Pinpoint Tests

Diagnostic Routine A

Diagnostic Overview

Accessory Drive Belt Noise or Flutter

Pinpoint Test

NOTE: Under no circumstances should the accessory drive belt, tensioner or pulleys have any fluids or belt dressing applied to them as damage to the belt material and tensioner damping mechanism may occur.

1. CHECK THE ACCESSORY DRIVE BELT

1. Check the condition of the accessory drive belt and for correct installation. REFER to Accessory Drive Belt .

Is the accessory drive belt acceptable?






2. CHECK FOR FLUID CONTAMINATION ON THE ACCESSORY DRIVE BELT

Is the accessory drive belt clean and dry?






3. CHECK FOR DAMAGED ACCESSORY DRIVE BELT TENSIONER

1. Test the accessory drive belt tensioner. REFER to Accessory Drive Belt Tensioner Testing and Inspection.

Does the accessory drive belt tensioner function correctly?






4. CHECK FOR PULLEY MISALIGNMENT OR EXCESSIVE PULLEY RUNOUT

1. Determine the area where the noise comes from.

2. Check each of the pulleys in that area with a straightedge to the crankshaft pulley.

3. Look for accessory pulleys out of position in the fore/aft direction or at an angle to the straightedge.

Is the pulley(s) misaligned or have excessive pulley runout?






5. CHECK FOR DAMAGED ACCESSORIES

1. Remove the accessory drive belt.

2. Check that each accessory pulley can be rotated by hand in the unloaded condition.

3. Check that each accessory pulley does not feel loose or is binding.

Do each of the accessory pulleys rotate smoothly by hand?






6. CHECK THE A/C SYSTEM PRESSURE

1. Test the A/C refrigerant system. REFER to Refrigerant System Tests Component Tests and General Diagnostics.

Does the A/C system pressure exceed specifications?