Particle tearing
Observation
- Material is tearing away from the belt and accumulating in the ribs.
Timing belts are essential to the engine operation. Timing belts wear over time, which means they may fail, causing serious damage to the engine. Our experts share their practical advice on maintaining and replacing timing belts. These recommendations will help prevent breakdowns and ensure longer life for timing system components.
Causes
- Pulley misalignment
- Pulley wear
Advice
- Follow the general recommendations for installation
- Check the engine cooling
- Check the condition of the pulleys, change the belt, check the tension applied by the tensioner
- A belt must be dry and free from all traces of oil , grease or coolant, all of which can damage the struture of the belt
Causes
- Excessive tightness
- Worn pulleys
- Operating temperature too high
Belt cracking
Observation
- Presence of small visible cracks.
Causes
- Overheating of the rubber due to excessive tension
- Insufficient tension causing the belt to slip on the pulleys, leading to overheating
Advice
- Replace the belt
- Comply with the belt tension specified by the manufacturer
- Use an electronic belt tension gauge (if necessary)
- Check for overheating of the other components
- Inspect the condition of the casing
- Check the engine cooling system
Causes
- Temperature too low or too high
- Ageing of the belt
- Contact with a foreign object or misalignment
Teeth detachment / teeth tear-off
Observation
- Tearing of the teeth.
Causes
- Accelerated ageing due to heat or abnormal loading
- Possible presence of foreign bodies in the grooves
Advice
- Replace the belt
- Check and repair the transmission system
- Ensure the engine protection covers are present and correctly positioned
Causes
- Partial or complete seizure of a component in the engine timing system
- The teeth are torn away from the belt core: insufficient belt tension or contamination by liquids
Flank wear
Observation
- Premature wear on one side; the cord may be frayed. Significant noise.
Causes
- Fitting carried out using an unsuitable tool (screwdriver)
- Belt misaligned during pulley installation
Advice
- Replace the belt and realign the pulleys
- Check the condition of all the components in the auxiliary and timing systems
- Strictly follow the installation procedure recommended by the manufacturer
Causes
- Misalignment of the pulleys and/or tensioners
- Contact with a foreign object
Irregular rupture
Observation
- Transverse tears in the belt.
- Damage to the back with small holes present and a risk of fraying.
Causes
-
Ingress of small stones due to the absence of a protective cover
Advice
- Replace the belt
- Check the transmission system
- Follow the recommended installation instructions
- Check the wear level of the engine pulleys
Causes
- Over-tensioning of the belt
- External component blocked
- Solid or liquid contamination
Clean break
Observation
- Clean tears in the belt
Causes
- Foreign object trapped between the belt and the pulley or pulleys
- Excessive tension
- Damage to the internal structure of the belt (fibreglass cord)
- Use of an unsuitable tool (screwdriver)
Advice
- Replace the belt
- Check the transmission system
- Follow the recommended installation instructions
- Check the wear level of the engine pulleys
Causes
- Defective materials
- Use of an unsuitable tool (screwdriver)
- Bending of the belt before and/or during installation
- Solid or liquid contamination
Insufficient tension or external component blocked
Observation
- Back of the belt with very pronounced wear
Causes
- Belt slipping on a pulley due to incorrect belt tension during operation
- Defective alternator pulley (OAP)
Advice
- Replace the belt and check the complete routing around the belt
- Check the tension applied by the tensioner pulley
- Follow the general installation recommendations
Causes
- Excessive tension
- External components blocked (water pump)
Timing belts
NTN, as a premium manufacturer, supplies timing belts exclusively in kit form. These OE-quality belts meet the original specifications (Teflon, Kevlar or even belt-in-oil technology).
Our recommendations for garage owners:
When replacing the engine timing system, the pulleys/rollers must be changed as well as the belt. If the water pump is driven by this belt, it must also be replaced.
All our kits include:
- Tensioner and/or idler pulleys
- A timing belt, with or without water pump (KDP or KD)
- The necessary fastening hardware
You will find all the tools you need for timing kits with the OM9901 and OM9695 tool trolleys.
Modern vehicles feature increasingly complex auxiliary systems, with higher belt tension. It is essential to replace all the auxiliary components. Indeed, the pulleys and the water pump, just like the belt, are wear parts. Any component that is not replaced may damage the belt or, in the worst case, the engine. Note that 40% of water pumps are driven by the auxiliary belt.
Our recommendations for garage owners:
- Any removed belt (timing or auxiliary) must be replaced, along with its tensioner pulley.
- After replacing the pulley or pulleys, make sure you install the belt in the correct direction (marking direction always visible), while applying the correct tension in accordance with the manufacturer’s specifications.
