Knocks On Start-Up & Lasts A Few Seconds

^ Improper oil viscosity. Install proper oil viscosity for expected temperatures.

^ Hydraulic lifter bleed down is normal and will tend to bleed lifter down. Attempts to repair should be made only if the problem is consistent.

^ Excessive crankshaft end clearance. Replace crankshaft thrust bearing.

^ Excessive front main bearing clearance. Replace worn parts.