My 97 F150 has 128,000 miles on it and has been running very well, but I am wondering what is the recommend mileage that the timing chains on a 5.4 should be replaced at?

 

They *should* last the life of the engine.

 

Whenever the engine blows up. My dad's '97 F250 has 195K-something on the original chains, guides, etc. Replace 'em whenever the engine gives up.

 

If it's not broke,,,,don't fix it!

Phil

 

I have disassembled many 4.6 engines with over 300,000 miles not counting idle time and the chains were like new. Discolored from the oil and crankcase deposits but mechanicly like new! We basicly never see the timing chains fail unless you lose oil pressure and start to seize a camshaft. I wouldn't worry about the chains. Like someone said above they last the lifetime of the engine.

 

This engine is not a Triumph V8 'cause on that you were lucky to get 25k out of a set! British Leyland!!! I did love the car mind.........

 

320,000 miles on my original chains and guides in the original untouched engine. My truck sees wide open throttle upshifts in first and second gear almost every day. At 128,000 I'd say yours are just broken in.