A 1/2 HP Maytag Raised from the Dead
Last April, a friend presented me with a challenging problem - a 1918 1/2 HP upright Maytag with a very stuck piston. The piston resisted all conventional removal methods: heat, hydraulics and, finally, a cable doubled around the wrist pin that succeeded only in removing the wrist pin.
I began by mounting the cylinder on an angle plate on the mill, and used a hole saw to remove much of the interior of the piston. A boring head thinned the piston wall until I could peel out the remains with an ice pick. Fortunately, enough of the piston remained so I could obtain dimensions for future reference.
The cylinder was badly pitted, so I used a larger boring head to oversize the bore to 2.030 inches. The cylinder was further stabilized while machining by screwing a 1/2-inch pipe plug into the spark plug hole, clamping the pipe plug in a vise and clamping the vise to the mill table. Of course there was some tool chatter, and the bore tapered down to 0.005-inch smaller at the head. I don't have access to a blind hole or precision hone, so I used what I had available and began lapping the cylinder bore with successively larger cast iron discs. I used a non-embedding compound with the discs and got the cylinder in much better condition.
From 2-1/8-inch gray iron stock I made the piston and rings. I left extra stock length on the piston head to use as a tailstock live center while cutting the ring grooves. The finished piston was also lap-fit with the same non-embedding compound used on the cylinder.
First, I cut the rings from the same gray iron bar, then cut the grooves in the piston to fit. The rings measured 2.060 inches outside diameter prior to installing them. I cut the diagonal gap, then spread and heat treated them. I then pushed the ring up to the exhaust port to check and adjust the gap.
I made a plug to fit snugly in the cylinder; then, using a ball in the 1/8-inch pipe plug hole in the cylinder as a set screw, I trimmed the cylinder base flange perpendicular to the bore. I finished the top of the piston with a band saw, belt sander and ball end mill.
After I cleaned up the crank pin, it was necessary to bore, tin, babbitt and rebore the connecting rod end.
I repaired the cooling fins with a modeling clay form with a sandwich bag mould release and the restorer's friend, JB Weld. I also replaced the crankshaft main bearings while I had everything apart.
At this point I returned it to my friend for assembly and painting. After painting the correct color as near as we could determine, we proceeded with the assembly of the engine. We rebuilt the carburetor and governor and installed a new deflooder valve. We then mounted it on varnished oak skids along with a matching battery box. After considerable tinkering and adjusting, it fired up and ran beautifully. The little Maytag now starts easily with a turn of the flywheel by thumb and makes quite a show. This is how you bring a "Lazarus" back to life!
Contact engine enthusiast Leon Ridenour at: 4610 Sunflower Road, Knoxville, TN 37909; (865) 584-9759.