Replacement Timing Chain/Tensioner Longevity Question

[dlimanov]

Thanks @dogfood1!
Does anyone know where the magical model year of 2013 comes from when it comes to updated timing chain components? Because the same engines in L405s are exhibiting timing chain failures all the way to 2015 model year.
Just trying to figure out if it is worth paying premium for 2013 truck vs pre-2013 if in reality either one will require the repair done anyway. The market‘s bad as is with low inventory and inflated prices.

 

[hickersb]

There was a TSB applying to 2010 - late 2012 trucks calling for the replacement of timing chain tensioner and levers if a clicking noise is heard. See this document https://static.nhtsa.gov/odi/tsbs/2015/MC-10104461-9340.pdf

The newer parts have a hardened steel button at the back of the tensioner levers (where the tensione rod contacts the lever) which is supposed to reduce wear.

In terms of later models failing, I think the underlying (and still unresolved) problem is chain stretch caused by excessively long oil change intervals. To be more specific, the chain itself doesn't really "stretch." Rather, dirty oil results in wear between the pins and bushing on each connecting link and results in the pitch of the chain growing. Then that will result in wear on the cam sprockets. Same reason cyclists have to replace a bike chain every couple thousand miles, and end up having to replace the cassette if they don't keep up on replacing the chain.

 

[ktm525]

I think the smaller diameter oil orifices are prone to clogging.