Timing Chain Stretch
Symptoms
Rattling or slapping noise from the front of the engine, particularly on cold start. The noise may diminish as the engine warms but does not fully disappear.
Cause
The L-series uses a single-row timing chain (on early engines) or double-row chain (later engines) with a hydraulic chain tensioner. Over time, the chain stretches and the tensioner guides wear. The tensioner compensates up to a point, but eventually the chain becomes excessively loose.
Fix
Replace the timing chain, tensioner, and guides.
A double-row chain conversion kit is available for single-row engines ($200-400) and is strongly recommended.
The job requires removing the radiator, fan, and timing cover.
It is a full day's work but well within the ability of a home mechanic.
Do not ignore excessive chain noise, a severely stretched chain can jump a tooth, causing valve timing to shift and potentially causing valve-to-piston contact.
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