2002 Explorer V6 4.0 - Timing Chain Questions

[Sixonemale]

I have about 187,000 on my engine and it seems to be running great. I've used synthetic oil since 23,000 and have changed the oil on a very regular basis. Since I may be taking it on fairly long trips, my question is "how do you know when the timing chain is starting to wear out?" When my engine is at idle I don't hear a thing, very smooth. Sometimes when I accelerate, not sure if it's the fuel, but sometimes hear a noise that is higher pitched than lower pitched, but does not seem to be a problem. In other words, would I hear strange noise when engine is idling if my timing chain was going bad? Also, about how long do timing chains last? Thanks in advance for all replies

 

[Tyleryac]

You will hear a rattling/clattering noise.

My timing chains went at 113k miles even with oil changes every 3k miles.

 

[Sixonemale]

Will this noise occur at idle or when accelerating? Thanks