NO.21 ENGINE NOISE [L8, LF]

id0103a0802700

21 | ENGINE NOISE
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DESCRIPTION | • Engine noise from under bonnet.
POSSIBLE CAUSE | Squeal, click or chirp noise: • Improper engine oil level • Improper drive belt tension • Generation installation (alignment) • Splash shield or under cover looseness (splashed water to drive belts) Rumble or grind noise: • Improper drive belt tension • Improper P/S fluid level Rattle sound noise: • Loose parts Hiss sound noise: • Air leakage from intake-air system • Loose spark plug • Vacuum leakage Rap or roar sound noise: • Dynamic dumper looseness • Exhaust system looseness • Intake-air system looseness Other noise: • Camshaft friction gear noise or MLA noise • Timing chain noise • PCM malfunction

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Is a squealing, click or chirping sound present? | Yes | Inspect the following: • Engine oil level • Drive belt tension • Generator installation (alignment) • Splash shield or under cover looseness Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
2 | Is a rumbling or grinding sound present? | Yes | Inspect the drive belts or P/S fluid level. (See DRIVE BELT INSPECTION [L8, LF].) Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
3 | Is a rattling sound present? | Yes | Inspect the rattling location for loose parts. Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
4 | Is a hissing sound present? | Yes | Inspect the following: • Intake-air system leakage • Spark plug looseness • Vacuum leakage Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
5 | Is a rapping or roaring sound present? | Yes | Inspect the looseness for the following: • Dynamic damper • Exhaust system • Intake-air system Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
6 | Is a knocking sound present? | Yes | Go to the symptom troubleshooting "NO.13 KNOCKING/PINGING-ACCELERATION/CRUISE". (See NO.13 KNOCKING/PINGING-ACCELERATION/CRUISE [L8, LF].)
No | If the noise comes from the engine internal, inspect for friction gear, timing chain or MLA noise. Repair or replace the malfunctioning part according to the inspection results.
7 | Verify test results. • If normal, return to diagnostic index to service any additional symptoms. (See ENGINE SYMPTOM TROUBLESHOOTING [L8, LF].) • If malfunction remains, inspect related Service information perform repair or diagnosis. ― If vehicle repaired, troubleshooting completed. ― If vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [L8, LF].)