Knocks on Initial Start-Up But Only Lasts A Few Seconds

- Improper oil viscosity. Install proper oil viscosity for expected temperatures.
- Hydraulic lifter bleed down. Clean, test and replace as necessary.
- When the engine is stopped, some valves will be open. Spring pressure against lifters will tend to bleed lifter down. Attempts to repair should be made only if the problem is consistent.
- An engine that is operated for only short periods between start-ups may have lifter noise that lasts for a few minutes. This is a normal condition.
- Excessive crankshaft end clearance. Replace crankshaft thrust bearing.
- Excessive front main bearing clearance. Replace worn parts.