bigwheel

Old thread but I though some might be interested. When installing the cotter pins the hoop end of the pin must be seated inside the nut castellations. This usually requires mashing the head of the pin to make it seat deeper in the castellations. If this is not done the hoop of the pin will catch on the bottom edge of the cylinder bore and eventually will break the pin in precisely the same manner shown in the OPs pictures. Also, if your unlucky you’ll have the old perforated tube suction screen, rather than the updated mesh suction screen like the OP has. The perforated tube screen will allow the chucks of cotter pin to pass through it and reach your oil pump. Your oil pump will then chop up the pin into smaller chunks while destroying itself and the oil pump cavity built into the accessory cover. In my case the bottom cotter pin on all six cylinders was either broken, missing, or damaged. None of the nuts had loosened, as should be the case of a property torqued fastener.