2008=100K MILES-When shold the serpentine belt be replaced?

In the maintenance guide, I see it popping up for inspection at 60,000 and then every 15,000 after that. No mention of replacement out to at least 255,000 miles, so I assume you just replace it as soon as you see any cracking or other signs of wear or damage. I replaced mine at about 115,000.

 

Immediately. If it fails and falls off you’ll never know till the check engine light or the RTOD lights up,
Overheated motor which sometimes results in blown head gasket.

 

The fact that you are talking about it is enough to change it and get it off your list and move on.

 

Change it now. Its a combination of miles and actual service life or age that eventually claim the life of a belt. It's a $15 belt from Mother Toyota, less if you go aftermarket, and you really don't have to smash atoms to R&R it. I would also encourage your neighbor to get a new tensioner pulley and bolt as removing the exiting one can prove to be problematic. A new pulley and bolt is $50 from Mother Toyota. Good luck.

 

That belt has no load on it to speak of. Unlike a a traditional Alternator/ A/C/ power steering power belt. I wouldn’t worry about it, unless the water pump needs replacement. Then you just replace it because you’re already in there.


iPhone X ?

 

Yeah, it's lightly loaded. I would not change it unless it was cracked. Then, don't dilly-dally because you really don't want it to break. And with that many miles, I'd be surprised if it isn't cracked quite a bit, unless someone already changed it

 

For $15, hardly worth debating, lol. That's like the PCV valve: cheap as dirt to replace. Don't use an open wrench on those, btw: can crack the valve cover when it breaks lose.