reapeated drive belt failures

[jack black]

I'm scratching my head about this. Never had that problem before. Bought used 2007 1.5L Yaris AT in 2013 with 65,000 miles and the maintenance papers indicated changed drive belt by a dealer a year prior near 60,000 miles. Sounded like good news at that time.

We used the car locally till 2021 when a kid took it out of state with like 112,000 miles. It was super reliable up to now and well maintained. Shortly after that belt made lots of noise and it was shredding by the time kid took it to a mechanic. It was replaced, but the mechanic had problems tensioning it correctly and she had to take it back a few time to fix the noise. when she visited home this summer, the belt looked good and tight.

Now, at about 130,000 miles, it suddenly failed and stranded her in freezing weather. She stopped as soon as she saw overheated engine light and got it towed to a mechanic.

This is very frustrating to hear, being far away from the kid. Not to mention expensive for her. I'm thinking she should get a more reliable car now. Is this a design flaw? How can one be sure it doesn't brake again and strand her out of nowhere in very cold weather?

PS: the last mechanic supposedly checked water pump and all the pulleys and saw no other problems.

Thanks for helping!

[bronsin]

No design flaw. I find it hard to believe the mechanics have found nothing wrong with the things driven by the belt. There’s got to be something wrong

[ex-x-fire]

I'd have the harmonic balancer looked at closely, there's a rubber ring between the two main parts. Sometimes the outer part will start to walk off and cause belt misalignment.
Make sure the belt looks straight from pulley to pulley.

[jack black]

Thanks!
I'll check it myself when she visits for Christmas. Hopefully she makes through the long drive.

[sh0rtlife]

i wonder if they have been over tightening things with cheep POS belts...we ALL know these cars love to squeel the belt when cold at times...maybe the monkey with the wrench reeffed on it and overtightened it to the point of failure on a dirt cheep belt

[Compeer]

Never heard of a yari throwing belts.

Serpentine belt problems usually result from one of three causes: a defective belt tensioner; misalignment of a pulley; or, defective bearings in the tensioner, idler, or one of accessories driven by the belt (including the water pump)

This sounds like misalignment to be shredding them or they have been installed way, way to tight.

To check its correct hold the belt between finger and thumb at this point and move it from side to side. See how much it deflects at the centre of the run. If it moves more than 1/2 in. (13 mm) it is too slack - any less movement and it is too tight

[remcafee]

the yaris belt is very sensitive to tension, because its a very small and skinny belt, you need a special tool to tighten in properly and not just wedge a pry bar to the side of the alternator becuase the alternator will be crooked in alignment with the belt

[bronsin]

Youre right they are tricky to adjust. Too loose and they Squeal. Too tight and there goes the water pump.

[IndestructibleYaris]

Never heard of a yari throwing belts.

Serpentine belt problems usually result from one of three causes: a defective belt tensioner; misalignment of a pulley; or, defective bearings in the tensioner, idler, or one of accessories driven by the belt (including the water pump)

This thing doesn't even have a belt tensioner...it is manually tensioned by a hinge bolt and a sweeping slotted bracket that allows you to swing the alternator away and take up slack.

Misalignment of a pulley? There's no way to misalign a pulley. Every single pulley is a critical engine part that is made to tight tolerance.

Defective bearings in the tensioner? You mean alternator?

One of the accessories? You mean either the W.P., Alt., or AC compressor?

It's not the water pump. The pulley drives a shaft which drives an impeller. Not only would you hear the impeller or shaft scraping, but the car would've leaked every drop of coolant before it'd shred a belt from the W.P. bearings being worn out. Every bit of clearance in the bearing is seen by the seals and impeller as well as the pulley.

the yaris belt is very sensitive to tension, because its a very small and skinny belt, you need a special tool to tighten in properly and not just wedge a pry bar to the side of the alternator becuase the alternator will be crooked in alignment with the belt

How? None of this makes any sense. The alternator bolts to the block and a 1/4" thick bracket. Which way are you prying? What makes this car so difficult?

