When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I just hit 86K in my 07 E63. And no, it's not one of those issues....sorry. I was at Benz Elite Automotive in Fairfax VA yesterday, having my both a new custom steering wheel installed and stability control steering angle sensor.
I sat down with the owners and we had several discussions, one question I had was how many M156 have you actually seen, that had head bolt issues. And the number was surprisingly small, but they advised me to have my head bolts addressed before they become a issue.
Emile said typically they see the issue arise around the 90k mark. And I'm a few thousand from that mark as we speak. So we priced out the new revised head bolts, valve tappets, valve cover gaskets, and cam adjuster gaskets.
Surprisingly all the parts come in at around $1600 and a $1000-1100 for labor for a grand total of $2700. So I'm planning on having this done, so that I never have to worry about it ever.
As I've said numerous times, I've never had any head bolt issues with any of my (3) AMG's I've owned. But as some have said, it's not if but when. Some of indicators are low engine coolant, or white smoke from the exhaust.
Keep in mind that the $2700 is just for replacing the bolts, the price goes up if any of the bolts are broken. Thereby warranting removing of the heads, to remove the broken bolts. I certainly hope I don't have anything broken.
So I think that is cheap insurance, if you plan on keeping your E63 for awhile, like me.
I would do the same if I had ended up with a M156 car. Piece of mind. I am surprised that a professional shop would be willing to do it with the heads on, not that it won't work perfectly. The updated bolts themselves are very affordable.
When it happened to me, I wished with every cell in my body I could've paid the $3K preventative instead of the $7500 after the fact. I opted to put in new lifters and had to replace a pair of camshaft adjusters as well.
This is the preferred method if there aren’t any broken bolts. You have to removed the cams, then replace one bolt at a time, thereby keeping the clamping force on the heads. That way you don’t need to replace the head gaskets. Unless you have a broken bolt, then you have no other option but to remove it at that point. To me it’s peace of mind and a relatively cheaper fix, all things considered. And you never have to worry about it again. And since your already in there why not replace the valve tappers, with the upgraded ones found in the SLS, the M157 engine. I’m looking at having it done either this month or in September. But what ever I decide I want the do it ASAP. Because once you start losing coolant , or you have white smoke from your exhaust, the heads must come off regardless. And that is more like $5000-6400 as the engine must come out.
When it happened to me, I wished with every cell in my body I could've paid the $3K preventative instead of the $7500 after the fact. I opted to put in new lifters and had to replace a pair of camshaft adjusters as well.
Either pay now for preventative maintenance or pay later for repairs. I’m heeding your words. 👍🏽 And I’m choosing to listen to someone that has been there. Thank you so much.
1999 C43, 2008 P30 E63, 2014 SQ5, 2024 Model Y Performance
Originally Posted by Yuille36
This is the preferred method if there aren’t any broken bolts. You have to removed the cams, then replace one bolt at a time, thereby keeping the clamping force on the heads. That way you don’t need to replace the head gaskets. Unless you have a broken bolt, then you have no other option but to remove it at that point. To me it’s peace of mind and a relatively cheaper fix, all things considered. And you never have to worry about it again. And since your already in there why not replace the valve tappers, with the upgraded ones found in the SLS, the M157 engine. I’m looking at having it done either this month or in September. But what ever I decide I want the do it ASAP. Because once you start losing coolant , or you have white smoke from your exhaust, the heads must come off regardless. And that is more like $5000-6400 as the engine must come out.
DO IT!!! $2,700 is the lowest I have heard anyone get quoted. I just replaced 3 cams, valve tappets, head bolts, and injectors. The injectors failed, the rest was preventative. For what it is worth, the only tappets they install now are from the SLS. When I was having them swapped out the dealer showed me the new part # cross referenced to the SLS part #. Mind you these aren't the SLS black series tappets, those have a special coating that reduce friction.
DO IT!!! $2,700 is the lowest I have heard anyone get quoted. I just replaced 3 cams, valve tappets, head bolts, and injectors. The injectors failed, the rest was preventative. For what it is worth, the only tappets they install now are from the SLS. When I was having them swapped out the dealer showed me the new part # cross referenced to the SLS part #. Mind you these aren't the SLS black series tappets, those have a special coating that reduce friction.
Also, the SLS engine code is M159
Good catch, the M157 is the 5.5 TT, and the M159 is the modified M156 made specifically for the SLS with a dry sump. Yes, $2700 is a great price, and I'm going to take advantage of it too.
