My Chinese made tractor decided to do a nasty, not only did it develop a knock that would rival King Kong with a sledge hammer it also managed to fire the dip stick 30' into the air
After a brief examination (means removing everything but the block and crankshaft I found the problem
It appears the poor honing of the bores was letting diesel mix with the lubricant in the sump. The rate of the dilutution was about the same as the rate of oil being burnt so the dip stick always showed about the right level. Unfortunately, oil and fuel don't make a good lubricant and #2 big end decided to protest and started doing laps around the cranskshaft ending with about 4mm wear and a rapid drop in oil pressure. Not only did the bearing disintergrate but it also left some pretty nasty grooves in the crank.
The dilema is.... it is a massive job to remove the crank and block because it holds the entire tractor together including front diff and loader frame. Not only that, the tractor (with loader removed) is most likely only worth what it will cost to reco assuming I can get parts from China. This where the "Bush Mechanic" comes in.
I figure I can resurface the #2 crank big end by fitting emery cloth in the conrod and winding the motor over on the starter motor. Then progress to finer grade abrasives until I have a reasonable surface back on the crank. I expect to take 2-3 thou off which then leave the issue of dressing back an undersize bearing and trying to get a reasonable fit to maintain oil pressure. If that works I will then hone the bores, fit new rings and see how long it goes. Surely it can't be worse than the way it was built new, I hope. I intend videoing the machining process, I'm sure it will inspire many a budding mechanic to take baling twine and fence wire to the next level.
Anyway, how do the talented mechanics out there rate my chances of success?
By the way, I don't work on bikes with the same degree of ground breaking engineering technique so you needn't worry about my Scorpa's!!
