O.S. 15 DIESEL REBUILD

This engine was sent to us by my good friend Trevor Henderson with the statement "you can have it to repair" Ok thanks. Here's the engine as we received it from Trevor. Complete but with broken fins and absolutely no compression, oh and a contra piston with a very sloppy fit.

First step is to dismantle and inspect this classic engine.

Well that's a bit inconvenient, the rear bearing is a bit rough and it's an odd size special that isn't available anymore, anywhere.OH DEAR, NOW WHAT??

O.K. so having left this engine alone for quite some time we have made a decision on how to go ahead with the restoration without having been able to source an original sized bearing. Our initial thought was to go the whole hog and remachine the entire case to allow for a standard sized bearing to be used with the added bonus of increasing the crankshaft diameter to allow better fuel/air intake and therefore more power, however once this option had been properly investigated we realized that there simply isn't enough meat in the sandwitch to allow excessive removal of case material to make that a viable option. So, now what? well we'll make a new crank that we can fit a stand 12x 21 x5 ball bearing onto and step the crankshaft back down to the standard 10.50mm diameter of the original shaft. With the smaller outside diameter of the bearing we will make a simple resizing cup that fits over the new bearing and into the preexisting case hole so no remachining of the original case dimensions is necessary.

YAY, now we have a workable plane let's get things under way.