#
NO.21 ENGINE NOISE

BHE010300103W23

21 | ENGINE NOISE
--- | ---
DESCRIPTION | Engine noise from under the hood
POSSIBLE CAUSE | Squeal, click or chirp noise: • Improper engine oil level • Improper drive belt tension Rattle sound noise: • Loose parts Hissing noise: • Vacuum leakage • Loose spark plug • Air leakage from intake-air system • Improper variable fresh air duct (VFAD) control system operation (13B-MSP (High Power)) Rumble or grind noise: • Improper drive belt tension Rap or roar noise: • Exhaust system looseness Other noise: • Oil pump drive gear noise • Oil pump drive chain noise

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
--- | --- | --- | ---
1 | Is squeal, click or chirp sound present? | Yes | Inspect the engine oil level or drive belts.
No | Go to the next step.
2 | Is rumble or grinding noise present? | Yes | Inspect the drive belts.
No | Go to the next step.
3 | Is rattle noise present? | Yes | Inspect the location of rattle for loose parts.
No | Go to the next step.
4 | Is hissing noise present? | Yes | Inspect for the following: • Vacuum leakage • Spark plug looseness • Intake-air system leakage • Variable fresh air duct (VFAD) control system operation (13B-MSP (High Power)) (See Variable Fresh Air Duct (VFAD) Control System Operation Inspection (13B-MSP (High Power)).)
No | Go to the next step.
5 | Is rap or roar noise present? | Yes | Inspect the exhaust system for loose parts.
No | Go to the next step.
6 | Is knocking noise present? | Yes | Go to the symptom troubleshooting "No.13 Knocking/pinging/detonation-Acceleration/cruise". (See NO.13 KNOCKING/PINGING/DETONATION-ACCELERATION/CRUISE.)
No | If the noise comes from engine internally, inspect for oil pump drive gear or chain noise.
7 | Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. • If the malfunction remains, inspect the related Service Information and perform the repair or diagnosis.