Belt specialist Gates has issued some new advice to technician on the pitfalls of incorrectly interchanging drive system belts on its Gates Tech Zone on-line resource.

Gates says that visually two different belts often look the same but have a different part numbers. Some technicians may be tempted to believe these belts are interchangeable. However Gates makes it clear they are definitely not.

Even if the belts have the same number of teeth they are not substitutable as on many timing belts, the pitch between the teeth is exactly the same and you may not be able to spot any differences with the naked eye. There may, for instance, be small variations in tooth profile, tooth angle and depth. In addition, the tensile cord or the fabric covering the teeth may be made from a completely different material. Lastly, the rubber composition, the strength, thickness or temperature resistance may vary from one timing belt to another.

If the wrong belt is used problems may arise such as premature timing belt failure, with symptoms such as tensile failure, tooth shear, tooth wear, hollowed teeth or land wear. This, in turn, may cause catastrophic engine damage.

Gates also point out that correct selection is also essential with accessory belts. These  are designed to meet the specifications set for particular engines and different belt types are needed to accommodate variations in OE design such as power needed to transmit, wrap angles/pulley diametres, belt tension, an absence of tensioners, etc. Gates stretch-type belts, called Stretch Fit belts, always have a SF at the end of the part number and generally will need a tool for installation. When a 4PK738SF is prescribed, you simply can’t install a 4PK738 as it is not suitable for the job.

Gates Tech Zone offers a wealth of useful tech-tips and guides to technicians, including a complete Accessory Belt Drive System Trouble Shooting guide which is downloadable in PDF format free of charge. Just go to www.gatestechzone.com/en and register to access this information for free.