Opinions needed on Headbolt replacement
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From: eNyCe
Steel Grey Metallic C63!!
Opinions needed on Headbolt replacement
If you had the option to have your headbolts replaced on your C63, would you have it replaced even if your car has no issues? I would like to hear the pros and cons of having it replaced. I understand that there are risks with opening a can of worms by touching a motor with no issues.
Your input would be greatly appreciated.
Your input would be greatly appreciated.
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From: eNyCe
Steel Grey Metallic C63!!
I have the option to replace them free of charge. I don't really have any issues with mine, other than oil consumption. I was offered the option to have them replaced, but I'm just worried about opening a trouble free motor, in an attempt to resolve a potential issue.
Would you do it?
Would you do it?
Last edited by I am Jeff; Dec 12, 2013 at 12:40 PM.
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From: eNyCe
Steel Grey Metallic C63!!
Thanks for the response! I do intend to keep the car, but was just worried about any potential issues that may arise. My friend intends to replace a bunch of parts once he opens it up (gaskets, headbolts, etc...)
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I would do it too knowing it is free of charge and that it will give you piece of mind.
Now you are saying your friend will be doing it.... how experienced is he?
I would rather be picky about the tech who will work on my engine for this job.
Now you are saying your friend will be doing it.... how experienced is he?
I would rather be picky about the tech who will work on my engine for this job.
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From: eNyCe
Steel Grey Metallic C63!!
He's a tech that works on these motors on a daily basis.
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I have the option to replace them free of charge. I don't really have any issues with mine, other than oil consumption. I was offered the option to have them replaced, but I'm just worried about opening a trouble free motor, in an attempt to resolve a potential issue.
Would you do it?
Would you do it?
Hella yea. Read the sticky in this forum. Replace everything with the updated parts including the lifters. Everything is one time use torque to yield any way. Hydrolock equals a blown motor.
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The headbolts can fail anytime. Dealer has told me even low mile cars (less than 10k have failed). Additionally anyone that does any research on the 6.3 motor cars is going to come across this potential failure and either not buy or low ball you. MBZ will not replace them until they fail, so get a long warranty.
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Merc,
Not to be a stickler, but the head bolts are torque to yield and many of them are under the cams. Hence replacing one at a time is not a viable solution. If you replace one you have to replace them all including pulling the heads as the head gaskets are compromised when all the head bolts are taken out. I wish there was a short cut, but there isn't.
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C63 AMG
Merc,
Not to be a stickler, but the head bolts are torque to yield and many of them are under the cams. Hence replacing one at a time is not a viable solution. If you replace one you have to replace them all including pulling the heads as the head gaskets are compromised when all the head bolts are taken out. I wish there was a short cut, but there isn't.
Not to be a stickler, but the head bolts are torque to yield and many of them are under the cams. Hence replacing one at a time is not a viable solution. If you replace one you have to replace them all including pulling the heads as the head gaskets are compromised when all the head bolts are taken out. I wish there was a short cut, but there isn't.
Sorry but this is totally incorrect.
Search for my stage 3 and head bolt replacement thread where I switched each bolt to a stud one by one without removing the head.
The head gasket will not at all be compromised. There is no force on the head with the engine not running. All other 9 bolts that remain in while one is removed is well over 150,000psi clamping force.
Simply remove cams and replace one at a time.
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From: eNyCe
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Thanks Duane. I was thinking the same thing, if done properly, the risks are far outweighed by the rewards. What are the parts that should be replaced? Bolts, gaskets, lifters. Anything else?
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if it was being done for free by a dealer and by a tech who had done it before and had access to MB techinical supprt services, yes
by some guy is a garage, no
from what I can see it can be done one bolt at a time but the cams must be removed
a fairly complicated procedure
if you go that far might as well remove the head and replace the gaskets and torque the bolts per spec
by some guy is a garage, no
from what I can see it can be done one bolt at a time but the cams must be removed
a fairly complicated procedure
if you go that far might as well remove the head and replace the gaskets and torque the bolts per spec
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Sorry but this is totally incorrect.
Search for my stage 3 and head bolt replacement thread where I switched each bolt to a stud one by one without removing the head.
The head gasket will not at all be compromised. There is no force on the head with the engine not running. All other 9 bolts that remain in while one is removed is well over 150,000psi clamping force.
Simply remove cams and replace one at a time.
Search for my stage 3 and head bolt replacement thread where I switched each bolt to a stud one by one without removing the head.
