We reached a roadblock in the restoration process of my 12-year-old son Steven's 1918 Fairbanks-Morse headless 1-1/2 HP engine. After careful and complete disassembly of the rusted mass (or should I say mess?) of iron, we had been unsuccessful at freeing the stuck piston.
Soaking with Kroil, fuel oil, WD-40 and pounding (gently) on the exposed piston skirt had yielded no sign of movement. With no cylinder head to remove to gain access to the top of the piston on which to pound/press it out, options were few.
We decided to try hydraulic pressure. We fabricated a steel plate to cover the igniter opening. Nothing high-tech here, just a scrap piece of 3/8-inch plate in which two clearance holes were drilled to go over the igniter mounting studs. Halfway between the stud holes we drilled and tapped for the installation of a zerk fitting.
Steven then made a set of new gaskets. We laid the engine on its side, installed the mixer casting and exhaust valve. I then filled the cylinder with fuel oil through the igniter assembly opening to displace all the air in the engine. Steven installed the zerk plate and began pumping the cylinder full of grease with the grease gun.
Unfortunately, we found the new gaskets oozed and fuel oil was leaking past the exhaust valve. We could not build any pressure with all the leaks. We did not have a problem with the intake valve since it was still rusted tightly in the mixer casting. I didn't want to mess with valve seat machining since the cylinder might also need machining. And I did not want the engine possibly going to the shop twice! What to do?
Since heat would not be an issue I decided to make another set of gaskets out of an old inner tube. I also made a rubber washer to install on the exhaust valve. I found a stiff spring to put on the exhaust valve stem to pull the valve tight, thereby pinching the inner tube washer tightly between the valve and seat.
We topped the engine back up with fuel oil, reinstalled the zerk plate and Steven again began pumping the cylinder full of grease. He had just started to build a little pressure and fuel oil squirted out the cylinder oiler hole. Drat! Forgot about that! It took a few days to locate a 1/4-inch NPT pipe tap to chase the threads and remove the remnants of the rusted oiler pipe. Finally, we finished and plugged the oiler hole.
Yet again Steven manned the grease gun and began pumping. Pressure built quickly, and as he commented that it was getting difficult to pump I saw it … piston movement! Excited, he pumped faster, and with each pump stroke the piston moved ever so slightly. The pressurized fuel oil began to ooze its way past the piston. He continued until the gun was empty. The piston had traveled to the point where the wrist pin was nearly clear of the bottom of the cylinder! But, alas, that was my last tube of grease. Rats! We quit for the night, disappointed we had not achieved the goal but excited that we were so close! Later, on the way to his Boy Scout meeting, we stopped and bought a case of cheap grease.
The next day, armed with more grease, I reloaded the gun and Steven set me to pumping, telling me, "You can have the honors, Dad!" As the lower piston ring became fully exposed, fuel oil began squirting past the piston and we could not maintain any pressure to continue movement. Noticing the piston was cocked slightly to the side, I grabbed the skirt with one hand and took a stick in the other and gently pried the piston back and forth and wiggled it out. Success at last!
On a related note: Since Steven got the engine, we had concern the cylinder could be cracked. The engine had been sitting upright in a farm field exposing the open hopper to rainwater, snow, dirt and leaves. Over the course of the many years of exposure to freezing/thawing cycles, it seemed very likely such damage would have taken place. However, the process of hydraulic piston removal produced a side benefit: The cylinder has been pressure tested and shows no sign of leaks!