+- STD (https://www.superturbodiesel.com/std)
+-- Forum: Tuning (https://www.superturbodiesel.com/std/forumdisplay.php?fid=6)
+--- Forum: Engine (https://www.superturbodiesel.com/std/forumdisplay.php?fid=7)
+--- Thread: 102mm vs 115mm head bolts (/showthread.php?tid=7678)
102mm vs 115mm head bolts - BoostedW124 - 03-28-2017
I just got my head in a good machine shop so now it's time to hit pelicanarts and order everything to tie this up. What is the difference between the short and long size head bolts? I would assume that 102mm is for regular set up and the longer 115mm is to accomodate the thicker head gasket AKA repair head gasket? thank you very much for all the input it has really been helping my journey so far.
RE: 102mm vs 115mm head bolts - starynovy - 03-28-2017
Difference between gaskets is something like 0.2mm total so no.
RE: 102mm vs 115mm head bolts - barrote - 03-29-2017
U have 30 bolts plus 2 m8 . Those 30 6 of them are 115 or what ever they state. Why dont u use the old ones? This is a MB everithing is reusable. Have rhe tolelance checked and use them or not.
RE: 102mm vs 115mm head bolts - AlanMcR - 03-29-2017
(03-29-2017, 02:05 AM)barrote U have 30 bolts plus 2 m8 . Those 30 6 of them are 115 or what ever they state. Why dont u use the old ones? This is a MB everithing is reusable. Have rhe tolelance checked and use them or not.
The EPC lists how many of each length are needed. They are stretch bolts, and they do permanently stretch when installed. The factory lists these specs:
Length when new: 102/115mm
Max length: 104/117mm
In practice, when I've measured bolts taken out of an OM606, the used bolts were at or beyond the max length. Also the threads were noticeably distorted. The thread pitch was lower in the part of the bolt that didn't engage in the threads in the block. This would lead to incorrect torque if re-used.
SUMMARY: DON'T REUSE STRETCH BOLTS.
RE: 102mm vs 115mm head bolts - barrote - 03-30-2017
there we have another myth....
RE: 102mm vs 115mm head bolts - starynovy - 04-01-2017
Well then someone fucked those bolts by not obeying tightening sequence. We measured bolts from 606turbo with 1 milion km on it and they were like new. Reused twice, still holds and measures the same.
RE: 102mm vs 115mm head bolts - barrote - 04-01-2017
The myth is questionable then...
RE: 102mm vs 115mm head bolts - AlanMcR - 04-01-2017
If the bolts haven't stretched they were not installed correctly. That is the whole point of this type of fastener. They are cheap anyway.
RE: 102mm vs 115mm head bolts - barrote - 04-02-2017
The principle behind strech bolts is the elasticity principle of stell.
Wich is afected by heating cycles..... and after some 50.000 heating cycles, more or less one milion km,(i´m guessing) the must be able to still maintain its elasticity principle. The MB repair manual states 2 kinds of bolts, common bolt and strech type, measure them to avoid going too deep in well, and tight against the bottom instead of the walls (threads). (or in some cases of extreme distortion/strech they may no longuer be in condition to be used again)
But anyway is a myth, and myths are what they are
RE: 102mm vs 115mm head bolts - atypicalguy - 04-02-2017
(04-02-2017, 04:37 AM)barrote The principle behind strech bolts is the elasticity principle of stell.
Wich is afected by heating cycles..... and after some 50.000 heating cycles, more or less one milion km,(i´m guessing) the must be able to still maintain its elasticity principle. The MB repair manual states 2 kinds of bolts, common bolt and strech type, measure them to avoid going too deep in well, and tight against the bottom instead of the walls (threads). (or in some cases of extreme distortion/strech they may no longuer be in condition to be used again)
But anyway is a myth, and myths are what they are
I checked the 617 bolts. The new ones were dedefinitely shorter and the old ones were variable length.
I believe they changed from no-stretch to stretch fasteners during the yyears of 617 manufacturing. The bolt heads are different. So it depends what year the block is. I specified this when ordering the parts.
RE: 102mm vs 115mm head bolts - barrote - 04-02-2017
Regarding MB´s I only know one thing, after the 60´s untill the apearence of euro6 rules the "philisophy" was repairable production, with spares on condition, even gaskets and O rings are of such nature that they were made to use on condition.
If one read carefully, the repair manual states very often tolerances, the idea is for the user to choose wiselly weather to use new or used.
anyway there are always myth´s so as rings and so on...
RE: 102mm vs 115mm head bolts - AlanMcR - 04-03-2017
Here are the cylinder head bolt pages from the MB manual (attached PDF). These pages assume that you are using the factory multi-layer steel headgasket.
List of bolts, Tightening pattern, Length limits, How to measure.
RE: 102mm vs 115mm head bolts - barrote - 04-03-2017
I could read "if bolt excedd X measure use new bolts".
Wich cames to mind the Myth thing again
But i don't have any dought...
RE: 102mm vs 115mm head bolts - atypicalguy - 04-03-2017
(04-03-2017, 01:49 PM)barrote I could read "if bolt excedd X measure use new bolts".
Wich cames to mind the Myth thing again
But i don't have any dought...
I am not sure I understand you. The manual says exactly that: if the bolt is longer than 117mm, use a new one.
You can tell the bolts are designed to stretch because the manual specifies an angle of rotation for the final two stages. You torque it, then rotate 90 degrees to stretch a bit, then wait for it to stretch 10 min, then rotate it another 90 degrees to put the final stretch on it.
RE: 102mm vs 115mm head bolts - barrote - 04-04-2017
I do understand that. Always did. Some fellas don't... then the myth thing.
got me now?
