No. 21 Engine Noise: Notes

• Engine noise from under hood.

• Improper engine oil level.
• Improper drive belt tension.

Rattle sound noise: 

• Loose parts.

Hiss sound noise: 

• Vacuum leakage.
• Loose spark plug.
• Air leakage from intake-air system.

Rumble or grind noise; 

• Improper drive belt tension.

Rap or roar sound noise: 

• Exhaust system looseness.

Other noise: 

• Camshaft friction gear noise or HLA noise.