1994-2002 [Subscribe to Daily Digest] |
Members do not see ads below this line. - Help Keep This Site Online - Signup
Apparently us NG 9-3 owners have a recurring headache to deal with - routine retorqing of the deficient headbolts. Out of the dozens of cars I have had over the years and hundreds of problems, this one gives me some concern. As I consider retorqing the headbolts on my 00 9-3 SE for the first time at 63k I gave it some thought because of all the postings I have seen on this topic recently. Maybe more thought than I should...
1.) First of all, it is clear the bolts were either a) not properly tightened at the factory, or b)of deficient material or design for the task at hand. Saab left us a mess on this one.
2.) The service bulletins issed by Saab and the recommendations by many of us here may be leading us down a risky path. Simply retorquing (actually restreching) the existing head bolts is a bit more complicated than it sounds. These are torque-to-yield (TTY)type bolts in this application. TTY bolts are designed to stretch slightly when tightened to provide more consistent clamping force. When a bolt is streched some permananent level of deformation takes place as well as a slight increase in length. Nothing is stated about using new bolts everytime a retorque is performed. But reusing them increases the risk of breakage. A stretched bolt may also not hold the same torque load as before, which may cause a loss of clamping force resulting in head gasket leakage, breakage of one or more head bolts as well as potential for warping of the head. Bottom line is new bolts should probably be used vs. merely retorquing old bolts.
3). There seems to be no concensus on how often this has to be done, the interval could be as short as several hundred miles of operation before things get out of whack again. 10k, 50k intervals, who knows??? By the time we get around to retorquing them, the head may already have seen a degree of warpage.
Saab (or more appropriately, Saab owners) did not have this problem with early NG 900 bolts, it was a change in 1997 or thereabouts to a different bolt type and/or factory technique in tightening that gave us this hangover. This could result in a lot of blown head gaskets and expensive repairs for the consumer and their TSBs on the topic do not address the issue adequately.
posted by 24.236.8...
, Thu, 23 Dec 2004 17:35:47, Thu, 23 Dec 2004 12:32:19
, Thu, 23 Dec 2004 19:05:18, Thu, 23 Dec 2004 21:32:56, Fri, 24 Dec 2004 09:17:02
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
