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. | 
| - | Refer to Maintenance and Lubrication. | 
| • | 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. |