So you've finalized the deal you've been working on for so long and you've dragged home that project engine that's been sitting out in the elements for the past fifty years. It's old, it's rusty, it's ugly, and its piston is stuck tight. What should you do?

There's one secret to piston removal. You know what it is? Patience. Whatever you do, take your time and don't risk causing damage to irreplacable parts.

This is the story of the removal of one piston from one engine. The techniques used may work for you - or not. If you go this route you'll probably have to come up with special techniques and tools to fit your engine, but you'll get the basic idea.

First on the agenda is to remove all parts that will be damaged when you free the piston. If the piston is stuck there's a good chance that other mechanisms will be stuck as well. An enthusiastic pull on the flywheels can break a stuck rocker arm, sideshaft gear or water pump. Remove everything that is in danger. Also, if there is any rust or junk in the cylinder below the piston, clean it off so it won't bind the piston any more as it travels downward.

Now that all the delicate parts are safely stashed elsewhere, it's time to come up with a plan. Your best bet is to hose down the whole area with Yield, Kroil, Gibbs, or some other penetrant and let it sit for a few days or weeks. It can also be effective to fill the cylinder full of brake fluid, transmission fluid, or some other type of oil that has penetrating properties. Actually, it wouldn't hurt to do this as soon as you get the engine home so it has a chance to soak in before you start work on the engine.

If you're going to go the route of using brute force, don't just start whacking on the piston with a hammer. That's a sure way to poke a hole in the crown. Make up a wooden or metallic disk that is the same size as the bore and place it on top of the piston. When you make the disk, relieve the center area so it only contacts the piston on the outer circumference. That's where the piston is strongest.

A trick that can prove helpful at this point is the use of heat. A garden hose ran from the draincock of your water heater into the water jacket can be helpful. Of course if a little heat is good, more is better. The use of a torch with a rosebud tip can heat things up quickly.

If your piston and rod is BIG, don't bother with a hammer. The inertia of the hammer won't be enough to overcome the inertia of the piston and rod. It's a waste of time. You CAN try to use the interia of the flywheels to knock out the piston, but that will be covered later.

The most surefire way to remove a stubborn piston is with grease. The cylinder is pressurized with a grease gun, pushing the piston out. Also, as the cylinder is pressurized, it stretches in an outward direction, loosening its grip on the piston and allowing minute amounts of grease to creep along the sides of the piston.

You need to block off all holes in the cylinder where grease can escape. The valves should be in place, exhaust ports covered, and access holes covered.

If there is a spark plug hole, an adapter can be made to attach the hose of the grease gun. In the picture shown, the grease gun was attached to the plate that was used to block the access port for the exhaust valve. Note that the plate is tapped so the hose can be threaded in directly. There is no zerk fitting. It's much easier to pump grease through a quarter inch pipe than it is to pump it through the tiny hole of the zerk.

Before pumping the cylinder full of grease, you want to eliminate ALL air space. You might be pressurizing the cylinder to 600 psi or more. When the piston finally comes out, that 600 psi of air is going to expand rapidly, distributing a slick layer of grease on the ceiling, the walls, the floor, the dog, and your pretty face. We've found that it's quick and easy to trowel a bunch of grease into the cylinder first, then put in 4x4's and smaller pieces of wood to take up space. You could trowel the cylinder full of grease without wood, but wood is a bit cheaper.

Once you start pumping grease, you might notice that your gaskets leak. It's a minor setback. On this engine, we had problems getting our exhaust valve access plate to seal. In desperation, we coated the gasket with JB Weld and bolted it together. It held the seal well, and wasn't hard to clean up afterward.

Sometimes you have to pump fast to overcome the leakage around the piston. Pneumatically powered grease guns can't pump as quickly as you can by hand, so we've found them to be of minimal value.

On this project we were able to drive the piston out with grease except for about the last four inches. When the piston uncovered the oil hole, grease was able to leak out around the sleeve. It was time to come up with a new plan.

We decided to use the crankshaft and inertia of the flywheels to beat the piston out. Sometimes you can loosen the rod cap on the piston rod enough so you get some flywheel movement. Then by slamming the flywheels back, you can beat the piston out. The drawback of this setup is that the rod bearing can be damaged.

We opted for a slightly different approach. Our goal was to maximize the inertia of the flywheels and minimize the risk of damage to the rod. To impart the most energy to the rod in a rearward direction, the crankshaft needs to impact the connecting rod squarely. See the diagram.

In order to achieve the proper alignment for knocking the piston out, we aligned the rod and crankshaft and measured the distance between them. For our spacer, we opted for a piece of 3 inch square tubing. We planned to cut it lengthwise, place it around the rod, and weld it back together. After putting the pieces in place, it became evident that we could simply clamp the pieces together.

Within about three impacts of the flywheels, the piston resumed its journey rearward. As the piston moved further back, it was necessary to lenghten the spacer, so we welded on more scraps of metal.

After adding a couple extensions to our spacer, the piston was soon out on the floor.

It was very pleasing to find that, even though the cylinder was half full of water, the piston was in nearly perfect condition and there was only minor damage to the cylinder.

Of course now that the piston was out, there remained the problem of removing the four or five gallons of grease from the cylinder. The solution was to find someone who is VERY fond of petroleum products.