How to analyze marine engine crankshaft deflection?

I have a 1989 mercruiser 305 v8 marine engine with rusted cylinders and water in the engine.?

• The engine won't crank over. We took you the plugs and water came out and the plugs were rusted. Is there any hope for this engine. We have no money to replace the engine. Also, the boat is a 1996 Chaparral sst in great condition and hate to see it sitting.

• Answer:

  If you can do the work yourself you can try this. Remove the heads off of the engine. Turn it over until the cylinders are at the bottom of the travel run a cylinder hone with oil enough to clean out the rust. If the cylinder walls are pitted I would not invest a dime in it. By the time you finish boring it out and oversizing the pistons, or buying a new power head, you could buy an engine that you know will run and is already in good shape. Even if you bought a new power head, you would still have to check the lower unit. Did you pull the plug on the lower unit? It should be full of gear oil. If water comes out of this, the lower seal where the prop shaft comes out has probably been damaged or compromised. If the gear oil is foamy looking, The oil is probably emulsified with the water. Either way you need a new seal. If the engine will not move because it is frozen up, You can squirt Kroil(or some penetrating oil) into the spark plug holes (fill the cylinders but leave room to put the plugs in), put the plugs in to keep any water from getting in, and let it sit for a week. Remove the spark plugs after a week and try to turn the engine. If you get movement, work it back and forth until you can turn it completely. Then force all of the kroil out with the pistons before putting the plugs back in. You can try to start it at this point, but if the cylinder walls are pitted, it won't run very long before it breaks a piston ring. Then you will have a boat anchor instead of an engine. Make sure you hook water up to the cooling system before running the engine or you will burn it up or damage the water pump. They make "ear muffs" for this and most marine stores sell them.