Why is the crank case full of water on a bombardier jet ski?

The most common reason a crank case would be full of water is due to improper flushing, leaving the water running when the engine is not running. Other possible causes include improper towing (too high a speed or without a hose pincher) and sinking.

Repairs must be accomplished immediately or permanent engine damage will result. Remove the spark plugs and crank the engine until no more water comes out. Use caution not to overheat the starter. Charge the battery as needed to maintain the ability to crank the engine. Then put the spark plugs back in and attempt to start the engine.

You must get the engine running as soon as possible.

Once you have the engine running, turn on the water to cool the engine and exhaust. Run the engine at idle for about four minutes. (You can skip this step if you can get the jet ski on the water immediately.)

Ideally, get the jet ski on the water as soon as possible and ride it for at least ten minutes. This will get the oil and engine up to full temperature and force out any remaining water.