1978 BMW R100S Engine - Disassembled

Last week while running a standard oil pressure check before igniting the engine, I noticed the left cylinder intake rocker arm had no oil running out. After many attempts and waiting a day to turn the engine, oil was still not seeping through. Working backwards, I took the top end apart thinking that something was blocking the oil passage hole above the engine stud rod. I was astonished to find a factory punch mark for the oil passage hole, but there was no hole. Basically, the technician at the BMW plant, back in 1977 forgot to drill this oil passage hole. After a few sleepless nights, wondering what else this German tech from 1977 forgot to do on this block, I decided to disassemble the engine and check every single oil passage hole.

The oil passage hole I drilled is in picture number three. I took a 2 mm drill bit and slowly drilled through the aluminum until it met the passage behind it. After further investigation of the engine block, everything looks like where it was supposed to be. This cost me a new chain, few rod bolts, and a lot of time, but its better than loosing sleep.