Initial Inspection and Diagnostic Overview
Inspection and Verification1. Verify the customer's concern by operating the engine to duplicate the condition.
Visual Inspection Chart:
Visual Inspection Chart
2. Inspect to determine if any of the mechanical concerns apply.
- All of the accessories should be rotatable by hand in the unloaded condition. If not, inspect the accessory.
Drive belt chirp is a regularly occurring chirping noise that occurs due to:
- pulley misalignment.
- excessive pulley runout.
It can be a result of a damaged pulley or an incorrectly replaced pulley that was not correctly aligned.
To correct drive belt chirp:
- determine the area where the noise comes from.
- check each of the pulleys in that area with a straightedge to the crankshaft pulley for front accessory drive.
- look for the accessory pulley to be out of position in the fore/aft direction or at an angle to the straightedge.
Drive belt squeal is an intermittent noise that occurs when the drive belt slips on a pulley during certain conditions such as:
- engine start-up.
- rapid engine acceleration.
- A/C clutch engagement.
- NOTE: If fluids get on the drive belt (this includes power steering fluid, engine coolant, engine oil or air conditioning system lubricant), clean the drive pulleys with soap and water and thoroughly rinse with clean water. If no apparent damage has occurred, a new drive belt does not have to be installed.
NOTE: If the drive belt tensioner arm does not rotate freely without binding, the drive belt tensioner is worn or damaged. If the drive belt is outside the installation wear range window, install a new drive belt. A drive belt that is too long will allow the drive belt tensioner arm to go all the way to the arm travel stop under certain load conditions, which will release tension to the drive belt.
3. Inspect for drive belt cracking/chunking/wear.
4. If the concerns remain after inspection, determine the symptoms. GO to Symptom Chart. Symptom Related Diagnostic Procedures
Under severe operating conditions (high temperature, low humidity), drive belt rib cracking can occur at less than 96,000 km (60,000 miles). Drive belt rib cracking (cracks across grooves):
- is not a reason for concern.
- has no detrimental effect on drive belt performance.
Cracks parallel to grooves are acceptable.
The drive belt is still perfectly functional until rib chunking occurs. Drive belt chunking is where the rubber material actually chunks out between the cracks. A new drive belt should be installed if chunking occurs.
V-Ribbed Serpentine Drive Belt With Cracks Across Ribs
V-Ribbed Serpentine Drive Belt With Chunks of Rib Missing
5. If the concern(s) remains after inspection, determine the symptoms. GO to Symptom Chart.