The timing chain tensioner on GM’s 2.3L "Quad 4" engine is of the spring loaded ratchet design. The tensioner assembly consists of a housing, spring, and ratcheting plunger. The plunger is locked into the housing and plunger to prevent the accidental release of the spring before or during installation.
Once the tensioner is installed and the chain is in place, the anti-release device must be removed and the plunger manually depressed into the housing to unlock the plunger and release spring tension on the chain.
Failure to perform this important final step can lead to severe engine damage.
–Tech Tip courtesy of MAHLE Clevite