You're right they are tricky to adjust. Too loose and they Squeal. Too tight and there goes the water pump.

Please enlighten me as to how these are tricky to adjust...seems like you know exactly how tight to make them. Squeal=loose. Just right=tighten until not squealing. Am I right?

One of my earlier repairs in my life was rebuilding the alternator around 340k miles and I had to get very familiar with the belt and alternator, and never did I think this job was ever a challenge or a mystery in any way

[sh0rtlife]

Please enlighten me as to how these are tricky to adjust...seems like you know exactly how tight to make them. Squeal=loose. Just right=tighten until not squealing. Am I right?


everything you mentioned is mostly correct except 1 thing....if the alt is pulled TOO TIGHT it WILL flex the slide mount enough to cause a "slight" missalignment.

too tight of an alt causes 2 primary things the pulley to missalign just slightly but its a "3/4" wrapped pulley so that slight bit is under ALOT of friction, but having a belt too tight doubles that effect, and also causes more heat build up on the belt and eventual destruction
the other thing it causes is alot of stresses on the alt bearings and eventually causes premature alt failure

the only other things i can think of to force belt fails is any of the components "not tight" ie a slightly loose AC unit..to which would be "tight" under belt tension but be out of true....also a bent or "walked" harmonic balancer(crank pulley)

[jack black]

Merry Christmas to you all.

I inspected the new belt closely while doing maintenance (oil and ATF change, tire rotation, battery check, and other visual checks). the new belt is good quality: Gates Micro-V and in a great shape. the harmonic balancer is not wobbly and none of the pulleys look misaligned.

the only thing that caught my sight is the water pump pulley is partially smooth and polished and in small part rusty. now, i remember it being more rusty 6 months before with the old belt. i have no idea if it maters. i'll take a picture if i can.

i noticed coolant a bit on a low side, i hope it's not headgasket from the overheating episode.

Thanks everyone!

[remcafee]

This thing doesn't even have a belt tensioner...it is manually tensioned by a hinge bolt and a sweeping slotted bracket that allows you to swing the alternator away and take up slack.

Misalignment of a pulley? There's no way to misalign a pulley. Every single pulley is a critical engine part that is made to tight tolerance.

Defective bearings in the tensioner? You mean alternator?

One of the accessories? You mean either the W.P., Alt., or AC compressor?

It's not the water pump. The pulley drives a shaft which drives an impeller. Not only would you hear the impeller or shaft scraping, but the car would've leaked every drop of coolant before it'd shred a belt from the W.P. bearings being worn out. Every bit of clearance in the bearing is seen by the seals and impeller as well as the pulley.



How? None of this makes any sense. The alternator bolts to the block and a 1/4" thick bracket. Which way are you prying? What makes this car so difficult?



Please enlighten me as to how these are tricky to adjust...seems like you know exactly how tight to make them. Squeal=loose. Just right=tighten until not squealing. Am I right?

One of my earlier repairs in my life was rebuilding the alternator around 340k miles and I had to get very familiar with the belt and alternator, and never did I think this job was ever a challenge or a mystery in any way

you can absolutely make the alternator crooked, go adjust your belt tension and tighten it really tight and watch the alignment of pulley with the rest of the accessories

[sh0rtlife]

Merry Christmas to you all.

I inspected the new belt closely while doing maintenance (oil and ATF change, tire rotation, battery check, and other visual checks). the new belt is good quality: Gates Micro-V and in a great shape. the harmonic balancer is not wobbly and none of the pulleys look misaligned.

the only thing that caught my sight is the water pump pulley is partially smooth and polished and in small part rusty. now, i remember it being more rusty 6 months before with the old belt. i have no idea if it maters. i'll take a picture if i can.

i noticed coolant a bit on a low side, i hope it's not headgasket from the overheating episode.

