NO.2 ABNORMAL NOISE FROM WATER HEATER UNIT [WATER HEATER SYSTEM]
id0703d1803300
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2
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Abnormal noise from water heater unit
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DESCRIPTION
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• Combustion noise from water heater unit is loud.
• Noise and vibration is transmitted to cabin during water heater unit operation.
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POSSIBLE CAUSE
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• Intake/exhaust system (air intake hose or water heater silencer) malfunction
• Normal combustion cannot be performed (abnormal combustion)
• Insufficient air bleeding of water heater unit water passage
• Improper installation of water heater unit or fuel pump
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Diagnostic procedure
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STEP |
INSPECTION |
ACTION |
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1
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VERIFY MALFUNCTION SYMPTOM
• Is the abnormal noise pointed out by the customer a fluid flowing noise?
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Yes
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Bleed the air from engine coolant.
If the malfunction is not resolved, go to the next step.
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No
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Go to the next step.
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2
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VERIFY WATER HEATER UNIT INSTALLATION CONDITION
• Verify the installation condition of the water heater unit.
• Are the following found?
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Yes
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Install correctly.
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No
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Go to the next step.
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3
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VERIFY FUEL PUMP INSTALLATION CONDITION
• Verify the installation condition of the fuel pump.
• Are the following found?
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Yes
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Install correctly.
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No
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Go to the next step.
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4
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VERIFY WATER HEATER UNIT EXHAUST SYSTEM INSTALLATION CONDITION
• Verify the installation condition of the water heater unit exhaust system.
• Are the following found?
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Yes
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Install correctly.
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No
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Go to the next step.
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5
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INSPECT WATER HEATER UNIT EXHAUST SYSTEM
• Visually inspect the exhaust pipe and silencer of the water heater unit.
• Are they deformed?
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Yes
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Replace the malfunctioning part.
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No
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Go to the next step.
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6
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INSPECT WATER HEATER UNIT AIR INTAKE SYSTEM PIPE
• Visually inspect the air intake system pipes of the water heater unit.
• Are they deformed?
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Yes
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Replace the malfunctioning part.
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No
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Go to the next step.
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7
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DETERMINE IF MALFUNCTION CAUSE IS WATER HEATER UNIT RELATED
• Perform “FFH Start Heater Utility” on the customer’s vehicle and another vehicle of the same model using the M-MDS.
• Compare with the symptom which occurred on the customer vehicle during the combustion test.
• Does the same symptom occur on the other vehicle?
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Yes
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Troubleshooting completed.
The symptom may be caused by resonance from sound or vibration occurring with other vehicle parts, or circumstances with the vehicle when the malfunction occurred (sound echo in surrounding area).
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No
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Replace the water heater unit.
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