Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
21 ENGINE NOISE
DESCRIPTION
Engine noise from under hood
POSSIBLE
CAUSE
Squeal, click or chirp noise
• Improper engine oil level
• Improper drive belt tension
Rattle sound noise
• Loose parts
Hiss sound noise
• Vacuum leaks
• Loose spark plug
• Air leaks from intake air system
Rumble or grind noise
• Improper drive belt tension
Rap or roar sound noise
• Exhaust system loose
Other noise
• Camshaft friction gear noise
• MLA noise
STEP INSPECTION ACTION
1 Is squeal, click or chirp sound present?
Yes Check following:
• Engine oil level.
• Drive belts.
No Go to next step.
2
Is rumble or grind sound present? Yes Check drive belt.
No Go to next step.
3 Is rattle sound present? Yes Check location of rattle for loose parts.
No Go to next step.
4
Is hiss sound present? Yes
Check following:
• Vacuum leaks.
• Spark plug loose.
• Intake air system leaks.
No Go to next step.
5 Is rap or roar sound present?
Yes Check exhaust system for loose parts.
No Go to next step.
6 Is knock sound present? Yes Go to flow chart 12 for “KNOCKING/PINGING".
No If noise comes from engine internal, check for friction gear
or MLA noise.
7 Verify test results. If okay, return to diagnostic index to service any additional symptoms.
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