• | Improper oil viscosity. Install recommended oil viscosity for expected temperatures. |
• | Excessive piston to bore clearance. |
• | Excessive piston pin to piston clearance. |
• | Excessive crankshaft end clearance. |
• | Excessive crankshaft bearing clearance. |
Some engine noise may be normal for 1-3 seconds at start-up. Be sure that any noise that is identified is really coming from the engine. (i.e. ABS initialization noise)