Stationary Engines Scotland

Petter Handyman Oil Engine No. 23345

Mechanical Repairs

The main mechanical issue was the badly bent crankshaft. The bend was too severe to leave therefore the only option was to have the crankshaft straightened. This was considered a risky procedure as there was no way of knowing whether the shaft would snap or crack under the strain of being straightened. As we were not confident enough to attempt repair ourselves we utilised a local engineering company to undertake the repair. Having discussed the repair procedure with the engineering shop, the crankshaft was set up on a large surface plate to assess the 'damage' and establish the correct point at which to apply heat and pressure. The repair went ahead and a few days later we got a call to collect the crankshaft. When we arrived the crankshaft was already set up on a lathe to demonstrate it was running true. We are quite confident the crankshaft had been successfully repaired, however it is always worth bearing in mind that heating, cooling and force can potentially weaken metal components therefore we will ensure the crankshaft is regularly inspected for any defects prior to running the engine.

The broken air / fuel inlet assembly as shown in 'Detailed Inspection' was the other major issue to overcome. Initially we thought that this damage occured when the engine was dragged out of it's original place of work. However on closer inspection there appears to be saw marks on one half of the valve, almost as if a portion was sawn through and then the rest was literally snapped off. Hopefully as time goes on we will find out further details of the engine's original place of work and perhaps why this damage occured. To repair the valve we considered 'jigging' the assembly with a tightly fitting mandrel and silver soldering the parts together. To guarantee an exact alignment would be very difficult as the assembly was not only snapped but distorted and not parallel. As the carrier had to be absolutely parallel to allow the slide to freely move, and also a very close fit to ensure the engine was controlled correctly we considered the best option was to have a replacement manufacturerd. A new inlet valve assembly was made by a fellow enthusiast who reproduced the part to the original specifications. Using the original valve flange, the remains of the old slide carrier was cut off the flange and the flange machined to accept a new slide carrier section which was machined from a solid piece of brass to the exact dimensions of an original item. The whole assembly was then soldered together resulting in an almost invisible repair. Click on the photo to enlarge.

As described earlier the piston had received a crack in the skirt probably due to careless dismantling. This is a classic case of the con-rod being dropped and striking the edge of the piston skirt resulting in the crack. A previous owner has tried to stem the crack by spotting the end of the crack with a drill. This should in fact have been drilled completely through the skirt to prevent the crack spreading. This will be reviewed further before final assembly to ensure the crack won't become an issue.

These pages will be updated periodically as mechanical repairs are identified and carried out.