Date: Fri, 14 Mar 2003 15:14:49 -0500 From: 'nuther Bob <noemailnopsammain.com> Subject: Re: Loose cilinder head bolts a common problem?
On Thu, 13 Mar 2003 20:56:49 +0000, Grunff <grunffnopsam.com> wrote: >Fred W. wrote: > >Head bolts don't loosen themselves - it just doesn't happen that >way. And as Fred said, they're only supposed to be used once, >because they stretch as part of the initial torqueing. What your >garage did is dubious at best. Start saving up. A few comments... This was common on the NG900. Some time around late 97 they issued new torque specs that actually had _lower_ settings than previously. They theory is that the head gasket "wears" as the iron block and the aluminum head expand and contract at different rates. Therefore by tightening them less, the wear is reduced. On my own NG900, I checked the bolts. Sure enough, there was a rather loose one, and the corner where everyone's gaskets leak. Another was somewhat loose. We're talking a bolt with maybe 40lbs that has a rec. setting around 80lbs. So, why would it be loose ? Could the gasket wear more in one spot ? Could the factory have left that bolt looser that others year after year ? Doesn't seem likely, but it's a common issue and there must be some reason. Bad bolts maybe ? Back to the bolts. I know that a lot of cars have head bolts that are only supposed to be used once. However, try as I might, I could not find any reference to this in any repair manual for the 2.0 motor. The bolts do have a three stage torque process with something like 40/80/ turn 90 degrees. I did retorque mine. It did not seem like the best idea, but having them loose didn't seem so good either. I did not use the factory torque settings since I assumed that the bolts has already stretched although I did use their pattern and brought them up in three stages to the last torque settings. FWIW, all were looser that the specific final torque before the 90 degree turn. Bob
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