Component Tests and General Diagnostics
COMPONENT TESTSBELT TENSIONER
Note: Tensioners are shown in free-state position against arm travel stops.
Drive Belt Tensioner/Belt Length Indicator With A/C
Drive Belt Tensioner/Belt Length Indicator Without A/C
Automatic tensioners are calibrated at the factory to provide the correct amount of tension to the belt. Unless a spring within the tensioner assembly breaks or some other mechanical part of the tensioner fails, there is no need to check tensioners for proper tension.
The only mechanical check that need be made, if you have any doubt about the tensioner function, would be to remove the belt in the area of the tensioner, to avoid belt contact, then using the proper tool, rotate the tensioner from its relaxed position through its full stroke and back to the relaxed position to make sure that there is no "stick, grab, bind," and to make sure that there is tension on the spring. It is a normal condition for the tensioner to be moving, under certain conditions, when the engine is running. If the tensioner meets these criteria, it should be assumed to be a good tensioner.
DRIVE BELT MISALIGNMENT
CAUTION: Incorrect drive belt installation will cause excessive drive belt wear and may cause the drive belt to come off the drive pulleys.
Non-standard replacement drive belts may track differently or improperly. If a replacement drive belt tracks improperly, install a new drive belt to avoid performance failure or loss of belt.
With the engine running, check drive belt tracking. If the (A) edge of the drive belt rides beyond the edge of the pulleys, noise and premature wear may occur. Make sure the (B) drive belt rides correctly on the pulley. If a drive belt tracking condition exists, proceed with the following:
Visually check the drive belt tensioner for damage, especially the mounting pad surface. If the drive belt tensioner is not installed correctly, the mounting surface pad will be out of position. This will result in chirp and squeal noises.
^ With the engine running, visually observe the grooves in the pulleys (not the pulley flanges or pulley front surfaces) for excessive wobble. Install new components as necessary.
^ Check all accessories, mounting brackets and the drive belt tensioner for any interference that would prevent the component from mounting correctly. Correct any interference condition and recheck belt tracking.
^ Tighten all accessories, mounting brackets, and drive belt tensioner retaining hardware to specification. Recheck the drive belt tracking.
DRIVE BELT NOISE
Drive belt noise 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 or A/C clutch engagement.
Drive belt noise can occur under the following conditions.
1. The A/C discharge pressure goes above specifications, causing one of the following:
^ The A/C system is overcharged.
^ The A/C condenser core airflow is blocked.
2. The A/C OFF equalized pressure (the common discharge and suction pressure that occurs after several minutes) exceeds specifications.
3. Any of the accessories are damaged or have a worn or damaged bearing or internal torsional resistance above normal. All accessories must be rotatable by hand in the unloaded condition. If not, inspect the accessory.
4. Fluid gets on the drive belt. This includes power steering fluid, engine coolant, engine oil or air conditioning system lubricant. If fluid gets on the drive belt during repairs, clean the drive belt with soap and water, and thoroughly rinse with clean water. The drive belt does not have to be replaced if no apparent damage has occurred.
5. NOTE: The drive belt tensioner arm must rotate freely without binding.
The drive belt is too long. 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. If the drive belt tensioner indicator is outside of the wear range window, install a new drive belt.
6. The drive belt tensioner is worn or damaged.