I've been going to Benz Elite Automotive since 2009, and have a good repour with them. And they discount me when ever possible. I'm looking at scheduling it for Sept 10th, that would give them 4 days to work on it.
I know that the valve tappets are like $25 a piece and I would need 32 of them. And the head bolts run around $300. Then you have all the gaskets (valve cover, cam adjusters, coil packs gasket) and miscellaneous along with a oil change and filter.
I'm looking forward to getting this done, definitely for peace of mind. One less thing to worry about. So if you live in the Northern Virginia area, and looking for a shop with trained Mercedes Benz Technicians, look no further than Benz Elite Automotive in Fairfax, VA. That plug alone just saved me a few bucks off my bill.
The irony to me is that I called Benz Elite several months ago for this same job... the lady who picked up the phone said it costs $4000+ and the shop did NOT recommend it unless I was having any problems. Since it affects <0.1% of M156 engines, I will take my chances! But $2700 is certainly a fair deal.
I should add that anyone looking to do this job, especially after a head bolt has snapped, should do their in-depth research on what the work entails. A couple shops that I'd consulted frantically took me for a ride on expensive diagnostics to "be sure" despite having multiple positive diagnostics from various places including the dealer.
The irony to me is that I called Benz Elite several months ago for this same job... the lady who picked up the phone said it costs $4000+ and the shop did NOT recommend it unless I was having any problems. Since it affects <0.1% of M156 engines, I will take my chances! But $2700 is certainly a fair deal.
Cyrus
Cyrus,
Gretta was correct in the fact that this only effected <0.1% of all M156. We all know that the issue typically raised it's ugly head in high mileage engines. Emile told me, that they recommend doing this procedure, if your car still has the original head bolts and before the car reached 90K.
Now if you have low coolant or white smoke from the exhaust, then the heads have to come off, and it will be much more expensive. And that runs $4000+ Now he did say that if the leak is sever, where the oil looks like a milk shake, that will warrant pulling the entire engine out, that's about $6500.
But I'm getting this done, before I have any indications of an issue. It's better to do pre-emptive maintenance, then paying for repairs.
I'm hoping to get mine done one of these days. Mine just turned 87k miles yesterday and I have all the parts to do it (minus the updated lifters) to do the job. I just need to wait until my mechanic has a free weekend to bust it out.
Would be nice if we got real clarity on the true occurrence rate of failures. It really does seem to be hit or miss, and considering that MB covers the fuel issues on the W211s I'm sure if the numbers warranted it the NHTSA would have issued a recall or let MB handle it the same way as the fuel issue. I understand the nature of the type of engine we have but it seems a lot to throw at cars not showing any issues.
That said, these cars are a blast to drive, and seeing the manner in which the bolts actually fail, if you're someone who gets on it often I can see taking the precaution. Similar upgrades are the norm on some other blocks for holding anything beyond stock power, so I see the case for it if you're modding. Not a fan of such a large gray area, but it literally seems there's not a single high performance car that doesn't have some kind of quirk like this.
I do think MB should be a lot more accommodating with their pricing for preventative maintenance in cases like this, however, considering that it's accepted by everyone that the original bolt design is substandard. The way some of these things are handled are the only thing that give me pause with MB as a whole, because the overall driving experience lives up to "The best or nothing", but leaving worries like this in the back of everyone's mind certainly does not.
The fuel issue was judged as a safety concern and affects many many vehicles. I am certain they are just covering themselves legally. Unfortunately the government doesn't care if you hydrolock your engine. I am sure the occurrence is well under 3% but piece of mind is worth it if you don't win the metallurgical lottery.
I had a conversation with Emile and Eddie last Friday, their both Co-Owners of Benz Elite Automotive, Mercedes Benz Trained Technician, and ASE Certified Mechanic. They explained it this way, AMG used inferior head bolts in the M156, we all know this and some have failed, but not all.
Some owner haven't had any issues, and the failure rate is <0.1% of the total M156 engines produced during it's run. He said that when the car has roughly 90K on the odometer, that is typically when you start detecting small issues related to head bolt failure.
Low coolant in the reservoir, puffs of white smoke from the exhaust. More severe indicators are a lot of white smoke from the exhaust, oil that looks like a milk shake, or CEL. But these are all symptoms of a blown head gaskets, and your right.
