Broken Crank?

Alright guys.
I heard a small bang and my engine quit. I pulled off the super charger and it was locked up. I sent it to Magnum Powers they rebuilt it and Ported it. I slapped everything togehter and it sounds as if I have compresion on two of the cylinders, here is the kicker. No belts moving and no rockers arms that i can see from the oil filler moving please tell me this is something easy!!!!!!!!
Tim

heres a good way to check if your cranks broken...
first lift the front of the car onto stands. Block rear wheels and put in nuetral. (dont mean to sound patronizing, but hey, some people...jeez) then have a helper keep an eye on the fly wheel/pressure plate through the inspection cover. With a large socket wrench try to rotate the motor using the harmonic balancer pulley. If the front rotates and the flywheel/pressure plate doesnt well then....its new motor time

Check the key on the crank snout - if you sheared that off the timing chain won't move. But it still does not sound good.

Aaron

Pulled off the crank pullies. I can now pull the Harmonic dampner out about 1/4" and it slides back an forth pretty easy.

A little more help please. But I am pretty sure it is new engine or sell the car time.
Tim

It sounds like like you need a new harmonic balancer. Remove the old one, Im sure its broke in two.

No belt or valve movement, have you checked to see if your flywheel/flex plate and torque converter are still attached to the crank? Is the starter turning them?

Possibly the super charger locked up which would create considerable drag on the belt which drives it. This would have the effect of a brake being applied on the front of the motor (I would imagine a very squeeky one) and possibly this could have slowed the crank enough to where the torque converter would sheer it's mounting bolts from the inertia of it being in motion? Just a wild a$$ guess but I don't know if it is likely.
But better to be the torque converter than the crank!

SCPilot said:

Pulled off the crank pullies. I can now pull the Harmonic dampner out about 1/4" and it slides back an forth pretty easy.

A little more help please. But I am pretty sure it is new engine or sell the car time.
Tim

Click to expand...

You need to get the HB off and look at the key. If it is sheared off then that is your problem. As long as the snout did not get damaged you can replace the key, damper and timing set. Hopefully you didn't introduce a valve to a piston.

Can you turn a wrench? Barring a bad crank this is a job that anyone with basic tools and a cool head can do. Just make sure if the key is sheared, you put it back together on the bench to verify you have all the pieces.

Aaron

I actually have my shop manual (89) at work today, so if you need a scan of the related diagrams let me know as early as possible.

Broken crank

Sounds like this is your problem. Same chain of events and HB movement.

Mike

HEY! I know that crank. It came off of my car I was lucky and only had to replace the crank. More than likely it happened between the rod journals 1 and 4. If you can afford it, have the engine taken out, and inspected. If the caps and pistons are okay, just put in another crank. If you dont want to deal with it....then thats all you! Like Mike said, I had exactly the same symptoms.

Al

ouch!!!

Aaron