As there is no warning indicator for a worn timing chain and there is no change interval for this chain, you should never ignore noise or other symptoms which could indicate a worn timing chain during a visit to the garage. After all, a new timing chain is cheaper than a new engine.
Common indications of a worn chain are, apart from noise, also a lack of engine power. In petrol engines without turbo, this is usually the only warning you receive. It is worth recalling that only a few degrees of dephasing between crankshaft and camshaft affect the suction power of the engine and thus reduce the performance significantly. Do not ignore fault codes for camshaft sensor or an abnormal manifold pressure. This type of fault codes, possibly combined with MIL turned on, may be the final warning before a potential chain failure.
Therefore, we recommend:
Unfortunately, there is no data for wear limits or how far the travel can be in the chain tensioner.
Therefore, wear in timing chains is often missed or ignored, right until the damage is done.
The inner friction of the engine is an important factor for the fuel consumption and thus the emission.
The hunt for lower fuel consumption has entailed many interesting solutions but has possibly also caused problems.
This example is from 1.2 and 1.4 engines from VW..