04 C70 Shredded serpentine belt, crankshaft spins freely

[cuhfs]

Just completed 2004 C70 Turbo Timing Belt Change and serpentine belt changed. Used a Goodyear Gaterback Belt.... "Big mistake". After 20 miles the Serpentine belt shredded and wound around the crankshaft pulley. There was a gravel and rock like noise in the front and the car died. Just now pulled and unwound the shreds out from that area and the crankshaft spins freely without having to fight the resistance as would be normal. I should note that the timing marks appear to still be alligned correctly. Maybe one tooth "off" if that. The timing belt is fine. So I guess there is no compression? Any ideas what is most likely damaged? Does this mean a new engine is needed? If valves were bent I assume the crankshaft would not spin? Next step?

[oragex]

Try removing all spark plugs then gently turn the crankshaft by hand. You should be able to feel if the valves are hitting the pistons. This won't tell if some valves are bent just a little. Generally speaking I'm yet to read about one of these engines that didn't bent the valves, sadly.

[BEJinFbk]

Isn't there a shaft key on the crank pulley of a white block?
You may have just sheared it when the serp belt bound it up.
Pull the crank bolt and have a look - Maybe you'll get lucky!

[cuhfs]

I guess if the Shaft key sheared... the engine would still need to be pulled out and apart? Meaning I am still in a bad place...

[abscate]

If I understand correctly the timing belt is fine, just the serpentine belt broke.

Pull the plugs and measure compression. Guessing about major engine damage doesn't really help.

I think if the timing belt didn't move, your top end is ok

[ThommyKent]

Don`t blame the belt, blame the installer. Anyway you sheared the pulley off the end of the crank. You will probably need a new pulley and shaft key the, end of the crank should be ok. If you think you are off one tooth on the timing belt that needs correcting.

[precopster]

There is no shaft key. Just splines:

When engine is timed the dowel you see should be at 12 o clock.

[Ozark Lee]

This story seems like a freak thing but it you are not the first. I can think of three or four others that had the same thing happen to them. When you think of the serpentine belt failing it falls into the "so what" category. Your battery will run down and the car is a pig to drive without power steering but there shouldn't be any other problems other than replacing the serpentine belt.

There are those few times though where the serpentine manages to make its way back behind the timing belt cover at the crankshaft and gets caught up in the timing belt. Then you have problems.

I have used other than OEM serpentine belts like the Goodyear belt and Dayco belts for years with no problems at all. I have even used both of those brands for timing belts but those are usually "Stay Alive" belts that I install when I first buy the car and really don't have a timing belt change history on it. Even then I don't lose any sleep over those brands if they are the correct belt for the car. I think your '04 should have a double sided serpentine belt with ribs on both sides. I wonder if they tried to put on a belt that was wrong for the car?

Have you removed the timing belt cover to inspect what is going on behind it?

...Lee

[rspi]

Strange... if you turn the crank, do the cams move? I don't really understand what you are saying is going on.

If the timing belt is still on and fine, is the harmonic balancer damaged?

[Ben850]

Moderators?
What am I paying for here?
Just kidding.
'04 C70 would be a different forum. Wish I could help.

Just adding, The Idler pulley for the Serp. belt usually needs to be carefully held in place while torqueing bolts.
I am not speaking to an '04, but when the other work was done, that may have been overlooked.