Excessive main journal wear?
I just recently rebuilt a 232 6 cylinder engine out of a 73 Javelin. I changed the oil and filter every 4000 miles and never ran the engine hard. The engine had about 125,000 miles on it when I took it out of the car. I used standard 10w40 oil.
When I took the engine apart everything looked good except the crankshaft. The front and rear journals and bearings looked real good but the main journals and bearings toward the center of the crankshaft were worn so bad the crankshaft had to be replaced. The rod bearings and cam bearings looked good.
Does anyone have an explanation as to why the main journals and bearings toward the center of the crankshaft were the only area of major wear in the whole engine?
Do you think switching to synthetic oil and a higher quality filter would prevent this from happening in the future?