, but in the end, they are ALL going to pop.

And I bet that Mercedes has the Weibull curve plotted for these head bolt failures. I also bet they have weighed the option of paying for a retrofit versus covering the few that fail in the warranty period along with the good will partial coverage of cars bought new but outside of warranty.

hachiroku

i did a full factory coolant flush not to long ago to hopefully prolong the headbolts for a bit longer. planning to do a headstud job within the next 6 months.

117k here

Merc63

It's not the coolant, it's a design flaw and material flaw perhaps.

Jasonoff

pH of the coolant could accelerate the process though.

hachiroku

^ this

Merc63

Oh you think the coolant is going to eat away the metal? Ok I guess you have caustic acid as coolant lol.

Jasonoff

No, but corrode it, yes.

Additives in coolant are supposed to inhibit corrosion. It breaks down, coolant becomes less alkaline which can prohibit corrosion/rust.

Maybe I'm not understanding the HB issue, but aren't the failed bolts caused primarily by excessive corrosion?

If they were 404 SS with the same female head none of them would be failing.

I'd bet if the coolant was flushed as frequent as oil changes it would have prolonged failure.

Merc63

No it's a design flaw. The cross sectional has minimal material at the head.

Jasonoff

And corrosion. Have you seen any failed bolts that haven't been corroded?

hachiroku

^ this again. heat corrosion and torque all play a role in its failure. some more than others, otherwise these would have failed upon first time reving the engine out. design flaw nontheless

Case1906

3% failure rate according to this unscientific but interesting poll. Would love to see a larger sample size. Head bolt era guys should weigh in!

Vladds

So, I spent an hour tallying the failures from the forum, in a post on this thread, but then got denied posting due to inactivity and my research was lost when I tried to go back.


Anyway, here's what I was doing:


I wanted to update the failures for C63, so I gathered everything and found 13 members that reported failures of headbolts on C63.


What I came up with is:
We know when the new headbolts were implemented and how to look for those.
But:
We never saw a picture of a snapped but not rusted old school bolt.


If rust is a factor, what if Mercedes DID implemented anti-corrosion measures, pre-dating the new bolts implementation.


So I set out to refine the information at hand, by the manufacturing date, because in US, this can pre-date the year of the car, by as many as 2 years.
So I set out to guess by subtracting one year from the model of the car.




So I found a total of 13 reports of failure.


Of these only 3 were 2010 cars and of these only one posted that the car was made in the first quarter of 2009.


All other cars were 2008 (model 2009, guessing made in 2008).


Again, my research got deleted, cause I took to long to hit post.


Now, a factor that can skew researching my idea is that some people did not have the Mercedes antifreeze anymore, possibly negating the anti-corrosion measures.

Dogtag114

Bump?
Objectively a <3% failure right by this poll.
I have near 100k miles on the car, only wear item replacement in recent years and plan to drive this until one of us dies... hard to justify a $$$ preventive repair with such a low failure.

BLKROKT

116 poll responses out of north of 10,000 C63’s produced is statistically meaningless

Dogtag114

agree... are there real stats somewhere?

BLKROKT

Nope. But you can be 100% sure that a) as the PFL cars age and the defective headbolts prone to failure continue to rot in coolant, the failure rate will increase, and b) whatever the number is, it’s underreported due to poor knowledge, diagnosis and reporting of the root cause.

It’s not a question of “if” they will fail, it’s “when”.

e63_in_dfw

2009 E63 built in June 2008
Trouble showed-up between 105k and 110k miles
I was tormented with a low-coolant light two weeks in a row!
I found chocolate milk on dip stick.
I pulled passenger-side head: one bolt with broken head; one loose bolt.
I'll pull driver-side soon
I spent under $1500 for parts and special tools. Doing all the work myself.

kilramg

Adding to this thread. At 95k miles my ML63 just went up smoke. Had one CEL light a few months ago, Dealer did a leak down test no issue found. I took it back a couple of weeks later and asked Dealer to continue to investigate, they did a second leak down test....guess that is there only method to test for a coolant leak. Second test no issue found.
According to my wife all of a sudden the car started to shake/run rough, then within seconds the car was surround by white smoke and shutdown. Scared the kids and her as they thought the car was on fire, crazy.
I suspect the failure rate on these engines is much higher than 3%. Unfortunately, I another Mercedes the m156 engine.... kids don't even want to ride in that car now.

Dogtag114

Sorry to hear.

A few months ago I started to lose coolant... just a little... I topped it off twice in 2 months then took it in.

Two bolts were loose (stretched per tech) but none broken. I had them replace the head bolts and gaskets.

i can sleep at night now.

BiturboSF

Dodged a bullet! How many miles?

Dogtag114

98k

Yuille36

The statistics your gathering from this poll, actually paints a positive picture. It shows that the head bolt issue isn't a widespread as people make it out to be.
I know that this represents only a tiny percentage of C63 out there. I've owned three AMG's with the M156 engine, and neither of them suffered from head bolt issues.
But you always hear don't buy an E63, get a E55 and if you get a C63, make sure it's after 2012 because the head bolts have been changed, etc.....
I'm liking this poll

Jasonoff

The results are useless though because you can't update or remove your vote.

Case in point, Dogtag114 is one of the "40-60k miles" voters but is now actually a failed result.

asaud7

Adding to this thread. My C63 experienced head bolt failure in 2017. I had close to 90K on the odometer and started getting low coolant errors. Took the car immediately to my indie mechanic and told him it was headbolts. He's AMG certified and didn't believe me and thought it was something else. I told him to take the car for a test drive after refilling the coolant and he heard an unusual noise in the engine upon starting the vehicle. One head bolt was broken so the end result was a repair to the tune of $6, 275 (head bolts, lifters, cams, gaskets, motor mounts and spark plugs). My out of pocket expense was the $100 aftermarket warranty deductible and $150 for spark plugs.

I misread the thread and didn't select failure so the + - on the poll is likely me skewing the data--sorry.