Parts & Accessories Spare parts 454 GMC engine 85. The engine was running and its condition was good and excellent. Suddenly a sound came from it and the engineer said it was moving bearings. We opened it and its condition is this, and I don't know about anything else. I am absolving myself, but the engine's pistons are excellent. If it was opened, it was running and its condition was sound. The reason for the knock is the oil pump, meaning changing the shaft.