[V6-12v] More on V6 Head Bolt re-torque

[Elliott Potter]

I won't speculate on the particulars of how much to turn the bolts, but
I found 1/2" drive sockets for both styles of head bolts at NAPA for
pretty cheap.  I definitely wouldn't try to twist them without the
proper socket.
--
Elliott

On Sun, 12 Sep 2004, apowell at colocougs.org wrote:

> I have the valve covers off my 1993 90Q V6 (2.8L), with the intention of tightening the head bolts
> 1/4 turn as directed in the factory manual after removing and replacing the intake manifold.
>
> Two problems:
>
> 1) The bolt heads are only about 11 MM, and they are not octagonal. They are star-shaped. I don't
> have a socket to match these heads.  Anyone know whether this bolt head design has a specific name
> (ala Torx or other distinguishing ID) to help me find the correct socket? Also, any idea where I
> might buy a socket designed for these bolt heads?
>
> 2) The factory torque spec on these bolts is 44 lbs/ft. Compared to the torque on US V8 motors, this
> seems like pretty light torque to me (even the head bolts on my 1958 Fiat 1200 with aluminum head
> torqued to 58 lbs/ft). However, I gently tried tightening them with a half-inch drive breaker bar
> (despite my concern voiced in #1) and they do NOT want to budge. I'm EXTREMELY reluctant to put a
> lot of torque on these, and I'm sure I tried at least 60 lbs/ft without moving them a bit. What's
> going on??? I know they might have to break loose, but this seems like a lot of torque for bolts
> spec'd at 44 lbs/ft. If I turn them 1/4 turn, based on the force I already used, my guess is that
> after another 1/4 turn those bolts will be torqued to around 100 lbs/ft. I'm afraid the heads will
> shear off at that torque.
>
> Has anyone BTDT with this procedure?
>
> I received contradictory comments about how to go about tightening the bolts on these heads. One
> lister suggested I should break them loose, then re-torque to factory torque plus 1/4 turn. Others
> noted that these are "stretch" bolts and are intended for one-time use, so I should just turn then
> 1/4 turn, which is the process as per the factory manual. It seems to me that if the bolts are
> designed for one-time use, I should NOT loosen them and then re-tighten them. Heck, one lister
> suggested I turn them 1/2 turn! That would put them at 150 lbs/ft or more, which makes no sense.
>
> I decided to leave it parked until I can find an appropriate socket for the bolt heads AND figure
> out what to do.
>
> Would the best move be to buy new bolts and replace them one by one in each head so that I know I
> won't have any problem with them? Or should I get the socket and turn them another 1/4 turn?
>
> ************************************
> Al Powell
> apowell at gocougs.wsu.edu
> 1958 Fiat 1200 Transformabile Spyder
> 1983 Datsun 280ZX Turbo
> 1993 Audi 90Q
> 1997 Chebby Blazer
> 1999 Chebby Blazer
> ************************************
>
>
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