hello have a question I have a 2000 blazer was driving it one day to work and it started running rough so I got it home and open the hood though it jumped time but when I put a trimming light on it I notice the crankshaft pulley wasn't turn but the motor was running and one have a idea whats going on though maybe the keyway got shared off of bad crankshaft senor

 

The crankshaft pulley was not turning with the engine running???

Were you looking at the harmonic balancer instead of the pulley as it is quite possible for the harmonic balancer to separate and the outer ring just sits there. If this is so, then the balancer will need to be replaced which should improve the rough running a bit.

But if the pulley is not turning which means the belt is not turning either....then I believe you are correct in thinking the woodruff key is gone. Hopefully the crank itself is not damaged and just the key....but still going to have to remove the pulley, balancer, hub in order to find-out.

Good luck.

 

A timing light is an obsolete tool on this engine. Ignition timing is not adjustable and it is controlled completely by the PCM.

The pulley bolts directly to the dampener hub, so if the pulley and belt are not turning while the engine is running, the woodruff key sheared off or the hub broke. The tone ring for the crankshaft position sensor is a totally seperate part inside the timing cover. The dampener and the tone ring use the same woodruff key though.

 

so check to see if the woodruff key is sheared

 

If the pulley and belt are not turning while the engine is running, yes, remove the belt and the vibration dampener and inspect the woodruff key and the keyway in the crank and dampener.

 

if the key is sheared off would it throw the motor out of time and would I have to retime it after putting a new key in

 

If it's totally sheared or missing, the engine probably wouldn't run at all. But no, you would not need to time it because the tone ring only goes on one way. You would need to do the crankshaft position sensor relearn though. That's done with a high end scan tool, the el cheapo $500 jobbies that the auto parts stores have, won't do it.

 

it runs but rough and the pulley not turning but it runs

 

If none of the pulleys, and the belt, are not turning when the engine is running: The outer ring of the dampener is mounted in rubber, and as mentioned, it could slip, BUT, the belt pulley is attached to the inner "hub" part of the dampener. The dampener and pulley turn as a unit. The hub is solid, and it's keyed and bolted to the crankshaft. So, if the pulley isn't turning, pull the dampener, (and pulley) off and check the key.