So you have a seized outboard you're trying to unstick?
Hmmm... what to do? Common causes: Overheated engine Rust Broken piston ring or rod which may be indicated by a cracked or fried coil can result in a damaged piston as well stuck or frozen lower unit All of which may be remedied It's just that some seizeing problems require more money and time to repair. It's all up to the owner as to what to do once the problem and cause have been determined. Stuck piston rings from rust, rust in the cylinders, or on the crankshaft are common problems with a motor that has sat for any length of time, especially outdoors. Well, you have a few options. One may work, none may work. It's a bit of hit and miss. If the motor is seized from sitting, it can be easy to unseize it. However, if your motor seized from overheating, you may be in more trouble than your motor is worth. but, don't quit without trying first. DO NOT force a screwdriver into the spark plug holes in an attempt to force the stuck piston free. I've seen enough of this damage to last me a lifetime. Maybe when parts were readily available it didn't matter if you needed to replace a piston, but now many of the pistons are gone and the survivng parts are used from motors with other damage. DO use a liberal amount of penetrating oil as a first effort. Pour a large amount into each spark plug hole and put the plugs back in and let it sit idle for a week to a month. Every so often try to turn the prop or flywheel if the prop is a shift model. If turning the flywheel gives you any amount of movement, resaturate the cylinders with penetrating oil. This will help to free up small amounts of rust and allow the pistons to move. If you are not getting any movement of the pistons, more drastic measures may ensue. Typically, I will remove the powerhead assembly and take the recoil, flywheel and magneto assembly off of the engine block. Next, I continue by mixing a solution of a few tablespoons of oxalic acid to water in a large enough bucket to soak the entire powerhead, minus the recoil and magplate. This will further dissolve a lot of rust, if there is any in the powerhead. Be sure to wear gloves and thoroughly rinse the block before touching it with bare hands.oxalic acid can aggitate your skin.If, after a few hours of soaking in oxalid acid solution, you still get no movement of the pistons, you may need to disassemble the block.TD disassembly is outlined and is simply a matter of removing the head and the back of the engine block. By removing the rod ends, you can see if the crankshaft has rusted stuck. This sometimes happens, but is not as common of a problem as is stuck pistons from rust, broken rings, or overheated pistons. By applying pressure to the back of the piston rods and front of the piston,alternating between the two, you may be able to work the piston free.assuming the rings are not damaged or broken and stuck. when applying pressure to the back of the piston rod, I use a small block of wood that fits over both the screw holes of the rod end. Tapping lightly on the block of wood on the piston rod end with a hammer may work the piston loose. DON'T Hit the piston top surface with a hammer directly! DO use a block of wood or screwdriver turned blade side up, so you strike the blade with your hammer and the handle is facing against the piston top. but don't ever hit with all your might. common sense? we;ll you'd be surprised what I've seen. Hit it gently, it should work loose eventually with time and patience and lots of penetrating oil or a combination of penetrating oil use and oxalic acid solution soaking. It's a matter of patience and continued tapping over a period of time to work them loose.If the motor overheated, it may not come loose without internal damage, scraping, scoring, or gouging to the inner surface of the cylinder walls and the pistons themselves. This is not an uncommon cause of seizing and would require new pistons if they are too badly scraped and possibly honing of the cylinder walls if they are scored too badly as well. Obviously, there wasn't any scoring when it was new, but the slightest bit isn't going to cause major running problems when reassembled. Good luck and enjoy your project motor. I will gladly assist in any way I can if you email me Big Lures Little Lures with your questions or concerns. Thanks! Steve Mahlberg Big Llures Little Lures Back to service homepage
