MF147 engine locked up

[Kenneth S]

Also with the blow by the pistons, and cylinder walls can look good, but the piston rings can be worn out.

 

[jaotguy]

The valves were not 'loose' - there was a large gap between the tappet and the valve stem, and the valves were held shut by the springs. Why would there now be something in the oil pan when all I have done is taken the head off and put it back again? The engine was running beforehand.

sorry , valve and tappet gap was what I meant .... hydraulic lifters are collapsed ( reason for gap )

lack of oil could have locked up one of the lifters ( stopping you from turning it further ) ... backing up may have locked up another ....

time to pull the covers for the lifters and check out if the lifter bores are scored ....

and as suggested , remove the rocker shaft ( equally across the length or you can bend it ) and then try to turn the engine slowly.