Decided to open up the business end of my Craftsman compressor this morning to see if my problem with compression psi would be easy to diagnose and repair. Thankfully, the problem was immediately obvious. The single piston ring had deteriorated and split at two locations around its circumference allowing air to escape. The cylinder was also scored quite a bit around the top where I believe the piston was contacting after the ring failed.
I pulled the parts manual and ordered a rod kit from searspartsdirect.com but it will probably take a week to arrive and I will be in Oshkosh by the estimated delivery date. Wish there was a parts supply house locally.
Anyway, the rod repair kit includes a new cylinder, rod with piston and ring, and the appropriate gaskets/seals. Should be good to go once the parts arrive. By the way, I was a little surprised at how simple the compressor mechanism is. The cylinder is really just a sleeve and the piston is essentially an allow plate about 1/4" thick with a single ring attached. You can see the upper end of the rod where the piston/ring is mounted in picture 1 below. Not the most robust design I have seen in compressors. I think my next compressor purchase might be a bit heavier duty. Guess I shouldn't complain, the oilless compressor has lasted me a number of years and has seen some serious use during the aiplane build.
