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Do main bolts have to be replaced?
by
rallydiesel
on 09 Aug, 2007 09:18
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I am doing an engine overhaul and need to know if the main bolts need to be replaced. The manual says they aren't stretch bolts. I know the rod bolts need to be replaced.
Thanks for any help.
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#1
by
zukgod1
on 09 Aug, 2007 09:30
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I've never heard the rod bolts need to be replaced.
I'm sure it's a good idea to replace all fasteners but just the same, never heard of it.
Dan
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#2
by
rallydiesel
on 09 Aug, 2007 09:53
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According to Bentley's, the rod bolts are stretch bolts. That's all I know. :?:
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#3
by
jtanguay
on 09 Aug, 2007 09:59
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well i would assume that any stretch bolts should be replaced. the bentley should say whether or not they need to be replaced...
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#4
by
zukgod1
on 09 Aug, 2007 10:18
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Somebody bust out a book and tell us please?
I JUST reassembled my bottom end and dont want to button it up if those things are supose to be replaced....
I'm at work, that really doesnt matter, I've not recieved my book yet anyway
dan
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#5
by
Barry W
on 09 Aug, 2007 20:13
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All factory rod bolts are stretch bolts. Replace them and save losing a rod!
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#6
by
A2TD
on 10 Aug, 2007 11:01
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All factory rod bolts are stretch bolts. Replace them and save losing a rod!
Actually there were some applications where they did not use stretch bolts on the mains, the bently actually talks about this, if the bolt you took out is threaded all the way to the head of the bolt, its a stretch bolt, if the bolt is only half threaded it is not a stretch bolt......
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#7
by
zukgod1
on 10 Aug, 2007 11:24
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All factory rod bolts are stretch bolts. Replace them and save losing a rod!
Actually there were some applications where they did not use stretch bolts on the mains, the bently actually talks about this, if the bolt you took out is threaded all the way to the head of the bolt, its a stretch bolt, if the bolt is only half threaded it is not a stretch bolt......
Ok, that's good to know. Now I just wish I had payed attention to that when assembling the bottom end. At least it's still on the stand.
dan
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#8
by
jtanguay
on 10 Aug, 2007 12:38
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yea.. i never took that into consideration when rebuilding my bottom end either.
i'm guessing TDI's have stretch... oh well at least it's still open and accessible.
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#9
by
clbanman
on 11 Aug, 2007 04:58
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My Bentley covers 1985 to 1992, and the only internal engine bolts that it specifies replacing are the head bolts.
I don't know about VW, but stretch bolts as a rule are not always threaded to the head. Often they will have a necked down section on the shoulder. Also, a clue to bolts being stretch bolts is that the torque specification will give you a torque value, and then specify an additional angular turn dimension. "Stretch" is a bit of a misnomer as all bolts stretch when torqued to the proper value. This is what keeps the bolt from loosening. The idea is that the bolt stretches far enough that the forces in tension are higher than any the bolt will see in shear or torsion but still sufficiently below the elastic limit in tension. What we normally call stretch bolts are single use bolts that have been designed to stretch closer to their elastic limit.
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#10
by
rallydiesel
on 18 Aug, 2007 06:49
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Yes, and my Bentley says to torque them "x" amount plus "x" degrees more. Therefore they are single-use bolts. I am replacing mine because I don't want my time and money going to waste when a rod destroys my bottom end.
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#11
by
zukgod1
on 25 Sep, 2007 12:12
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Old thread, where can we get some good rod bolts? ARP?
dan
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#12
by
dillenger1
on 27 Feb, 2008 18:23
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I thought this was funny,because my Chilton manual(sorry)specifies two different types of rod bolts used(stretch and non)It says the non -stretch reusable rod bolts will have notches on the nuts.It shows a picture of the nut that needs replaced and every flat on the nut has a small notch machined/forged into it.
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#13
by
jtanguay
on 27 Feb, 2008 18:31
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imho stretch bolts aren't too expensive, and since its not every day that one tears into their engines... you might as well replace them and avoid rod failures (which will destroy the block)
for ARP stuff someone posted some part numbers. possibly in the FAQ?
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#14
by
dillenger1
on 29 Feb, 2008 19:43
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What i was trying to say is it seems i have reusable rod bolts.My chilton says that if the nuts have notches on the flats then they need replacing,if they dont then your ok to reuse them.