ForcesR

I have seen and have experienced hydra lock in Saito gas engines during hand starting. On my FG36 I over choked the engine by drawing more fuel into the carburetor by doing 6 flips of the prop, instead of 4 during the first start of the day. From the time it took me to return the choke extension tool to my tool box and turning the ignition switch on, I had hydra lock. I knew it was hydra lock because the prop would not flip through the compression stroke, it bounced back in the opposite direction of prop rotation. I tried a total of 3 flips of the prop by hand, same result, the prop would not pass through the compression stroke. I began to remove the spark plug cap so I could remove the plug and clear the hydra lock. A fellow club member came over to where I was working and asked what I was doing, I said I was removing the spark plug to clear a hydra lock and explained to him what had happened. His response was, you don't have to remove the plug, all you have to do is hold the two prop blades and force the engine through the compression stroke two or more times to clear the fuel from the cylinder. I told him he didn't have a clue how to properly clear a hydra lock, and his method would more than likely cause damage to the engine.

I wonder if the FG60 owners that have experienced cylinder head failure have had hydra lock and didn't recognize it as hydra lock during hand starting when the prop would not pass through the compression stroke two or more times? Then not correctly clearing the hydra lock?