I'll try to make this short while including the crucial details. Bought a built 5.3 that was bored to a 347. Ran when it came out of the car. Swapped oil pan/windage tray/pickup tube with GTO components and bolted everything back up. Everything looked great, no metal or noticeable issues with the pan off. Set the engine in the car and bolted everything up. Using a monster LT1SC clutch and monster flywheel. The transmission is a tick built t-56 bolts to a quicktime bellhousing. Everything is going into an 04 GTO.

The motor sat for a few months. Inside and covered, of course, and had oil in it. Once everything was swapped it was put in the car and mated with the trans. We attempted to turn it over with the starter just to make sure everything was good to go and the starter would engage, but not spin. Wasn't sure if the battery was weak or not. We removed the starter and it would engage and spin. So while waiting for a new battery we removed the plugs and tried to turn the motor over by hand with a breaker bar and cheater bar. It wouldn't budge. It would not spin in either direction whatsoever.

The transmission is coming out tonight or tomorrow to make sure there's not a clearance issue with the flywheel, but I want to make sure I'm not overlooking anything. Any help would be greatly appreciated.

Thanks in advance.

 

If that's all you did was replace windage tray, pickup, and pan, the only thing I could think of is the crank counterbalances getting hung up on the windage tray.

 

We're pulling the trans to make sure there's no interference using a clutch/flywheel for an LS1 on the 5.3, which I really doubt there will be. If that doesn't resolve the issue the pan will come off and we will inspect it from there.

 

The first thing I would do is drain the oil, pull off pan and windage tray then try to turn over before you pull tranny

 

Check the length of the flywheel bolts

 

just curious but how will that cause the motor to sieze?

 

I'm curious as well, mainly because that seems to have been the issue.

Since it's in a GTO and the only way to really pull the pan without dropping the cradle is to pull the engine, we unbolted the trans, clutch and flywheel. It was locked up all the way until the flywheel came out and then it completely freed up. Thank God.

 

when you pulled the tranny out and the flywheel/clutch/pressure plate was still on the motor, was is still siezed?

 

Bolts were too long and hitting the block.

 

the flywheel bolts or pressure plate bolts? I could see how the pressure plate bolts could do that but how with flywheel bolts if they are just tapped into the crank?