Pierre-CT

I have a strong interest buying in a CLK63 AMG with a MY07 or MY08 M156 engine. The headbolt and valve lifter issues make me nervous.

There seems to be a broad consensus that one should preemptively replace the headbolts before problems occur – is this correct, or are there advocates for leaving it alone until the problem presents itself (“Add Coolant”). I would never attempt the job myself, it would be done via a mechanic (I understand cost is around $6k).

Have MB or AMG issued any guidelines or advice on how to address this issue?

What is the part number for the correct headbolts?

Same for the valve lifters – should these be replaced preemptively (perhaps at the same time as the headbolts)? I’ve been told cost is around $2k?

What does MB / AMG say?

What is the part number for the correct valve lifters?

Is the engine otherwise sound? In other words, after I invest the money to correct these issues, will I enjoy years of high-performance, hassle-free pleasure from the engine? Or are there other issues I need to be concerned about?

Many thanks!

BLKROKT

Replacing the head bolts one-by-one - as long as the head gaskets have not already been compromised - is a significantly cheaper way to do it. Search here, it's been done by a few members recently.

Merc63

If you got the $$ spend it

AMG3.2

I'm in the same boat here so I'm going to chime in.

I did a bit of calling around this past week regarding the "one at a time" method and was advised by almost all that I spoke to to leave it be if/until I do receive coolant low messages.

Reason being this: The techs would advise that while this method is usually successful, they cannot guarantee the head gasket won't leak after the job is done. At that point, it'd be a full heads off job after the cost of the headbolt swap.

It almost made me think that the preventative maintenance could end up opening up a can of worms, even though the chance is small.

Not saying I'm not going to do it, but definitely gave me something to think about.

ZephyrAMG

If you:

1. Change gaskets at the same time
2. Have it done with the complete proper torque specs
3. Have it done in the correct, distributing force order
4. Change all associated bolts with new bolts (for one time torque)

You will not have any issues. It;s honestly not a big deal. Have some one who knows the engine work on it. My guy knows the engine inside and out and has already done several with absolutely no problems after....

Talk to Richard at Autohaus Frankfort in Murrieta...just call him and let him tell you how much of a perfectionist he is. Let him tell you about the procedure. Worth every penny. His shop is like a brain surgeons OR...clean and precise.

Merc63

Changing a bolt one at a time is completely fine if done correctly. Anyone that tells you otherwise blah. Just because they are a mechanic doesn't mean they are smart.

Diesel guys do this all the time, BMW has a shop procedure for doing it. Etc etc. If you want them changed have it done one by one with the MB sequence, drop the oil and coolant. Bingo bango done.

If you leave it be, it's a 100% heads off job if that coolant leaks, a member already did that real world test and he couldn't get the seal back.

Just be damn sure you hire someone that knows these engines and ideally had done it before.

glennhl

I agree 100% with Merc63. The mechanics are just covering their butts. They haven't done the 1 bolt at a time and they just want to be able to say I told you so if something happens afterwards. Personally I'd rather do 1 bolt at a time then to put on new gaskets. There is a better chance of screwing something up when you replace the gasket. With one bolt at a time, it's pretty darn hard to screw something up.

Pierre-CT

Thanks for all the input, this is a very daunting issue for non-mechanics!

It sounds as though the best bet is to find a mechanic who actually has experience of changing headbolts on this engine, which is easier said than done for those of us away from major metropolitan areas. Are there technical terms for the “one at a time” versus “all at once” methods for doing the procedure?

Are there questions one can ask that will reveal whether the mechanic does actually have experience with the M156 engine, or is just looking to land a high cost job?

Nobody has mentioned anything about the valve lifters – I know the class action law suit went nowhere, but I have read several posts from guys whose engines suffered some pretty severe damage as a result of this issue. Is it another fundamental problem with the M156, or is it just a question of using the wrong oil? Does anyone replace these preemptively? Are there different techniques?

Thanks!

Merc63

Replace the lifters with sls. My lifters are getting noisy, I changed oil, helped some.

If they have the Mercedes tools to remove the cams that would be a good start.

AMG3.2

Merc, couldn't he/she also replace with updated M156 lifters instead? A bit cheaper than the M159 lifters.

P/N 156-050-02-25

Phil Chow

How much are the M159 Lifters vs the updated M156 lifters?

I'll probably end up doing the Lifters/Bolts if I end up driving my car more often...

mcgrath

The updated 156 lifters are the SLS lifters. They are coated on the tops grey in color. The only other lifters are the SLS BS which are DLC coated all around (black). I had a bad exhaust cam adjuster which turned into worn lifters and cams. I replaced all the cams, adjusters. Put the SLS BS lifters in and while I was there I did the headbolts one at a time. I had zero coolant loss before and after 3,000 miles I still have zero coolant loss knock on wood.

AMG6.3

If it ain't broken why change them. If you notice low coolant you have a problem.

Jasonoff

Do you have pics of yours when you did the studs?

DP63AMG

I replaced my headbolts and lifters about a month ago. It cost me $2700 and so far so good. No low coolant warning and it seems to be running stronger than before.

AMG3.2

Really? I just assumed they were different parts since the part numbers are different.

Here's his DIY thread where you can see them.

https://mbworld.org/forums/c63-amg-w...swap-m156.html

Jasonoff

I don't think that was his motor.

Merc63

Pics are in the thread when I built the car to stage 3.

akmatic63

It all depends how you look at it- everyone will have a different opinion: Do it just in case vs wait till something happens.

If I was in your position, I would incorporate the cost in your total purchase price, considering the age and also depending on the mileage of the car. If you do some digging maybe you can find one that already has the updated bolts from the dealership or if the previous owners has records.

Then you also have options on how to attack the situation: go with OEM updated parts or go with aftermarket upgraded parts such as weistec, especially if you plan on doing future modifications.

Jasonoff

It's much cheaper to do it before HG failure.

But, gambling is fun...

Pierre-CT

Today I went to the mechanic who does a great job on my '95 E320 cab, and he quoted me $3k for headbolt and valve lifter replacement, via the "traditional" method (i.e. not one bolt at a time). He has experience with this and feels comfortable doing it this way. Fine by me - I know I will feel much more comfortable taking care of the issue before I get presented with an "Add Coolant" light when I'm on a family road trip 200 miles from home.

I guess the point is that it's worth shopping it around - because the bulk of the cost comes from labor vs parts, there's a wide range of prices for doing the job.

A question I was about to ask - would the replacement be made superfluous by future upgrades to the engine? I.e should one consider spending $5k (as an example) to upgrade certain engine parts (e.g. pull out more BHP or other improvements) AND fix the factory problem versus dropping $3k just to fix the factory problem? If so, what upgrades would fix the problem and improve the engine?

BiturboSF

Whats the name of the shop you took it to? & did they have previous experience swapping the head bolts? Looks like you're local to me

DP63AMG

The name of the shop is:
Precision Motorworks

http://www.precision-motorworks.com/...ce-tuning.aspx

The owner is Chris. Great guy.