Trapped at home because of the virus figured I'd get some maintenance done.

Changed today with another gates, pics of old belt below.
Looks like it could've gone a lot longer LOL
Old one stretched maybe half an inch longer than the new belt.

I do periodic visual checks of the belt every oil change and was wondering why there was not much sign of wear.

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Agreed - im also on here bc of downtime.

I visually inspect mine regularly, but the wear on each one is different. Like suspension theres no definite need to change it at certain mileage

That belt held up remarkably well for 138K miles of service. Way to go, Gates!

I just did a full maintenance at 130K miles that included radiator, water pump, t-stat, hoses, pulleys and serpentine belt. None of the old parts looked anywhere near failure, really did it out of an abundance of caution and that fact the vehicle is now 17 years old. The serpentine belt looked just like the one pictured. I don't know if they fail by chunking out teeth like a timing belt often does or if they develop lots of cracks on the underside and separate but mine wasn't doing either.

I installed a Delco belt and it's failing after about a month's use. I heard some knocking from the engine and it was a piece of the edge of the belt that has separated.

The old one was fine, had ~160,000 miles on it so I figured a new one would be safer. Did I just get a bad belt? Should I have replaced the tensioner too?

i don't replace mine until it starts squeaking. i always have a spare zip tied inside the engine compartment just in case it snaps while i'm far away from home.

Trying to find the right belt for my 2006 4Runner, bought a gates heavy duty serpentine belt from rockauto.com and it was too long but when I went to look at their website after its arrival they didn't have it listed anymore. Has anyone used the Gates FleetRunner Micro-V serpentine belt part #: K070835HD or do yall use the Gates Micro-V part #: K070835. Both say they will fit according to the website catalogue just don't want to waste money if the HD isn't going to fit correctly.

Just found a Gates standard replacement belt on rockauto with part #: K070834 difference is effective length = 83.39" outside circumference = 83.96" compared to both Gates belts part #: K070835/HD with effective lengths = 83.46" and outside circumferences = 84.03"

Depends on what the belt is made of, that one looks a little glazed but not too bad. I've noticed on the aftermarket belts they're a bit more plastic feeling/ looking, when they wear they get rather glazed and a bit harder/shinier? (Can't seem to find the right descriptor...) makes me wonder if they use a similar material to timing belts which can look good even though they're worn.. They will usually start developing small cracks that become more obvious over time perpendicular to the ribs, I've seen a couple with missing chunks, but not often. The factory ones seem to stay more supple feeling even after a long time and with cracks in them.

Something entertaining if you're bored is running a pick through the grooves and seeing how many ground up rocks and such get embedded in those belts.

OEM for ~$41 here if you're interested. I ran the search for my 2007 4R so you may want to confirm it's the same part number, though I can't imagine it being different if you have the V6.