[s-cars] sheared crankshaft pulley

[John Cody Forbes]

I've had one shear on me while in motion, and have taken apart an engine 
that had damaged it to where it would have sheared soon. In my experiance 
it's not a disassembly problem, it's an assembly problem. If the crank 
pulley is installed with an impact instead of being torqued with the proper 
tools it is highly likely that it didn't get tightened enough and will 
vibrate and slowly wear away the key on the pulley until it finally shears.

The one that sheared on me while driving was a car that I had recently 
purchased and had a t-belt job performed just before I purchased the car. 
Driving down the highway at 70mph I heard a sound that I can only describe 
as the sound you get rattling a piece of silverware in a wine glass and the 
engine lost all power. After costing to the side of the road it was obvoius 
that all compression had been lost. Spinning the engine with the starter I 
could see the flywheel turning, but the crank pulley did not turn. Upon 
closer inspection I could actually see the bolt for the crank pulley turning 
with the crank whle the pulley stayed stationary. That engine lunched all 
ten valves.

-Cody Forbes

David Giannandrea wrote:
> In the thread about t-belt maintenance Robert Myers said he had seen
> two sheared pulleys. From what I've read (and experienced with the
> shop that ruined the oil pump pulling out the crankshaft seal) the
> crankshaft pulley can be ruined if impact tools are used to remove
> the crankshaft bolt.
>
> Additionally, it seems fragile enough to simply fail during a proper
> removal too. When assembled, the pulley is held so tightly with
> 300ftlbs of torqued compression, that I doubt it can move.
>
> Robert. Give up your stories on how it happened. We need to know.
>
> David G.
>
>
>
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