serpentine belt isn't spinning

[Chessiemike]

Hi All,
I have a 98 Taurus that has been sitting for a while and now when I start it, it starts up but the serpentine belt isn't spinning. The belt looks ok and I can rotate the belt by hand. What makes the belt spin?
Thanks in advance
Mike

[tripletdaddy]

+Would you clarify a few things?

+What motor do you have?

+Do you smell hot, burning rubber when the motor is turning?

+I'm really surprised you are able to move the belt at all by hand unless you are using a wrench or the Incredible Hulk's hands, if it is as it should be, which I doubt.

+Do any of the pulleys look misaligned, out of place or missing?
+ You should be able to sight along the front of the pulleys or where the belt rides and they should all line up looking from the front of the car and/or straight down from above.

+The bottom most and largest pulley is the driving pulley attached to the crankshaft.

+Is it and all other pulleys turning when you move the belt?

+I take it that no pulleys are turning except the bottom most when you run the engine?

+I'm thinking if something is broken and it's not the belt, your belt tensioner is broken. It looks like a small pulley, probably grooved, connected to a small grey arm with a round pivot point bolted in the center to the engine, inside which is the spring that pushes the arm and pulley against the belt.

+Another possibility is the water pump bearings failed, but I'd expect the pulley to be tilted for the belt to do nothing and coolant to be leaking. It is the large, flat, smooth pulley in the center with the belt flat, back side riding on it.

+Maybe, but not likely, the lowest pulley on the crankshaft has somehow come loose? I really, really doubt that.

DON'T try to run the engine long or take it for a drive, as with it in this condition, the engine can easily overheat, and you will have a much, much more serious problem!!!

[shorod]

Welcome to the forum!

In addition to tripletdaddy's comments, what happens if you push on or pull on the belt when the engine is NOT running? Does there appear to be a decent amount of tension on the belt?

-Rod

[Chessiemike]

Thanks guys for the info. I took a closer look at it today and saw the the crank shaft wheel/pulley wasn't spinning but the shaft was. Also I can move the belt with my hand. I assume that there are gear teeth on the wheel that must have been striped? Have you ever run across a problem like this?

[shorod]

Typically the crankshaft pulley uses a Woodruff key to index the pulley and keep it spinning (along with the slight press-fit). Sounds like the key broke. Luckily the timing sprocket is evidently still where it belongs since the car runs.

-Rod