I just bought a new slightly used and alot abused 98 Chevy 2500HD. The truck was not running I/P was of and injectors where out of it. Previous owner said it ran but blew alot of black smoke. I put the I\P back on and injectors back in. While put the pump on the th engine turned over fine but I noticed the frount Pulley was bad. Checked the oil purged the fuel system and began the test fire. Cranked Cranked and Cranked somemore stoped to let the starter cool. Started cranking-Locked up and I mean LOCKED UP! Didn't make any strange sound or anything. I don't think it stuck a piston in a hole or spun a bearing. I was wondering what the chance of the crank breaking due to the bad pulley was or if it could be something else.

 

If by front pulley you are refering to the harmonic balancer, then you would be correct in thinking the crank broke. I have seen about 30 or so where the crank broke, and ALL have had a bad balancer.

 

It's the rubber mounted pulley bolted to the frount of the harmonic balancer. I don't know if it could make enough shock to break a crank. Don't know how people drive with them bad I can't stand it.

 

it itself doesn't brake the crank actually, when the pulley breaks it throws the engine out of balance, which then causes the crank to break. It was a design flaw of gm, no way around it. plus those cranks are super weak, which leaves little room for fun on those engine. I am currently building a motor for my truck and i just spent $1800 for a custom forged crank, but i am aiming to beat the horsepower and torque of the worlds fastest 6.5

 

those cranks are really weak. good time to pull the oil pan and check.

so what are your fueling plans?