Un seized the piston and engine turned easily turning the flywheel by hand removed flywheel piston down put it back and removed again later dont know if the piston was down engine now tight to turn

First you must determine why is the starter not engaging the flywheel. Is the starter bendix not coming out? Need to remove the flywheel cover and check. Has the flywheel lost its teeth? Is it broken? Check to see if the engine has seized by trying to manually rotate the engine by turning the crank pulley. Sometimes you can put a pipe wrench on it to make it turn. If not you will need to find what size the bolt head is and use a ratchet to turn the engine.

please before you put any more money into repairs ...get a socket and ratchet on the crankshaft bolt and turn it to the right..if it will not turn the engine is seized...you can verify by removing the starter and turning the crankshaft..if it turns you have a problem with the flywheel..GOD BLESS

first with engine cooled down removed spark plugs then turn engine in direction of running rotation by hand from the crank to see if its mechanical related like eg bearing seized. With the spark plugs removed engine must turn easily by hand if not something is holding

The only thing the serpentine belt does it turn the accessories. AIt has nothing to do with the timing of the engine. However, if an accessory has frozen up, power steering pump, air conditioner, alternator, tensioner pulley, idler pulley, etc. it can sometimes prevent the engine from turning over. You can try removing the serpentin belt and then try turning the engine over by hand. with the plugs out. If it turn over easily with the belt removed than check all the accessories.

if it still does not turn over than the engine may be seized...

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Engine compression. Remove all spark plugs and it will turn more easily.

basicly getting your hands dirty ,remove the manifolds drain the antifreeze and make sure the pistons are half way down or up before removing the timing belt after pinning the crankshaft and painting the timing gears for a professional then use the TDC marks but a weekender who is liable to whack the valves putting the head back on the pistons in the middle of the bore and drill a hole to align with the flywheel ringear and tap and thread it to 10mm ,pointed bolt and lock the engine up end of story ,never mind the bar room lawyers and they know it all after two pints they will guide you wrongly ,lock the engine up properly also the bottom pulley does not have a keyway on modern engines and if undone using starter motor then valves will hit the pistons ,same as tightening the bottom pulley up ,not enough pressure then it will come loose on the motor way 6 months later i promise ,but mainly be prepared to make a mess and get your hands dirty with black under the nails ,even more so with a diesel engine then join the clan and be socially outcast for having dirty hands and looked down upon by all and sundry .

hi this sounds rather bad, are you putting it in 3rd gear to start as this would be easier than 1st, can you turn the engine by hand? as the engine could be seized or worse still the cam belt broken and the pistons are hitting the valves, you need to check these things really before trying to start it as you could cause allot of damage to the engine if you have not already done so by push starting it, you also can try jacking up the front so that both wheels are off the ground, put it in 4th gear and try turning the wheels with your hand only one side, if both wheels turn you should be ok, if it is impossible to turn the wheels, you have a seized engine..hope this helps, get back to me when you have tried these things first..ok

Sounds like engine is out of time and pistons are hitting valves locking engine up especially if it turned over and ran before you took it apart this is most likely cause. Remove timeing cover and verify timing marks are properly lined up on gears, then roll engine by hand, if it does not turn then it is hydro locked(fluid in cylinders with valves closed) or mechically locked(dropped a foriegn object into cylinders or bearings/pistons seized). good luck, if out of time you could have bent valves. Need to remove heads and verify if engine has a miss when you get it running.

you can reach down and turn the crankshaft pully by hand to see. If you have a manual transmission, it's even easier; push it a little, put it in 3rd gear, and pop the clutch, and see if the engine turns that way.