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Re: do timing chains strech or is it usually worn guides? Posted by Gene N [Email] (#1094) [Profile/Gallery] (more from Gene N) on Wed, 12 Feb 2014 04:52:41 In Reply to: Re: do timing chains strech or is it usually worn guides?, Stephen Goldberger, Tue, 11 Feb 2014 07:49:40 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Well, one of the definitions of stretch is to lengthen, which is certainly the case here, but I get your point. The chain is not getting longer because the stress on the link material has reached its elastic limit and the link has permanently deformed. Instead, the pivot point hole in the link is wearing allowing the roller to be displaced slightly, which if multiplied by a 100 links, adds up to a chain that is both longer and noisier because of the additional movement of the pivot.
I had a 1991 9000 that snapped its timing chain at about 100K miles (6 bent valves). When I compared the broken chain to the new chain, I was surprised to find that the old chain was of the split roller variety, i.e., the rollers looked like grove pins. The rollers on the new chain were solid like every other chain I had ever seen.
Both the new and old chains on the 9-5 were solid rollers, so I can only guess that the general lubrication problems associated with the early 9-5 4-cylinder models contributed to the unusual wear.
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