Archived 2005 Broken idler bolt & serp belt AGAIN !

[adnach]

About 5k mi ago bearing went in idler and wiped out tensioner & belt.
I installed new idler, tensioner, & belt.
Had been behaving fine until today, snapped off idler bolt, bent tensioner, & shredded belt. Sent idler pully into a.c. and broke a line lost the a.c. charge.
Towed it home. Checked alt, p/s, water pump, fan, a.c. all seem to rotate nice and smooth. Idler & bearing look fine.*
Something had to lock up to snap off idler bolt in the block and bend the tensioner..this truck has 148k on it.
It is the 4th belt. Had a belt go around 75k then a tensioner at 100k.
What am i missing?
Thanks in advance,
adnach

 

[Missouri Mule]

When or did you get the ac line fixed, turn on a/c and see if pulley moves. Clutch on a/c pulley mite be acting up.

 

[Bob4x4]

Were they oem parts or aftermarket?

 

[petersonj]

Something had to lock up to snap off idler bolt in the block and bend the tensioner..

If the tensioner bolt is properly torqued and the tensioner mating surface is clean and smooth and the tensioner index pin is seated properly, I don't think it would be possible to break the mounting bolt, even with other component failures. I think it is more likely that the bolt was under-torqued or grossly over-torqued, or something interfered with the mating surface, or the index pin was not quite where it should have been. Any of these scenarios could cause the bolt to become loose and then eventually shear suddenly. The rest of the damage could be a result of parts flying around.

I could be wrong about this, but it is something to consider. If you can, inspect the mounting bolt. If the break is clean and neither part of the bolt is bent or beat up, then something probably did shear the bolt in one clean sweep, But, if either part of the bolt is bent or shows wear or scuffing from repeated forces, then I would suspect that one of the above-mentioned scenarios occurred.

- John

 

[adnach]

Were they oem parts or aftermarket?

Gates tensioner, cummins idler, green stripe belt from Geno's garage...

 

[adnach]

John, idler bolt broke off. Tensioner is ok and tight but looks tweaked from being yanked on.
Good point though i will look at it carefully whe i take it off. Would think of i didnt get it indexed right it would have misbehaved sooner

 

[jhenderson]

I've never seen a locked up accessory break any hard parts. It usually simply overheats and destroys the belt if you don't notice the God awful noise and vibration first.

 

[cerberusiam]

Tensioner bolt backed out, idler bolt backed out, idler bearing seized, could be any of them. The wrapping of the belt when it came loose on the either the tensioner or the idler will cause further parts failure. Hard to tell what was the real source of the failure and what was collateral damage. replace idler bearing, idler bolt, tensioner and bolt. They are all suspect now.