Until you attempt to remove the heads, and the bolts break off. Only then will you have your culprit, broken heads bolt not applying enough clamping force to keep coolant out of the combustion chamber.
Eddie showed me video from a bore scope, that clearly shows coolant leaking into the combustion chamber. He explained to me, that this is one of the tools that they use to diagnose with, as an indicator of possible broken head bolts or blown head gaskets.
For me this is a no brainer, replace the inferior head bolts before they become an issue. Then and only then, will you have peace of mind.
If we say there there was 30K M156 cars produced, .1% translates to just 30 cars that have experienced head bolt problems. The failure rate is definitely much higher than that.
If we say there there was 30K M156 cars produced, .1% translates to just 30 cars that have experienced head bolt problems. The failure rate is definitely much higher than that.
I will agree with you, but the failure isn't as high as people make it out to be.....agreed? When I talked to Emile he said that he has only replaced 3 sets of head bolts on the M156 engine.
In the W204 C63 threads, they have a mileage poll going to show how many miles they currently have, and if anyone replaced their head bolts. It's very interesting.
That thread makes it seem for active members it's somewhere between 5-10%, with the approach towards 100,000 miles being where things really start getting squirrely. I think at 85,000 I'd probably get it out of the way for peace of mind. I do have a warranty on mine that should cover any repair costs should it happen before then, assuming it's obvious enough to be caught before major damage is done. I still have to say that I don't like the vibe of the situation. Having such a major failure floating around in your mind as a real possibility doesn't really enhance the driving experience, hah, at least not knowing that there could be a fine line between covered by a $5-7k warranty and a catastrophic failure requiring a full rebuild or new short block.
Overall though it just reinforces to me that these aren't cars most people should get without a warranty to keep you covered or a willingness to accept them needing to be totaled out for a major failure once the miles get up there. Nothing really touches the driving experience, though, so I think I'm stuck here for a while =p Guess it's just part and parcel for what is basically a street car with a racing block and all the fickleness that can entail, though this potential failure is due to subpar bolts and not the stress of hard driving on the engine per se. As I rambled about before, I'd feel better on the whole if MB were more up front about issues and more accommodating about rectifying them rather than enthusiasts and curious customers having to resort to compiling information on our own, initiating complaints to the NHTSA, and filing suits to try and get clarity or compensation.
I do get that MB aren't the first and won't be the last to play shell games and the like to avoid revealing the full scope of issues, though. It's just very telling that the consensus is pretty much don't deal with the dealer or MBUSA unless you have to because it will be a headache and stay away from them for repairs unless it's a vetted warranty failure.
No doubt. I'd expect that they'd cover failure out to a reasonable mileage beyond the standard warranty or offer a reduced repair cost. Considering that this is only a fraction of engines affected and under specific circumstances that good will would go a long way.
Go to YouTube and search for tasos moschatos M156
But I wouldn’t advise doing this yourself, my advise is to take to someone that knows what their doing.
I did my own, and would be willing to help others but I am in NM. It takes me about 1 day on a weekend to remove the radiator, and start the work to end the next morning when I am fresh. I don't rip through it, and I even do the adaptation with xentry afterwards. If I had help with removing all the parts, labeling, etc I could do it in 6 hours. The parts are around $100 if I remember correctly, you will need the cam timing bolts from ARP, headbolts, coolant and the diamond coated washers. Doing pullies, and plugs adds some time to the job but I think $1000 in labor is fair, not what they are charging.
Go to YouTube and search for tasos moschatos M156
But I wouldn’t advise doing this yourself, my advise is to take to someone that knows what their doing.
I wouldn't have done this without Tasos's help. I used the wrong timing mark (My 40' was heavily painted over). Zero timing kicks codes but doesn't hurt anything in the engine. Technically I have done the timing deal twice I had to get the new washers, and while I was at it I bought a second timing tool kit so I could hold the left while I set the right side.
I wouldn't have done this without Tasos's help. I used the wrong timing mark (My 40' was heavily painted over). Zero timing kicks codes but doesn't hurt anything in the engine. Technically I have done the timing deal twice I had to get the new washers, and while I was at it I bought a second timing tool kit so I could hold the left while I set the right side.
And you Sir.........are definitely one of those that know what they're doing.
Working on consolidating all of the info for M156 top end service on our blog related to headbolts/lifters etc to make it easy for anyone who wishes to attack this themselves or just needs some clarity on what is involved.
08-03-2019, 06:32 PM
