Knocks on Start Up Only Last A Few Seconds

The following conditions may produce engine knocks on initial start-up, but only last a few seconds:
^ Improper oil viscosity.
- Install proper oil viscosity for expected temperatures.
^ Hydraulic lifter bleed down
- Clean, test and replace hydraulic lifter, as necessary.
- When the engine is off, some valves will open. Spring pressure against the lifters will tend to bleed the lifter down. Repair the lifter only if the problem is consistent.
- Engines 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 the crankshaft thrust bearing.
^ Excessive front main bearing clearance; Replace the worn parts.
^ Timing chain tensioner malfunction; Clean, inspect and replace the timing chain tensioner, if required.