Measure timing chain tensioner extension / timing chain wear - Saab 9-5 Bulletin Board - Saabnet.com
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WIS gives a complete description of how to evaluate TC wear by measuring TC tensioner extension. So check WIS on line for details.
I am including a link to WIS on line TC tensioner replacement. The main thing is that there is a 12mm cap screw in the back of the tensioner, which holds in a spring and a small plastic plunger. It is sealed by an O-ring. DO NOT LOSE the 12mm bolt, the O-ring, the SPRING, or the PLUNGER, because these last two only come with a complete tensioner ! There is a ratchet mechanism that keeps the tensioner from backing up.
The tensioner is primarily held by hydraulic pressure from engine oil and the ratchet, but the spring assists. You want to know how extended the tensioner is when it's working, so you remove the 12mm bolt and the Spring, and make sure not to dump the plunger when you remove the tensioner itself. Use a deep 27mm socket (don't use SAE 'equivalent') passing through the serpentine belt tensioner mounting bracket - some sockets are too short. Sometimes the Plunger comes out with the Spring. With the Spring pressure relieved, the tensioner should stay where it was when operating, and that's how you get the "extension" measurement.
Reinstalling: Use NEW Seal and O-ring, or expect it to leak, maybe a lot. Retract the tensioner by pressing the ratchet arm, install the tensioner with a New Seal, and torque it down. With the Plunger and Spring placed into the tensioner, carefully screw in the 12mm bolt (CAREFUL, if you slip, the Spring might go to places unknown). Loaded like this, the spring extends the tensioner and makes sure there is some pressure on the chain before the oil pressure pushes it out the rest of the way. This is CRITICAL, because if the engine is rotated without a tensioner in place, there might be some real problems.
There is a nice description and pictures on another site if you search "let's roll in a timing chain". The spec limits for the extended TC tensioner is 15mm (from on line version of WIS). You will probably only be interested in reading parts about the tensioner.
Hope this helps.
Mark in Marine
WIS TC Tensioner replacement
->Posting last edited on Fri, 18 Oct 2019 12:54:28.
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