Experience....
get a cylinder hone and clean it out spray it down with wd40 to help make a coating and penatrate the rust check the piston rings and get it back together also when you grab the flywheel you may want to remove the sparkplugs from expearance it turns kinda hard with plugs in. Also before you put it way did you spary fogging oil or wd40 in the cylinder before you winterized?
:agree: .... This is a prime example of why it's so necessary that you fog a motor before shutting down for an extended period of time.
This is usually caused from humidity that builds in your engine compartment bay from the changing temps. You can judge the level of humidity in our engine compartments fairly easy. After you set the boat up for a few days, open the engine bay. If you notice small water droplets all over your metal surfaces, like you exhaust, then you have a really high humidity level present. This moisture will likely find it's way into your crankcase via the intake manifold.
The best way to combat moisture in your engine compartment is to leave your plugs out and keep the inner compartment removed and stored in your garage. Then, before putting on your cover, open and place a small wedge in between the cover. This will allow the moisture that is evaporating, to find it's way out. If your engine bay is holding a lot of water and your in an area with high temp and humidity changes, then you might want to remove all excess water with a shop vac before storing.
The idea of using WD-40 to help lubricate the cylinders before turning is a good idea. I would not try to turn the crank without it. The problem you could face is pitting. If a pit has been created and is hard, you attempt to turn the crank, you might damage a ring. You should work this back and forth, gently. Use a hone, some oil or just a super fine grit piece of paper. You only want to knock off the outer rust surface, don not try and shine it clean. Once the engine is running again, it'lll clean it up for you.
The last thing you need to consider is, if you've rusted the cylinders like this, what might your main crank bearings look like? Or, was the rust also contributed to water stored in the crankcase.
Keep us posted, I'll be looking at your progress.:cheers:
