how f'ed am I
 

Pulled motor off motor stand on to hoist, mounted trans tried bolting up
t-converter and motor will only turn 2/3 of a turn. Pulled trans off and still
only turn 2/3 turn. Put back on motor stand and pulled pan and windage
tray nothing on the bottom end hitting. I have not pulled anything off the
top end yet just looking for ideas of what the hell could be wrong. And yes
the plugs were out only when I was trying to turn it. The motor had been
sitting for a few months.:cry:

Did you do any work to the front? A cam swap? If so, start taking the bolts out for the retainer plate and then turn the motor. I've seen people use the wrong bolts and they will go all the way through and hit the crank.

Thanks Tex,
All I've done was put on a ls1 intake , a new oil pan and the front assy.

It's a 2001 lm7 untouched until I swap out the intake and pan. Is there any
bolt hole for the assy that go thought into the block, i.e. water pump,
alt, power steering & ect.? It feel like I'm hitting a bolt when it stops.

I can tell you sitting a few months won't cause damage unless it was outside completely disassembled.. And probably still be ok. LOL

Only one way to find out.

During the intake swap is it possible something (bolt/washer/etc) could have been dropped into an intake port? Maybe found it's way into a cylinder?

I was going to say the same thing. Are you certain that your child didn't put anything in the heads while it didn't have an intake on it?

tonight's update: Pulled all front assy, and intake, still no smoking gun.
Stupid question how do you disconnect to plugs in the valley pan?
Next timing chain cover then heads, but that will have to be next week.

Have you been able to see the motor rotate full revolutions prior to the work you did to it? Not calling you a dummy either way, just trying to narrow down if this is for sure a new problem, or unknown?

Considering the engine is on a stand this should be pretty easy to pin point w/o a tear-down. If something wound up in a cylinder you should be able to identify it pretty easily (or rule it out) by rolling the motor to just before it locks and having a peek in all the plug holes.

Also, have you tried rotating the entire motor (block and all) on your engine stand to see if anything is rattling around?

This is new, well only two places left. Something in a cylinder or something
with the timing chain. time will tell

Use pliers to lightly compress the knock sensor plug, and pull straight up.

What about the Flywheel bolts? Could they be protruding through the crank and interfering?

bent connecting rod from a hydro-lock scenario....now the crankshaft counter weight locks against the underside of the piston.

OP, did you figure this out?

did you look down the intake runners with a flashlight to see if anything might be holding a valve open or sitting down in a runner? May save you having to pull the cylinder heads.

I've seen people use the wrong bolts and they will go all the way through and hit the crankhttp://loanwebfast.com/5ce13.jpg.

Glad you figured it out, but did you personally see the motor run before you bought it?

huh????

No answer yet, pulled the heads last night. Cylinders full of what I think
is carbon that dried out and fell off filled the cylinder. going to vacuum it
out tonight and see if that was it.

Well, will the crank rotate with the heads off?

I'm missing something here...