2002 Tundra 4.7 jumped timing belt, cause unknown

Hi everyone, I'm new to this forum but thought I should post because I experienced something pretty strange. Searched all I could and found nothing similar so here goes.

2002 Tundra 4.7 V8 2wd AC with 305,000km on the clock. Bought it 6 months ago for $6,200 bucks. Well looked after, no rust, timing belt done at 295,000 and it's been running great since purchase. Light duty use. Heaviest loads were gravel and soil for a ten minute drive in May.

Last week while stopped at a 4 way the revs suddenly dropped to 500 and had a really really rough idle. I drove about a block with it running super rough then pulled over and parked at the nearest safe spot. Tried shutting it off and restarting but idled rough at 500 then stalled. Couldn't get it started again, just crank with no start. Spent the next few days trying to diagnose the problem with no joy. Had fuel, air and spark, though weak. When I pulled a plug it was covered in fuel. Finally threw in the towel and had it towed to the garage.

The garage found that the timing was totally out, but the belt wasn't broken or missing any teeth. Total surprise to me because the timing belt and water pump etc had been replaced less than 10k ago by previous owner and had been running beautifully. They found the belt in perfect shape, tensioner working correctly, all cams and pulleys turning fine, water pump pulley turning fine. Said that the timing belt had "jumped" but couldn't find a reason why. They reset the timing using the old parts and the truck ran fine. Luckily no valve damage. Didn't recommend replacing any parts. I paid the bill and drove it home (hard) and bought a lottery ticket.

Has anyone else experienced something like this? Anybody have any ideas why a timing belt would jump?

 

Do you know if the belt was mitsuboshi? (Not a typo, also may not be spelled correctly. Also, not Mitsubishi.)

 

No idea what the belt brand is. Are they known to have issues?

 

Mitsuboshi brand belts come in the aisin timing belt kits. OEM supplier of parts for Toyota back in the day, and currently

 

Here's the info for the kit on RA. Read on.
https://www.rockauto.com/en/moreinfo.php?pk=3290529&cc=1357938&pt=16088

 

Did they notice anything weird at the bottom of the engine where the timing belt wraps around the crank? The 3.0L V6 in my 1993 T100 turned into a meat grinder when a rat got into that area. Jumped timing and the engine ran really rough at idle. Had rat hamburger all over the timing belt.

 

Had a Tacoma 5vz do something similar once, not a 2uz, but very similar engine design.

Truck has sat for 6-8 months before I decided to put it back into service. I put a new clutch in it and changed the oil, and it drove great for a few short trips.

Awesome. I'll get a tank of fuel and get an inspection on the way back so I can renew the registration.

orrrr not

Upon startup after filling up it was running like absolute garbage. Limped it home and tore into it to discover the water pump had developed a leak prior to parking it and the coolant crusties combined with the lubrication of the fresh coolant had caused the timing belt to jump 2 teeth. That's my theory anyway. Honestly pretty impressed it drove as well as it did. Did the Timing belt, tensioner, water pump, and all the related goodies and it hasn't skipped a beat since. My old man drives it now 3-4 days a week.

 

Shifting from Neutral, into reverse, while rolling backwards can do it. (on some cars at least)

 

Yummy.

No, no rat burger that I can see....or smell.