The head gasket will not at all be compromised. There is no force on the head with the engine not running. All other 9 bolts that remain in while one is removed is well over 150,000psi clamping force.
Simply remove cams and replace one at a time.
then you say there is 150,000 lb (force), btw NOT psi which is a unit force/area
(probably closer to 140kip, but who's counting, lol)
to get psi = 150,000 lb / area in^2 of the head
head area ~ 250 in^2 ~ 600 psi
releasing 1 bolt may distort the head and gasket or stretch the other bolts (even the ones just installed)
better to release and apply in sequence and in stages
will it lead to early failure? who knows, probably not
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C63AMG, NIssan NX2000, Pontiac Fiero GT
According to gasket mfgrs many hi po head gaskets are made with spring steel . When running, the head , gasket and headbolts look like a trampoline. Then there's the surface "bite" of the gasket on head/block. The diesel hot rodder blogs I read mostly frown on one at a time.
I want to believe, I want to believe. But seems like the head off, lifters, TTY head bolts are the way. But if the cams could stay in I would try it.
Sure wish we could get some more input on headbolt logos...You know, the dream that only one vendor produced a few headbolts and only they are bad. Finally, none of our engines contain those headbolts.
I want to believe, I want to believe. But seems like the head off, lifters, TTY head bolts are the way. But if the cams could stay in I would try it.
Sure wish we could get some more input on headbolt logos...You know, the dream that only one vendor produced a few headbolts and only they are bad. Finally, none of our engines contain those headbolts.
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first you say there is NO force on the head
then you say there is 150,000 lb (force), btw NOT psi which is a unit force/area
(probably closer to 140kip, but who's counting, lol)
to get psi = 150,000 lb / area in^2 of the head
head area ~ 250 in^2 ~ 600 psi
releasing 1 bolt may distort the head and gasket or stretch the other bolts (even the ones just installed)
better to release and apply in sequence and in stages
will it lead to early failure? who knows, probably not
then you say there is 150,000 lb (force), btw NOT psi which is a unit force/area
(probably closer to 140kip, but who's counting, lol)
to get psi = 150,000 lb / area in^2 of the head
head area ~ 250 in^2 ~ 600 psi
releasing 1 bolt may distort the head and gasket or stretch the other bolts (even the ones just installed)
better to release and apply in sequence and in stages
will it lead to early failure? who knows, probably not
Clearly talking about force from a running engine.
Sure replacing the gasket and removing the head is ideal in a perfect world. Is it necessary, doubt it.
Running stage 3 power through mine for 10,000 hard km. you want to tear your heads off and remove the engine to replace, go hard.
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Look up clamping force of a bolt.
Clearly talking about force from a running engine.
Sure replacing the gasket and removing the head is ideal in a perfect world. Is it necessary, doubt it.
Running stage 3 power through mine for 10,000 hard km. you want to tear your heads off and remove the engine to replace, go hard.
Clearly talking about force from a running engine.
Sure replacing the gasket and removing the head is ideal in a perfect world. Is it necessary, doubt it.
Running stage 3 power through mine for 10,000 hard km. you want to tear your heads off and remove the engine to replace, go hard.
it is static and does not matter whether the engine is running or not
it is what prevents combustion from blowing the head off
the average (not peak or impulse) force it resists IS generated when the engine is running and is:
~ comp ratio x atm pressure x vol eff x piston area
~ 11.3 x 14.7 x 1.03 (estimate at peak) x 12.6 ~ 2200 lb
dimensional analysis = unitless x lb / sq in x unitless x sq in = lb (force)
side note bearing throw is ~ 2.4 in or 0.2 ft
torque = F x r = 2200 lb x 0.2 ft ~ 440 lb ft of torque
the actual clamping force is ~140,000 lb or 14,000 per bolt
assume 2.5 bolt per cylinder (10 bolt/ 4 cylinder) so each cylinder has ~ 35,000 lb of restraining force for 2200 lb of applied force
if you 1/2 *** something you get 1/2 assed results
as I said, probably makes no difference with the safety factors involved
if I were to do it:
release tension in ALL bolts per the mfgs removal sequence (1-2 turns should do it)
then replace 1 bolt at a time in the mfgs recommended install sequence
apply an extra 30 to 45 deg of final torque angle to compensate for the previously compressed head gasket
but I would probably pay someone to do it right if I were actually doing it...but that's just me
