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Hey gang, thought I would get your opinion on this. I have never run into anything like it. I purchased a 2004 GTO LS1 with 55k miles on it from a very reputable seller. I put it up on the stand and flipped it over to swap the pan out to an F body pan. After bolting the new windage tray on I decided to turn the motor over to make sure it had clearance and the motor will only turn maybe 80% each direction and then stop. I pulled the tray and it still will not make a full revolution so I bolted the pan on with a couple bolts and flipped the motor over to pull the valve covers. Before I pulled the covers I tried turning the motor over again and it seems to turn over just fine when it's right side up. I turned it back upside down again and it stops at a certain point each way. What the hell could be doing this? Anyone have any ideas? Is this normal? right side up spins fine.
So you had the motor on a stand and turned it upside down? You got yourself a hydro-lock in one or more of the cylinders. Oil has seeped past the rings into the combustion chamber and it is not compressible. Let's hope you have not cracked a piston. Remove all spark plugs and GENTLY try this again.
So you had the motor on a stand and turned it upside down? You got yourself a hydro-lock in one or more of the cylinders. Oil has seeped past the rings into the combustion chamber and it is not compressible. Let's hope you have not cracked a piston. Remove all spark plugs and GENTLY try this again.
Rick
The plugs have been removed. Definitely not hydro-lock
Damn, I was hoping you had a suggestion Michael. Lol. Looks like I might have to pull the heads and see what could be causing this. Maybe something went down the intake during shipping.
"Maybe something went down the intake during shipping."
If that were the case, seems to me it shouldn't matter whether the motor is inverted or not. Is there a flywheel or flexplate on the block? If so, sometimes a part of that will catch on the hardware that attaches the block to the stand - particular there's a bit of bending of that hardware because of the heavy motor cantilevered the way it is. If it wasn't hydro, it's a head scratcher for me.
Although, long as you keep it in the northern hemisphere, you should be ok.
I've been thinking about this all day. With something in a combustion chamber it will fall or slide to the outside wall do to the angle of the piston so it's kind of out of the way. When inverted anything in there will fall onto the valves then get between valves and piston. I'm going to run a scope down the holes tomorrow.
blow some compressed air in the holes and listen for a rattle.
Something that will bind upside down but not right side up...the small angles i can think of that would happen to are the rods at the wrist pins. Broken skirt that falls onto the bottom of the piston upside down but clears the other way? Timing chain tension broke, binding one way but not the other?
I went ahead and pulled the heads and found plastic bits in most the cylinders. Probably sucked in when the car got hit. The power steering pulley was broke so I'm guessing the air box possibly shattered in the wreck and this **** got sucked in. Number 8 had the most pieces. This probably would have never hurt anything to begin with, but now I have piece of mind knowing nothing is damaged.
Just an outside caution -- while the plastic isn't hard enough to damage cylinders or heads the way metal would, you could bend something if you got enough of it in any one cylinder to become un-compressible. I'd give the seller a heads up until you see what you've got on start up.
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LS1 not turning over completely 
