2.6.7.12 Drive Belt Hum Sound Diagnostic
Diagnostic Tips:
Drive belt should not produce hum sound. If there is an intermittent noise, check the attached parts by changing the load. Make sure
that components run until the maximum load. These conditions may be due to (but are not limited to) over filling the air-conditioning
system, power steering system blocked or steering fluid incorrect, as well as the generator failure.
Fault Definition: Sustained High-Frequency Noise
Step 1
Verify the fault. Does the engine hum appear?
No
To diagnose Tips
Yes
Step 2
Remove the drive belt. Confirm whether the hum sound disappears?
(a)
Remove the drive belt. Refer to
(b)
Run the engine, but no more than 30 s.
Does the hum sound disappear?
No
Yes
Step 3
Check whether all attached drive pulley bearings are normal?
Pulley bearings should not appear stuck, loose and so on.
No
Replace the damaged pulley or bearing.
Yes
Step 4
To diagnostic tips.
2.6.7.13 Drive Belt Off Diagnostics
Diagnostic Tips:
If the drive belt falls off from the pulley repeatedly, the reason may be the pulley misalignment. If the attachment drive belt driving
components cause the load fluctuates, it may cause drive belt fall off from the pulley. Test whether accessories driving parts are
working correctly. If the drive belt's length is not proper, drive belt tensioner will not be able to maintain a suitable drive belt tension.
Fault Definition: Drive belt falls off from the pulley, or incorrectly installed on the pulley.
Step 1
Check the drive belt for damage. If necessary, replace the drive belt.
Next
Step 2
Check whether the pulley is misaligned. Repair the faulty part.
Engine
Engine Mechanical System JL4G18-D
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EC718/EC718RV EC715/EC715RV 10/2009
Summary of Contents for EC715 2009
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