Mercruiser 3.0 rotates manually one direction but not the other

[lunderfullife]

I have a Mercruiser 3.0 that I am checking out before using. I freed the engine since it had sat for several years. It rotates counter clockwise by hand but when I try to rotate it clockwise, it goes to a certain point then stops. What might be making this happen?

 

[Scott Danforth]

welcome aboard

broken connecting rod
mice nest in the cylinder
stuck valves

 

[alldodge]

I have a Mercruiser 3.0 that I am checking out before using. I freed the engine since it had sat for several years. It rotates counter clockwise by hand but when I try to rotate it clockwise, it goes to a certain point then stops. What might be making this happen?

If your not getting a full revolution might be rust on the cylinder walls, or as Scott mentioned

 

[kenny nunez]

It could be a broken piston skirt and the piston is rocking and jamming . The main thing it is a sick engine no matter what you find.

 

[Boisebiker]

Can you turn in over more that a whole revolution counter-clockwise? Maybe pull the starter and make sure the gear is retracting.