My official answer would have to be......
"it depends"
Some applications use TTY (torque to yield) bolts. They are designed
to be torqued to a specific value and then turned some x amount of a
turn further. This extra turn actually stretches the bolts a specific
amount, imparting an additional amount of clamping force. The
downside to these is that they can only be used once.
The turbo Buick V-6's used these and there has been a great amount of
debate on the gnttype list over the years regarding the re-use of TTY
headbolts. Some people have been able to re-use them without failure,
but the overwhelming majority of people who have tried to re-use them
have had failures.
If TTY is mentioned anywhere in the FSM, then I would say do NOT
re-use them. If it is not mentioned, then I would go ahead and re-use
them only after chasing the threads like Bernd said. As an addendum
to this, I would only re-use head bolts once or twice. After that,
it's cheap insurance to go for the ARPs.
Also, when torqueing the head bolts, you should be able to feel if the
bolts are stretching abnormally. It's that sickly feeling you get
just before the bolt snaps!!!
P.S. Bernd, did you ever hear from your buddy on the RT list about
the electric fan mod we talked about?
Tom Lorek
'00 Durango 5.9 SLT+ 4x4
'99 Concorde LXi
'87 Buick GN 10.52 @ 127.5 ( back in 1992)
On Mon, 30 Apr 2001 13:06:39 -0400, bernd@texas.net wrote:
>
>On stock applications, it "ok" to reuse headbolts...but they need to be cleaned
>and the threads "chased" (cleaned) for proper TQ readings. On any type of
>modified (Supercharged especially) rework...use NEW bolts. Preferred is ARP
>Studs.
>
>Again, don't forget to run a thread chaser on the head bolt holes (on the
>block) before installing the new bolts.
>
>- Bernd
>
>> My understanding is that when you torque them down they stretch a bit and
>> that's normal. You can't stretch them again.
>>
>> I would ask Bernd and go with what he says.
>>
>> ----- Original Message -----
>> From: "Wisotzkey, Rich" <Rich.Wisotzkey@gd-wts.com>
>> To: <dakota-truck@buffnet.net>
>> Sent: Monday, April 30, 2001 9:21 AM
>> Subject: DML: RE: Re: F*** :) What's the deal?
>>
>>
>> > Please don't tell me you can't reuse the head bolts!!! The manual doesn't
>> > mention replacing them. I wasn't sure about this and ask the service
>> people
>> > at the dealership. They said they reuse them all the time, and I didn't
>> > need new ones. Now I have the engine just about all buttoned up. Should
>> > they be changed or not?
>> > Rich - Ashburn, VA
>> >
>> > -----Original Message-----
>> > From: WOT or waiting at a Red [mailto:dakatack@home.com]
>> > Sent: Monday, April 30, 2001 10:56 AM
>> > To: dakota-truck@buffnet.net
>> > Subject: DML: Re: F*** :)
>> >
>> >
>> > Tim
>> >
>> > Did you reuse the old head bolts? If you did, shame on you.
>> > Never, never, never reuse head bolts. If you got new ones, where did ya
>> get
>> > them and what grade were they.
>> >
>> > Patrick O'Day
>> > 2000 Dakota 4x4, 4.7L, CC
>> > Profile at www.dakota-truck.net/profiles/dakota/Cy9WFjn1QtCYw/profile.htm
>> >
>> >
>> > ----- Original Message -----
>> > From: "Tim Berry" <coolva1@home.com>
>> > To: <dakota-truck@buffnet.net>
>> > Sent: Monday, April 30, 2001 8:36 AM
>> > Subject: DML: F*** :)
>> >
>> >
>> > > Well.. I was puttin on my heads yesterday, (blew headgasket) and was
>> > torqued
>> > > them to 50, then was on the 3rd bolt, first side, workin my way up to
>> 150
>> > > FT/LBS, and SNAP, BAM... head bolt broke, and elbow slammed into the
>> > > truck... My dad got the bolt out, and my elbow still hurts and is still
>> > > swolen (12 hrs later)... (pullin with both hands, and elbo slammed into
>> > > fender, sharp edge too)
>> > >
>> > > I ordered some new bolts... if I have to do this again, I'm callin for
>> > ARP
>> > > studs before I even take the heads off.. that way they will be here :-)
>> > >
>> > >
>> > > Oh well... They should be here tomorrow....
>> > >
>> > > Tim Berry
>> > >
>>
>>
>
>
Tom Lorek
tlorek@yahoo.com
Carmel, IN
'00 PB 5.9 SLT+ Durango
'99 Concorde LXi
'87 GN 10.52 @ 127.5
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