Jaysteed

So I was driving down the road and I heard sounds like my water pump was going out and then my timing belt snapped. So I replace the water pump and I’m about to put the new belts on and I noticed the rear balance drive pulley isn’t freely spinning. So to further investigate I removed the pulley and it spins freely it just when bolted back to the engine it will not rotate. So I guess I’m just looking to be pointed in the right direction from here