fidget

Good Morning everyone
I know this has beaten to death. I'm purchasing a single owner 2009 C63 with under 20K mileage so its been a weekend only garage kept 14 year old toy. Has a crazy long service history of all the oil changes and standard maintenances and recall work done. The Mercedes dealer is offering the throw in and do the head bolt replacement as part of the purchase. Which is great. But they are doing the single bolt removal method and only replacing the valve cover gaskets, valve cover bolts, and the head bolts. Is there risks in compromising the head gaskets when removing a single head bolt at a time with a car this age and mileage? I'm getting conflicting statements when calling around to 4 local Mercedes shops in my state. I had 2 shops tell me that once 1 bolt is removed the seal of the gasket and vacuum in the engine will fail and its not a matter of if but when the gasket will begin to leak. And 2 other shops telling me 1 at a time should be fine as long as the shop drains the coolant and takes the bolts out in the proper order listed in the Mercedes manual. I know some on here will say leave well enough alone but if the dealer is willing to upgrade the bolts I'm down. But am more concerned about if they are doing it incorrectly and causing basically the same issue down the road with a failed head gasket. When the M1156 head bolts were done under warranty or recall was it one and done? Or both heads removed and gaskets also replaced? What's everyone's thoughts?

BLKROKT

Since it’s a MB dealer I’d ask them to do it the “correct” way, by the book, and remove the heads, replacing the bolts and gaskets.

But plenty of people here did the one bolt at a time method and I can’t remember seeing any failures yet. It’ll be fine if that’s how they have to do it.

skullbox15

Do they offer some type of warranty period on that work?

deadlyvt

It's fine to do one bolt at a time... and it doesn't matter the order as it's only one bolt out at any time.

roadtalontsi

Worst case it fails, you blow a head gasket, maybe bend a rod. Seems cool to do one at a time I guess. lol
The fact that a dealer even allows that is insane. I hope the service records aren't with them. I bet they've never drained the oil cooler during an oil change too. I wouldn't want the dealer touching my car or the 2 independents that said it's fine.
Any one with a brain wouldn't risk possible failure consequences vs doing it properly.

Jasonoff

You think replacing one bolt at a time will compromise the head gasket?

roadtalontsi

absolutely. Why would you do 85% of the work correctly? That'd be like having a valve seat issue on cylinder one, so you pull the head off only to have cylinder 1 valves addressed. Forget the other 3 in the cylinder head they are working just fine. It's just the same old lazy half assed work. Then people wonder why their car has problems.

Jasonoff

Just to be clear, removing 1 head bolt on a head with an uncompromised gasket will absolutely compromise the gasket because the 9 other bolts won't have enough clamping force? Replacing bolts one at a time as a preventative measure is only doing only 85% of the work?

fidget

Thanks for the input everyone. Great feed back so far. But just like making calls around to the shops it still seems 50/50. Would love to hear from those that have done the 1 by 1 bolt replacement and had head gasket failure or engine issues later. The forum is full of users that did the work or were going to do the work. But goes silent after the work is done. Assuming that's a good sign since they do not come back with tails of doom. My options are let them do the 1 bolt at a time (Included). Let them charge me for head gasket replacement ($4000ish for engine removal)....., or walk away. Currently they are fine with replacing the heads bolts at their cost and also installing the 63 Motorsports cam adjuster plates while they are in there if I purchase the plated online and ship there. Work is warrantied for 90 days.

lo-fi

You're going to have to make this decision yourself. Let's say one or two people did the one by one and had an issue later, but another eight did one by one and have no issues to report. That tells you absolutely nothing. Perhaps the one or two that failed were high mileage cars with looming issues regardless. Perhaps they were running amateur hour tunes. Perhaps they didn't apply proper torque. You see where I'm going. It seems you're looking for 100% assurance that one by one will never result in a future problem. Most don't think there is any issue doing one by one, some do think there is an issue. That's probably as good as gets.

fidget

Appreciate the response and time. I was more or less getting feedback and comparing notes from a large community or MB owners. Thought it would be better than calling around getting quotes. Would rather be here hearing from the community that has actually done the work vs some MB shop technicians I have talked to that have never seen a W204 C63 up on lift getting engine work done. So far I'm up to 9 shops I have called with the same question. Each shop was different with their opinion. Of those only 2 had "actually" done the work. 1 under full warranty and removed the engine and replaced the head gasket along with the bolts and anything else required for the recall. Another that did just the 1 blot at a time method on a couple different E and C class M156 engines and provided a 1 year warranty on the work. So in the end your right. Its ultimately up to me and if I'm going to enjoy the car or constantly worry if I'm bought a car that will grenade on the road. The end goal was to see if they were doing the work properly? Which sounds like not the MB recall standards. And....if 1 by 1 was considered good enough and better than sticking to the OG head bolts or 1 by 1 just causing more issues. I had hoped for some members that have done it to mention success stories and being fine 10s of thousands if miles later. And any members with issues to come to the podium and mention they grenaded the engine because they failed to replace the head gaskets and experienced leaks.

deadlyvt

I've done the one bolt at a time method on other cars and know of 2 people who have done it on the m156 none have had any head gasket failure. The pressure from the other bolts won't allow the head or gasket to lift (you could probably removed 2-4 bolts at a time and have no effect to the gasket)
If the gasket is already compromised it won't be reseated after.

