No. 21 Engine Noise: Notes

21	ENGINE NOISE
DESCRIPTION	Engine noise from under hood.
POSSIBLE CAUSE	Squeal, click or chirp noise: Improper engine oil level Loose installation of solenoid valves Improper drive belt tension Generator installation Auto tensioner bearing malfunction Splash shield or under cover loose (water splashes on drive belt) Rumble or grinding sound noise: Improper drive belt tension Loose parts Hiss sound noise: Vacuum leakage Loose spark plug Air leakage from the intake-air system Rattle noise: Loose parts Rap or roar noise: Dynamic damper loose Exhaust system loose Intake-air system loose Other noise: Electric variable valve timing actuator malfunction Hydraulic variable valve timing actuator malfunction Timing chain noise Hydraulic lash adjuster (HLA) noise WARNING: The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services: Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injury or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this article. (Refer to BEFORE SERVICE PRECAUTION .) (Refer to AFTER SERVICE PRECAUTION .) CAUTION: Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to the fuel pipe and quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign matter.