Ever had this happen? Belt Woes

[demon]

Heidi Annes been running good lately with her new rebuild and new timing belt. The other day I started her up (it was 60 degrees outside), drove 300 yrds, pulled out onto the main road and stomped on it. The belt let out a huge SCREEEEETCH! Smoke started rolling out from under the hood. She smoked the belt. Not the bottom, but the top was smoldering and completely disinegrated down a layer to the vetical ply ribs . The bottom looked fine. I babied her home 30 miles not taking her over 2k rpm.

Did I have the belt too tight, and it was cold and needed to warmup and "stretch" first?

I did the finger tension test as prescribed in the bentley and could turn it probably 75 degrees. 90 degrees seemed too loose. Idler pulley is in great shape, and the tensioner pulley is brand new. I have a few thousand miles on her with this setup.

Thanks fellow diesel brains!

[82vdub]

This is the timing belt, right?

Two thoughts come to mind. One, either of the two timing belt covers moved and started rubbing the top of the belt, or, two, something quit rotating that's related to the belt. If the crank quit rotating, the engine wouldn't run. If the cam quit rotating, the engine wouldn't run. If the IP quit rotating, the engine wouldn't run (and those three would sheer the teeth off the belt). If the intermediate shaft quit rotating, you wouldn't have any oil pressure. This leads me to the only one other item that could cause this - the tensioner.

I'd say you were lucky you didn't toss the timing belt and ruin your valves by driving it home.

[TylerDurden]

Given the information that the TB tensioner is new, I'd check the intermediate shaft and vacuum pump very closely.

Check both pulleys for scorch marks and perhaps pull the TB covers to inspect for debris or loose parts that may have fallen into the path.

[the man 53]

another thought is something was on the timing belt cover or you weren't running a TB cover and when you ripped on it things moved around a bit more than normal and something pushed up against it. Then when it was stopped and started that piece flew out. Just guess

[Quantum-man]

I'd go for the scorch marks on the tensioner or halfshaft idea.
If the burn is right across the belt then it is one of the above, if in one area only then something dropped into the path of the belt and wedged.

If a pulley, then check both for stiffness.
If the tensioner is free to spin but has a little play, then at it's resonance frequency it could become hard to turn.

I believe a lot more recent replacement tensioners, are poorly made/lubricated, and may commit the installer to an annual service replacement.

I try to keep the original everlasting tensioners