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Home >> Chevrolet >> 2017 >> Malibu LS >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Mechanical - 1.8L (LKN)) >> Diagnostic Information and Procedures >> Drive Belt Rumbling and Vibration Diagnosis >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2 

    This test is to verify that the symptom is present during diagnosing. Other vehicle components may cause a similar symptom.

  2. 3 

    This test is to verify that one of the water pump belt causing the rumbling noise or vibration. Rumbling noise may be confused with an internal engine noise due to the similarity in the description. When removing the water pump belt the water pump may not be operating and the engine may overheat. Also DTCs may set when the engine is operating with the water pump belt removed.

  3. 4 

    Inspecting the water pump is to ensure that they are not causing the noise. Small cracks across the ribs of the water pump belt will not cause the noise. Belt separation is identified by the plys of the belt separating and may be seen at the edge of the belt or felt as a lump in the belt.

  4. 5 

    Small amounts of pilling is normal condition and acceptable. When the pilling is severe the water pump belt does not have a smooth surface for proper operation.

  5. 9 

    Inspecting of the fasteners can eliminate the possibility that the wrong bolt, nut, spacer or washer was installed.

  6. 11 

    This step should only be performed if the water pump is driven by the water pump belt. Inspect the water pump shaft for being bent. Also inspect the water pump bearings for smooth operation and excessive play. Compare the water pump with a known good water pump.

  7. 12 

    Accessory drive component brackets that are bent, cracked or loose may put extra strain on that accessory component causing it to vibrate.

Step Action Yes No
CAUTION: Refer to Belt Dressing Caution .
DEFINITION: The following items are indications of water pump belt rumbling:
  • A low pitch tapping, knocking or thumping noise heard at or just above idle.
  • Heard once per revolution of the water pump belt or a pulley.
  • Rumbling may be caused from:
    • Pilling, the accumulation of rubber dust that forms small balls (pills) or strings in the water pump belt pulley groove
    • The separation of the water pump belt
    • A damaged waster pump belt
DEFINITION: The following items are indications of water pump belt vibration:
  • The vibration is engine-speed related.
  • The vibration may be sensitive to accessory load.
1 Did you review the Water Pump Belt Symptom operation and perform the necessary inspections? Go to Step 2  Go to Symptoms - Engine Mechanical 
2  Verify that there is a rumbling noise or that the vibration is engine related.
Does the engine make the rumbling noise or vibration?		 Go to Step 3  Go to Diagnostic Aids 
3 
  1. Water Pump Belt - Remove - Water Pump Belt Replacement 
  2. Operate the engine for no longer than 30-40 seconds.
  3. Repeat this test if necessary by removing the remaining belt(s).
Does the rumbling or vibration still exist?		 Go to Symptoms - Engine Mechanical  Go to Step 4 
4  Inspect the water pump belt for wear, damage, separation, sections of missing ribs and debris build-up.
Did you find any of these conditions?		 Go to Step 7  Go to Step 5 
5  Inspect for severe pilling of more than 1/3 of the pulley grooves.
Did you find severe pilling?		 Go to Step 6  Go to Step 7 
6
  1. Clean the drive belt pulleys using a suitable wire brush.
  2. Reinstall the water pump belt. Refer to Water Pump Belt Replacement .
Did you correct the condition?		 Go to Step 8  Go to Step 7 
7 Water Pump Belt - Install NEW - Water Pump Belt Replacement .
Did you complete the replacement?		 Go to Step 8  Go to Step 9 
8 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 9 
9  Inspect for improper, loose or missing fasteners.
Did you find any of these conditions?		 Go to Step 10  Go to Step 11 
10
  1. Tighten any loose fasteners. Refer to Fastener Specifications .
    CAUTION: Refer to Fastener Caution .
  2. Replace improper or missing fasteners.
Did you complete the repair?		 Go to Step 13  Go to Step 11 
11  Inspect for a bent water pump shaft. Refer to Water Pump Belt Replacement .
Did you find and correct the condition?		 Go to Step 13  Go to Step 12 
12  Inspect for bent or cracked brackets.
Did you find and correct the condition?		 Go to Step 13  Go to Diagnostic Aids 
13 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 3 
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