Rear of the crankcase. It is imperative that the bearing shells are not damaged during the cleaning and re-assembly process.
The three caps shown in this shot are for the crankshaft rear oil thrower (centre bottom), the rear camshaft bush (upper left) and the oil gallery pipe rear sealing cap (upper right).
This is the rear oil gallery pipe after the end cap has been removed. The machine screw is held in place with a lock tab washer. When removing this screw it is important that the hollow circular plug is not allowed to rotate. Carelessness in this operation will distort the pipe attached to the other side of the plug and could well break the soldered joint.
The screw was removed to allow access for cleaning along the length of the pipe. When the main bearings were line bored the operative failed to blank off the outlet drilling, which meant that a small amount of swarf had entered the oil gallery. Annoying as this was, there was a benefit derived from cleaning the pipe; this rear plug had been twisted at some stage in its history and the cross-drilling was only one third aligned with the outlet tube. Oil supply to the rear main bearing had evidently been severely restricted.