RE: 102mm vs 115mm head bolts - Evgeniy1987 - 04-04-2017
(04-03-2017, 09:17 PM)atypicalguy(04-03-2017, 01:49 PM)barrote I could read "if bolt excedd X measure use new bolts".
Wich cames to mind the Myth thing again
But i don't have any dought...
I am not sure I understand you. The manual says exactly that: if the bolt is longer than 117mm, use a new one.
You can tell the bolts are designed to stretch because the manual specifies an angle of rotation for the final two stages. You torque it, then rotate 90 degrees to stretch a bit, then wait for it to stretch 10 min, then rotate it another 90 degrees to put the final stretch on it.
May I disagree on that one, please?
The fact that they prescribe a certain angle is because an angle is by definition more precise than a torque, because the total torque is an add up of bolt stretch and frictions: friction in threads and friction at bolt head contact area.
A certain stretch force ( = force that holds the head against the block) is reached by a certain stretch of the bolt.
An angle is a direct conversible measure for stretch, while torque is not...
Then there is something like "necessity of precision" or something: they could also say like "torque to 130 Nm".. but because of earlies described reasons, this torque may cause to few bolt stretch, which then causes to few force. Even worse: different per bolt..
I therefore disagree, that the statement "rotate 90 degrees" automatically implies stretch 1-time-use bolts. It can be done for precision reasons.
RE: 102mm vs 115mm head bolts - barrote - 04-04-2017
So the myth goes on and on
RE: 102mm vs 115mm head bolts - atypicalguy - 04-04-2017
(04-04-2017, 05:59 AM)Evgeniy1987Thanks but I think you are agreeing with what I wrote, not disagreeing.(04-03-2017, 09:17 PM)atypicalguy(04-03-2017, 01:49 PM)barrote I could read "if bolt excedd X measure use new bolts".
Wich cames to mind the Myth thing again
But i don't have any dought...
I am not sure I understand you. The manual says exactly that: if the bolt is longer than 117mm, use a new one.
You can tell the bolts are designed to stretch because the manual specifies an angle of rotation for the final two stages. You torque it, then rotate 90 degrees to stretch a bit, then wait for it to stretch 10 min, then rotate it another 90 degrees to put the final stretch on it.
May I disagree on that one, please?
The fact that they prescribe a certain angle is because an angle is by definition more precise than a torque, because the total torque is an add up of bolt stretch and frictions: friction in threads and friction at bolt head contact area.
A certain stretch force ( = force that holds the head against the block) is reached by a certain stretch of the bolt.
An angle is a direct conversible measure for stretch, while torque is not...
Then there is something like "necessity of precision" or something: they could also say like "torque to 130 Nm".. but because of earlies described reasons, this torque may cause to few bolt stretch, which then causes to few force. Even worse: different per bolt..
I therefore disagree, that the statement "rotate 90 degrees" automatically implies stretch 1-time-use bolts. It can be done for precision reasons.
I only said the angle means that the bolt stretches. I did not say it was a single use bolt. They may be reused if they are within the specification in the manual page supplied above.
RE: 102mm vs 115mm head bolts - Evgeniy1987 - 04-04-2017
(04-04-2017, 10:29 AM)atypicalguy(04-04-2017, 05:59 AM)Evgeniy1987Thanks but I think you are agreeing with what I wrote, not disagreeing.(04-03-2017, 09:17 PM)atypicalguy I am not sure I understand you. The manual says exactly that: if the bolt is longer than 117mm, use a new one.
You can tell the bolts are designed to stretch because the manual specifies an angle of rotation for the final two stages. You torque it, then rotate 90 degrees to stretch a bit, then wait for it to stretch 10 min, then rotate it another 90 degrees to put the final stretch on it.
May I disagree on that one, please?
The fact that they prescribe a certain angle is because an angle is by definition more precise than a torque, because the total torque is an add up of bolt stretch and frictions: friction in threads and friction at bolt head contact area.
A certain stretch force ( = force that holds the head against the block) is reached by a certain stretch of the bolt.
An angle is a direct conversible measure for stretch, while torque is not...
Then there is something like "necessity of precision" or something: they could also say like "torque to 130 Nm".. but because of earlies described reasons, this torque may cause to few bolt stretch, which then causes to few force. Even worse: different per bolt..
I therefore disagree, that the statement "rotate 90 degrees" automatically implies stretch 1-time-use bolts. It can be done for precision reasons.
I only said the angle means that the bolt stretches. I did not say it was a single use bolt. They may be reused if they are within the specification in the manual page supplied above.
Hmm... I should to read better
you are right! 
RE: 102mm vs 115mm head bolts - BoostedW124 - 04-21-2017
I am wrapping up my head gasket aka glow plug gone wrong ordeal. So on Om606 we have 26 total serrated 10mm head bolts. 20 are short 102mm and 6 are long 115mm. Oiled bolts with clean threads in block are important as well as clean prepped surfaces. I took apart 2 606 heads this month, my turbo 606 and an na 606. I purchased new Victor reinz head bolts just because everyone says safe then sorry... but i did micrometer and also visually compare these to the original MB bolts for curiosity sake and they were dam close to each other and totally all in spec no where near 2mm stretch. These bolts are incredibly durable even the serrated triple square head resists stripping/rounding. The last 90 degree turns had me sweating taking my time because boy do they get TIGHT! Have injectors and lines to attach tomorrow as well as buy fluids i will crank this sucker over. My 2 cents is that i saved all my extra headbolts and on my next future head gasket job i will reuse these. I believe these bolts do stretch under the tension against the head but upon removal they retain their elasticity of sorts and go back very close to their natural length...
RE: 102mm vs 115mm head bolts - barrote - 04-22-2017
Thats what people have been telling u since beggining
Measure and install if in spec size.