Thanks everyone!

a weaping water pump due to an over tight belt trashing the bearings in the pump is a possibility...

and the water pump pulley should be 100% polished looking..unless the car has been sitting a while..the belt should keep it polished

[jack black]

and the water pump pulley should be 100% polished looking..unless the car has been sitting a while..the belt should keep it polished

when the kid was in a school overseas, the car sat for a couple of years with only occasional use (but battery was kept charged religiously). But that changed when she came back in 2021 and she made about 15,000 miles since.

[sh0rtlife]

when the kid was in a school overseas, the car sat for a couple of years with only occasional use (but battery was kept charged religiously). But that changed when she came back in 2021 and she made about 15,000 miles since.

thats why you have some rust spots on the pully they will go away and are nothing to be concerned about...the "sitting" caused the exposed section of the pully to get a bit of surface rust no big deal

[jack black]

Please see the partially rusted water pump pulley.

The second picture is a mysterious part that i found at the bottom of the engine compartment lying on the plastic engine undercover. looks like some part of a pulley, but it doesn't look Yaris specific. I'm sure mechanic left it there by a mistake. does anyone think this belongs to the yaris?

BTW: Happy New Year everyone!

[WeeYari]

The piece in your hand is off of the a/c compressor. I'd check to see if your a/c pulley is wobbling.

[sh0rtlife]

thats litteraly the nut that holds the AC pulley on..

[WeeYari]

Never have I seen that happen. Hang around here long enough and you get to see and hear it all.
Damn good thing you found that piece. Getting it back on and locked down tight will definitely solve the initial purpose of this thread.

[sh0rtlife]

Never have I seen that happen. Hang around here long enough and you get to see and hear it all.
Damn good thing you found that piece. Getting it back on and locked down tight will definitely solve the initial purpose of this thread.

it begs the question tho....how in the hell did it work loose?!?!?!?!

[remcafee]

lol what the hell? the ac compressor pulley flew off?

[Compeer]

Please see the partially rusted water pump pulley.

The second picture is a mysterious part that i found at the bottom of the engine compartment lying on the plastic engine undercover. looks like some part of a pulley, but it doesn't look Yaris specific. I'm sure mechanic left it there by a mistake. does anyone think this belongs to the yaris?

BTW: Happy New Year everyone!

This is crazy glad you can now repair her. That water pump pulley is always going to eat belts and make noise now its in that condition, time to go find a good one at the wreckers to replace it.

make sure you check the water pump and ac bearings for wobble in case those need replacing too as they were taking a beating while the belt wobbled.

[sh0rtlife]

lol what the hell? the ac compressor pulley flew off?

thats the nut that holds the pully on..so i assume the pulley just "hasnt fallen off yet"

[thetut]

Mine did the same at about 18 monts old. I found it laying on the bottom cover and screwed it back on the compressor. That lasted about 10 minutes. Took it to the dealer and they replaced the compressor under warranty. I wasn't happy as I thought some Loctite would solve the problem without disturbing the line set of the compressor which could create future problems.
They insisted so I let them do it and have had no problems since. I am convinced it was a manufacturing defect in that no Loctite was applied from the parts factory.

[jack black]

this is all very weird indeed. i guess it must have unscrewed itself?
i'll try to fix it all the next time i see her. thank you all for helping!

[jack black]

here is an update. after i screwed it on, she left the town and reported no problems with the belt. she came back 4000 miles later and the part is laying in the bottom of the engine compartment again. when you screw it in back, the threaded thing in the middle of the AC pulley just rotates freely with no resistance. so, the part cannot be attached securely and it will get unscrewed again by itself. I have no clue how it works and what is broken. see the picture of the AC pulley and the threaded thing in the middle.
Thanks!

Edit: I found a related thread here: https://www.yarisworld.com/forums/showthread.php?t=42290

[jack black]

Now I suspect it's the AC that is at fault and locks intermittently, tearing the belt. I'll tell my kid to have the compressor looked at. It's probably $$$$.