Before you get excited and do stupid sh?? remove the valve covers and pull the plugs, rotate the engine as far as you can by hand and watch the valve rocker movement.
Make sure you haven't dropped something in a intake port and it got stuck under a valve holding it open and the valve is hitting a piston.
If you pull the LIM back off and you still have the camera look down each intake port and take a peek at the valves.
You haven't blown it up. This all started when you had a oil leak and redid the LIM gasket, it hasn't run since, or even rotated a full rotation.
I will almost bet you have a bolt, nut, large chunk of crap or even a chunk of gasket stuck in a valve.

 

Engine is torn back down t just the longblockplugs have been pulled ill look again in the morning at the valves any way to tell if one is stuck open. Things to look for?

 

Very little upward movement of valve, valve spring may look compressed all the time, rocker and push rod may be loose at points thu out rotation,

 

You may also want to drop the oil pan and see from the bottom. Generally You may have a vision using USB camera in the cylinder area through the spark plug bores, incl. pistons and valves. From the bottom You'll see the rods and crankshaft. Under the valve covers You'll see the rocker arms movement. By removing LIM You'll see the camshaft and the balancer area. That's pretty much of an option.
And remember, not to touch the bolts for connecting rods, bearings and heads without a reason. They are TTY, one time use only.
Also, when You finally find the object, study the problem area and assess the damage.

 

Agree, pulling the oil pan and valve covers is next. Have someone crawl around and listen for the location of the clunk when the engine stops turning. Pay attention to the valves when the covers are off to see which cylinder it is and on which stroke. If after all that and your usb camera experiment, you still don’t know, you have the option of stripping it one piece at a time to see if the long block is ok. First the intake manifold and then one head at a time. It would be silly to pull the whole engine for one bent or blocked valve, or a nut sitting on top of a cylinder.

George

 

I'm guessing that you dropped something into the intake when working on the LIM and whatever you dropped is either inside the cylinder, or is holding the valve open to the point where the valve hits the piston. So take your little USB camera and figure out which two pistons are near the top of the bore when the clunk happens. That will help narrow it down. Take the rockers off and hold a straight edge across all the valves on a head. Is there one valve that is bent and not returning to the same closed position?

Honestly, if you find that you have turned the engine over with the starter, up against something in the cylinder - then you have most likely damaged the aluminum piston/bent the rod and it will fail sooner or later (probably sooner). At this point I don't think it is a rescue operation (damage is done) - but still most people would want to do the recovery and know the cause. I'm just warning you not to have a lot of false hope about this engine being OK.

 

Valve covers have been off and as far as removing the pan only way i can see to accomplish that is to pull the motor thanks for all of your suggestions

 

Les wrote what I have in mind. Well, maybe I wouldn't be nailing that much, just start with assessing the damage. If You consider it minor, You may want to put the engine back, fill in the oil and cross Your fingers to pass 1k miles on the engine. You could be lucky. But if You aren't then You have to pull the engine out over again, and basically do the double job.

 

I have been here many times before, Marine engines or transmissions filled with salt water with forecasts of disasterous exploding rusty valve springs, etc. Many times after working the issue I got a normal life span out of the engine. I gouged the polished surface of a block drilling and tapping new head bolt threads in a Toyota 4 banger and EVERYONE told me that the engine would have to come out and the block surface or the head would not seal. Liquid aluminum, a razor blade, wet sand paper and polishing compound did the trick for $40 and about 2 hours. That was 105,000 miles ago, with 275,000 miles in total. You would be surprised how long some recoveries can last. Depends on where it is and how hard the starter cranked on it.

George

 

Thus I have a huge respect to Your knowledge and skills. I've heard how the head are polished, but never attempt to. I've seen marine diesel engines valve seats being remanufactured, but even if You give me the right tool I don't think I could handle that.
Some of the tasks may be too difficult to do, as they may require knowledge, experience and a proper (sometimes expensive) tools. From my perspective, I'd rather use my mastery skills of another field to earn for a new engine faster than gain the skills on how to polish heads. As, for example, I am on to rebuilding a 4L60 and I am not sure yet if I am - polish adage here - "I am hitting the sun with a hoe".