Pierre-CT

I am very interested in purchasing a CLK 63 AMG but am anxious to avoid some of the known problems.

Of particular concern are the headbolt and valve lifter problems with the M156 engine:

I understand that most early vehicles had these parts retrofitted under warranty, so I would just need to check service records to make sure that this was done. Is this a valid assumption?

I also understand that, from a certain point, MB started installing the new and improved parts such that they would not have been replaced - from what engine number (or other identifying number) did this occur?

I want to screen out cars that were fitted with the bad parts, and did not have them replaced.

I've also read about transmission problems in early vehicles - is this true and, if so, how do I screen out problems here (from what engine number onward was the problem resolved)?

Are there any other major defects that I should (and can) screen for when considering cars?

Thanks!

Chadzu

The factory didn't change the parts until 2011 model year cars. Mercedes also didn't fix the early cars unless they failed. I would not assume the car was repaired. Most never have had a problem. Very few clk's have the m156 motor, so for motor specific questions you may have better luck asking in the c,e,s class forums.

Barry O

None of the CLK 63 cars had the deadbolts replaced unless they failed while under warranty. I also read about a few owners that got some"goodwill" help from MBUSA and the dealer, however I doubt they would do that now as the last of the CLK 63's were 2008. I had all the deadbolts pre-emptively replaced on my car and it was just shy of $6,000.00. I told that is a deal versus what you pay if the engine fails or worst case hydro-locks! Good luck they are great cars and absolute beasts.

Pierre-CT

This is very helpful, albeit disappointing feedback, thank you! It appears I was given overly optimistic information regarding the extent to which these engine problems were addressed by MB.

In essence, any purchaser of a CLK 63 AMG at this point has two options:

Pay the purchase price, plus $6-8k to replace the headbolts and valve lifter which, left unattended, could result in catastrophic engine failure.

OR

Take your chances and hope that your car's parts are not defective; if you're lucky, great, if not you could face a repair bill that comes close to equaling the car's value.

Is there any indication that the problem doesn't occur past a certain mileage? E.g. if the headbolts or valve lifters are going to fail, they will have done so by 50k miles. I'm trying to stay optmistic :-)

I wonder if AMG keeps stats on this issue, and if they are willing to answer questions. I tried to find contact details online, but nada ... does anyone have an email address?

Thanks!

Barry O

You could check on the AMG Private lounge, but I doubt that information is floating around. The best bet for information is on the C class forum. There are a ton of differerent threads on the 156 engine issues/ concerns.

betrezra

You might be able to pull a valve cover to see if the head bolts were replaced. From what i read here the bolt tops are different if replaced. Maybe they can run a borescope to see this?

GatorMB

There was a AMG resource engineer searching for failed head bolts in this forum a couple of years ago.
Some 6.3 engine owners have replaced them with ARP stud kits.
I believe it can be done on a strong healthy engine one at a time in sequence without disturbing the head gasket. (theory)
Studs have superior clamping abilities as opposed to cap screw bolts. Most all race engines are prepped with studs.

I would collect all warranty information before modifying though.

2 cents, Gator

CDM Motorsports

i know people who have done that successfully changing stud 1 by 1.

The head bolts were an issue but it isnt as common as some people make it out to be.

Jim's500E

At this point in time and the car's ages.....if it ain't broken yet don't worry about it. Just my 2 cents. Only a very small numbers of engines thru certain numbers (AMG lounge has/had the affected engine numbers) actually had bolt failures. If you got the cash and want to be pro-active the APR head studs are the way to go. I know of a few local MB mechanics who off-duty have the done the head bolts (new factory upgraded ones) for 2500$....I was concerned too when I bought my 63, but 4 years later I can say that the concern was not warranted.

And from the few other M156 owners I know who HAD the bolt problems it was because they tracked/beat on their cars...which is really what AMG intends, yes?