Mercruiser 350 IO locked up

[m290slx]

Ran boat yesterday afternoon, everything was fine came in put on lift flushed strb engine perfect,went to flush port engine and it was locked up, no water in oil, ran perfectly smooth no noises, even the lower units were smooth and quiet any ideas?

 

[flashback]

Maybe hydro lock. Pull all sparkplugs and see if it will turn over.

 

[Bondo]

Ayuh,.... Welcome Aboard,..... Like flashback says, pull the spark plugs, 'n see whether it hydro-locked,....

If so, it might be time to pull the exhaust manifolds to see why,....

 

[tank1949]

if salt used boat, I suspect water rusted through head water chamber or manifold. If rusted through, new motor. Sorry.