A 'Lazarus' Project

A 1/2 HP Maytag Raised from the Dead


| October 2005



1_2HPMaytag.jpg

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.

Extreme Extraction

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.