BLKROKT

Why don’t you just wait and get a non headbolt affected car? This doesn’t sound like the car for you.

roadtalontsi

doing all the work to do the headbolts and then being to lazy to actually remove the cylinder heads 85% of the work. Steps avoided... draining coolant, removing timing chain tensioner, timing chain idler gears on the cylinder head and unbolting exhaust. Maybe it's more like 93% of the work.

And yes removing 1 bolt at a time will very likely compromise the head gasket. How many head bolt failures have you actually seen? Did you see multiple broken bolts or one?

roadtalontsi

I think this says it all.

Motor removal is not necessary unless the vehicle has long tube headers. It also is only about 12hrs labor + alignment at most. I would never have anyone work on my car that can only stand behind their work for 90 days. What a scam.

Vladds

I thought about the procedure the same way. I also heard a dealer offering to do 1 bolt at the time, which shocked me.
I am not sure that it's 85, or 93% of the procedure.
But if a dealer does it, then why not.

Jasonoff

I am talking about an uncompromised head gasket. No broken bolts. Just swapping old design bolt with new design one at a time.

Dumping the coolant is part of the procedure. Why lift the heads if you don't have to. It's quite a bit more work that's completely unnecessary on an uncompromised head so I wouldn't call it lazy. Obviously verify before hand that the HG isn't compromised and if it is you have no choice but to pull the head.

Do you have any data to support "And yes removing 1 bolt at a time will very likely compromise the head gasket." or it is just an assumption? There's probably at least 10 members on here who have done it this way, who knows how many more outside of this forum. I'm going on 7 years since a friend and I have done both of ours. Maybe we got lucky?

austingtir

The question you have to ask yourself is are you feeling lucky. Say you decide to do the 1 by 1 bolt method and break a head off one. Then your probably pulling the engine out for sure.

Really the failure rate is actually quite low. If you look at all the videos and thread on various forums on this issue most of the bolts iv seen pulled out are usually not that bad. (I know its the design of the bolt too). Most imo arent corroded enough yet to fail. The mere fact that most people are getting these bolts out without them failing when undoing them really says it all. All you are doing is a case of preventative maintenance and hope you dont fk the headgasket up in the process.

But some rare cases are so corroded they are physically corroded into the head again no way your getting those out without stripping the engine down.... usually these ones are the ones that fail completely and milkshake the engine.

G_Money

They are going to replace the headbolts and cam adjusters with no additional charge? I'd go for it... You have to realize that even on pre-2012 cars the head bolt issue is incredibly rare... Think about how many of these engines they made... They made like 40,000 C63s alone, and I have no idea on the other models (which would have all been pre-2012 cars, btw)... Now compare that number with the number of failures you've seen posted about... It's miniscule. And even if it does happen, you can still get it fixed without destroying the engine as long as you're paying attention.

But tbh it doesn't seem like this is the car for you if you're going to be losing sleep on it like this... The dealership is giving you a pretty good deal, and assuming its a Mercedes dealership, I'd be inclined to trust them... If the car was really a POS or they thought anything major was wrong with it, they'd send it straight to auction. This is a place that, ostensibly, is regularly selling quarter million dollar cars, they aren't going to risk the hassle to make like $5k on scamming some kid in to buying a lemon. Just think about it that way.

fidget

Thanks for all the input and opinions everyone. Engine is back together and pickup new purchase next week. They allotted me 16hrs of labor before "charging" so the tech said screw it and removed the heads without needing to remove the engine, replaced head gaskets, head bolts done, took off the intake manifold to inspect for giggles, replaced the crank case vent valve hose because old and fell apart, replaced the came adjuster plates, and put back together with under 3 hours to spare. Lifters and lobes looked great so returning the "just in case" lifters I had purchased. Have to wait until next week to pick up. Shop has a new scanner on order for delivery on Monday. Engine fires up fine but they want to check that timings and metrics look good as well as doing a crankshaft relearn if necessary. Was willing to let them do 1 by 1 but they ended up doing the extra work in the end. Again thanks everyone for thought and opinions. Most of the FCPEuros list of gotchas on the M156 have been taken care of.

Bahnstormer

Just curious, did you get a chance to see the old head bolts once they were out, any corrosion?

fidget

All the old bolts are in the box that the new ones came in and are in the trunk of the car. I will take pics and upload to this thread as soon as I pick up the car next week. I was curious what they looked like and asked them to hang on to them.

fidget

And as promised here is the pics of the condition of the bolts that were replaced. Not to horrible but glad its done.