I did a search but did not find an answer, what mileage on the 5.4 is it recommend to change the timing chains on our trucks ?

 

No specified interval, they usually last the life of the engine..

 

There is no recommended interval for the timing chain. It is designed to last the life of the engine. However, they do stretch over time and throw the cam timing off a little. Old-school thinking was 100,000 miles for optimum efficiency.

Realistically, the truck would be a rolling bucket of rust by the time you break a timing chain. If you break one ever.

Long story short, don't worry about it unless it breaks. If you have the 5.4L, wait until you have a cam phaser failure if you want to replace the timing chains.

 

The chain tensioner and guides will fail before the chain itself and as the other poster stated the phasers will probably fail before anything else. When you change the phasers it would be smart to change the chains and guides at the same time.