What would cause the serpentine belt to break ?

My Belt split down the middle and one half wrapped around the fan clutch and the other stayed put?What would cause this?

I'm going to replace it today,will use this diagram along with all the tips from this post:

http://www.tacomaworld.com/forum/2nd-gen-tacomas/9268-serpentine-belt-replacement.html


I will also be checking the three idler pulleys. How do I check to water pump?
Thanks

 

You can check your water pump bearing out, but it is not a precise method. With the engine off and the fan belt removed, you grab your fan blade with both hands and watch for any movement back and forth in the pulley as you move your fan blade back to front. You also need to watch your fan as the bearing in the fan clutch may also have some wear in it's bearing. If this is OK, then you can spin the bearing with your hand and see if spins for a length of time or if it stops right away. You can do the spin test with all your pulleys, some spin longer than others, and if one spins longer than most , it may be worn also. None of this is a precise way to test pulley and bearings, it is just the easiest and the fastest, if you have any question of a pulley, you should check it off the Taco. Removing the pulleys off the water pump, AC compressor and PS pump are not easily removed to be checked, the idler pulley can be removed. Good Luck.

 

X2 ^ How many miles are on the belt? Could just be time to replace it also. Keep us posted.

 

I agree with above. Also things to check are EACH pulley for damage, or objects caught in the grooves. Dirt and small stones can get caught up into a pulley and this can cut, or shift a belt off of position. This can result in a cut or torn belt.

 

Either a pulley or tensioner has siezed up from age/wear or other object, or the belt was just slap wore out and came apart.

 

So I installed the belt!
I'm missing a small hose that comes out of the top water pump.
Is there any cooling system diagrams available?

 

It could be anything......

But like others have said.....check ALL the pulleys. Spin every one of them by hand and make sure they all spin freely without any hesitation or roughness. Also - move them side-to-side and in-and-out for linear slop. Sometimes they'll spin just perfectly, but there is SLOP in the bearings. If they're not tight and spinning freely - you need to change the pulley/bearings.

Or...the belt is just old, got a nick, malfunction in it.....or already had a nick in it from factory.

 

Any funny noises when you engage the A/C?

 

All seems fine.
No new noises!
Will have to keep watch for the next couple of days.
P.S. that diagram was so helpful!!!!!!!!

 

I had mine come off a few weeks back. One side was all tore up but it didn't actually break. A few of the pulleys didn't turn too smooth so I replaced them all along with the tensioner assembly. The tensioner is a real PITA to change. Got it all back together and the belt squealed a bit. Did it more when I turned the blower on. Took it off and checked stuff again and sure enough my alternator was really tough to turn. So I replaced that too. All has been fine for the last 500 miles.

 

Update
It ate another belt.
Dealer will be getting all my cash!
I told them if it is to due the timing belt also.
Will tell of the outcome.

 

Did you check ALL the pulleys?? If you have a bad bearing in one of the pulleys, it will continue to EAT belts until you fix it.

 

^^ Janster is correct I believe. Here are my likely suspects:

1. Belt not put evenly on all the ribs of the alternator, water pump, power steering pump, and A/C clutch pulleys.

2. One of the idler pulleys get stiff under load due to lube being dried out or bad bearing.

3. The alternator pulley's bearings become stiff under electrical load or otherwise under belt tension load.

4. The A/C pulley gets stuff under load. The A/C clutch pulley spins freely except when the A/C compressor itself is engaged then the pulley is coupled to the compressor obviously. What may not be so obvious is the A/C compressor also runs automatically while the defrost mode and bimode (defrost/floor) is selected.

 

In various stages of a bearings life...... as they wear, they don't spin as freely or consistently as they should. If you have one belt on a series of 5 pulleys...and one of those bearings is going bad - it creates a speed difference between the bad bearing/pulley and the belt. This creates slippage & heat buildup. Over time, the belt will wear due to the excessive heat/friction. This will also make the belt surface 'inconsistent' and worn which sacrifices the grip on all the other belts. When there's inconsistent grip on the other pulleys - you aren't getting 100% performance from every accessory that the belt is driving.

*sorry, got carried away. I've worked on machinery for 20 years *

 

If the belt is off now you may was well start checking the pulleys and all the accessories. Don't discount the A/C compressor either. Even in the winter the defroster uses it. And they do fail on these trucks. When they fail they tend to lock up solid so if the clutch engages the belt drags. There is a sensor that kicks the clutch off if it senses it not spinning but I've actually seen smoke come off the belt (on my first second gen) when the compressor failed. Whatever doesn't turn freely will be your problem. But holy hell did changing that tensioner assembly suck. I hope that's not it for your sake.

 

The dealer claims I didn't put the belt on right.This time it took out two hoses.
$355 later they claim every thing is in working order. Not the water pump etc. So we will see 12 months or 12,000 miles should act up by then.