2.13.7.12 Drive Belt Hum Sound Diagnostics 

Diagnostic Hints: Drive belt should not produce hum sound. If there is an intermittent noise, 
inspect 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, blocked power steering system or incorrect steering fluid, as well as the 
generator failure. 

Fault Definition: Sustained High-Frequency Noise 

 

2 

Dismantle the drive belt, confirm whether the hum sound disappears? 

A.  Dismantle the drive belt. Refer to 2.13.8.3 Replacement of Drive Belt. 

B.  Run the engine, but no more than 30 s. 

Does the hum sound disappear? 

 

3 

Inspect whether the bearings of all accessory drive belt pulleys are normal? 

Pulley bearings do not appear stuck, loose and so on.

 

 

4 

To Diagnostic Hints 

1 

Verify the fault. Does the engine hum appear? 

No 

Replace the damaged pulley or bearing. 

Yes 

No 

Refer to 2.13.7.4 Engine Noise Diagnosis 

Yes 

No 

To Diagnostic Hints 

Yes 

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2.13.7.13 Drive Belt Falling-off Diagnosis 

Diagnostic tip: the drive belt dropped from the drive belt pulley repeatedly may ne caused by 
dislocation of the belt pulley. 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 
components 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 are incorrectly installed on the 
pulley. 

 

2 

Inspect whether the pulley is misaligned. Repair the faulty part. 

 

3 

Inspect whether the pulley is bent or depressed. Repair the faulty part. 

 

4 

Inspect whether the drive belt tensioner device bracket is bent or cracked. Repair the 
faulty part. 

 

5 

Inspect whether the drive belt tensioner device is working properly. Repair the faulty 
part. 

 

6 

Inspect whether the drive belt tensioner device is working properly. Repair the faulty 
part. 

 

7 

Inspect whether the attached fasteners loose. Repair the faulty components. 

 

8 

Confirm that the fault has been fixed. 

1 

Inspect the drive belt for damage. If necessary, replace the drive belt. 

Next 

Next 

Next 

Next 

Next 

Next 

Next 

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2 . 13 . 7 . 14 Overwork of drive belt 

Diagnostic tip: the excessive wear of the drive belt is usually caused by improper installation or 
the user of the wrong belt. Drive pulley slight misalignment will not cause excessive wear and tear, 
but it could lead to drive belt noise or loss. Drive pulley misalignment can cause excessive wear 
and can also lead to drive belt fall off. 

Fault Definition: The drive belt is not properly installed which led to the drive belt outer 
edges worn. 

 

2 

Inspect all attachments drive belt pulley for whether there are abnormal scratches on 
the surface, edges and corners and other abnormal conditions? 

 

3 

Inspect whether the installed drive belt model is correct? 

 

4 

To Diagnostic Hints 

 

1 

Inspect whether there are frictions between drive belt and brackets, harness, hoses and 
other components? 

Yes 

Replace the drive belt with a correct type. 

No 

Yes 

Repair the faulty part. If necessary, replace 
the belt pulley 

No 

Yes 

Repair the faulty part. 

No 

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2.13.8 Removal and installation 

2.13.8.1 Engine hood cover replacement 

Dismantlement Procedure 

1. 

Dismantle engine plastic 
protective cover fixing nut. 

NL02-0078b

2.  Remove the plastic shield of 

engine. 

 

Installation Procedure: 

1.  Install engine cover onto engine 

cover positioning bolt. 

2.  Tighten engine cover nut. 

Torque :7N . m(Metric) 5 . 
2lb-ft(English system) 

NL02-0079b

 

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