The internal combustion engine is a complex mechanism where each element plays a critical role, but it is the belt transmissions that often remain in the shadows until the moment of breakage. A driver may not look under the hood for years until he hears a whistle or the battery light. However, understanding which belts in the car in the engine do the job of transferring rotation is a basic skill for any car owner looking to avoid costly repairs.
The main task of these elements is to transfer torque from the crankshaft to various auxiliary units and gas distribution mechanisms. Despite their similarity, they are radically different in design, materials and operating conditions. Mistaking the choice or ignoring the timing of the replacement of one of them can lead to a car stop on the track or even to major repairs of the engine.
In this article, we will take a closer look at what types of belts are used in modern cars, how they differ, and how to understand what part life is coming to an end. You will learn about the intricacies of the design that are hidden from view, and understand why saving on this consumable is unacceptable.
The belt of the engine: the heart of the engine and its protection
The most important element in the belt system is garnet (gas distribution mechanism). It is he who synchonizes the work of the cranked and camshafts, ensuring the opening and closing of the valves at strictly defined moments in time. If this belt breaks or jumps on several teeth, the pistons can hit the valves, leading to fatal consequences for the engine.
Structurally, the belt of the GRM is a closed ring with teeth on the inside, which exactly coincide with the gears of the shafts. To enhance the strength inside the rubber base is often embedded cord of fiberglass, Kevlar or metal. Modern products such as Contitech or Gates, covered with a special composition that protects against the effects of oils and high temperatures that inevitably occur in the area of operation of the motor.
The resource of the belt is strictly regulated by the manufacturer of the car and usually ranges from 60 to 120 thousand kilometers of mileage or 5 years of operation. However, the actual lifespan may be shorter if the vehicle is often used in traffic jams or in heavy dust conditions. Visually check its condition is difficult, as it is often covered with plastic casings, but when cracks appear in visible areas or the end part is stratified, replacement is required immediately.
Always change the belt along with stretch and bypass rollers, as wear of roller bearings can lead to a break of a new belt.
⚠️ Warning: Never try to pull or loosen the belt manually without a special tool - tension violation is guaranteed to lead to a break or cut teeth when the engine is running.
Polyclinic belt of attachments
The second most important element is polyclinThis is often referred to as a generator belt or auxiliary units. Unlike the GRM, it operates from the outside and drives a generator, a water pump (pump), an air conditioner compressor and a power steering pump. Its design resembles a tank track: on the inside there are longitudinal ribs (wedges), which provide excellent grip with pulleys even at high loads.
The material for such belts is a special ethylene-propylene rubber (EPDM), which is resistant to heating and cracking. However, over time, it loses its elasticity. If you hear a piercing whistle when starting the engine in cold weather or when the air conditioner is turned on, this is the first sign that the belt is slipping. Often the cause is not only wear of the rubber itself, but also the hit of technical liquids on it or the weakening of the tensioner.
In modern engines, such as series Ecoboost from Ford or TSI Volkswagen uses an automatic tensioner that does not require manual adjustment. However, the tension mechanism also has its own resource and can jam. When replacing the belt of the attachment, always check the ease of rotation of all pulleys - a jammed bearing of the generator or pump is able to break a new belt in a matter of kilometers.
Old-style wedge belts
On cars of old years of release, as well as in some truck models, you can still find classic models. wedge-belt trapezoidal section. Unlike modern polyclinic analogues, each such belt is responsible for one or two units. For example, a single belt can only rotate a generator, while the other can only rotate a pump and a cooling fan.
The main disadvantage of such a system is the need for periodic manual adjustment of tension. Over time, the belt is stretched, and it has to be tightened, shifting the generator along the guides. If this is not done, the engine will start slipping and overheating due to the slow circulation of antifreeze. Excessive tension leads to accelerated wear of bearings of hinged units.
Despite their archaic nature, such systems are reliable and cheap to maintain. Replacement is done quickly, and diagnosis can be carried out visually without removing protective casings. When inspecting, pay attention to the state of the side faces: if they have become glossy or deep cracks have appeared on them, the part must be replaced.
Materials and production technologies
The quality of the belts depends on the materials used in their production. The basis of modern products is synthetic rubbers, which are not afraid of temperature changes from -40 to +100 degrees Celsius. However, the secret of durability lies in the reinforcement cord. In premium segments, for example, in belts Dayco or BoschKevlar fiber is used, which is practically not stretched during operation.
An important element is also the coating of teeth. It reduces friction and noise during operation, and also protects the base from fine dust and abrasive particles. Some manufacturers add graphite spraying, which serves as a dry lubricant. This is especially true for high-speed engines, where friction can cause local rubber overheating.
Why can’t we use universal belts?
Universal belts often have averaged geometric parameters, which can lead to the wrong pulley angle and rapid wear. Always choose a belt by catalog number for your car model.
The manufacturing technology also includes a vulcanization process that gives the rubber its final shape and strength. A breakdown in the technology at the manufacturer causes the belt to be stripped in a few thousand kilometers. Therefore, buying cheap analogues of unknown brands on the market is a lottery with a high risk for the engine.
Symptoms of wear and diagnosis
To determine the condition of the belts can be not only by mileage, but also by indirect signs. The most obvious of these is the noise. Whistling, squealing or rustling in the under-hood space often indicate problems with the drive of attachments. However, in the case of a belt, there may be no noise at all, since it works in an oil bath (in some engines) or is closed with deaf casings.
Visual inspection is the mechanic’s best friend. When removing the housing of the HRM, you must pay attention to the following defects:
- 🔴 The presence of microcracks on the inner surface of the belt, especially at the base of the teeth.
- 🟢 Oiliness or the presence of antifreeze on the surface, which indicates a loss of sealability of the ossicles.
- 🔵 The separation of end parts or the appearance of "fringe".
- 🟡 Cutting or deforming teeth, which indicates problems with the tensioner.
For polyclin belts, the depth of the grooves is critical. If it has decreased by more than 50% of the nominal value, the belt is considered worn out. Also a sign of aging rubber is a change in color: a black, fluffy surface instead of matte black indicates that the material has lost elasticity and will soon begin to crack.
⚠️ If you find traces of engine oil on the belt, it is mandatory to replace it, even if it is new. The oil corrodes rubber, turning it into porridge in a matter of days.
Table: Comparison of belt types
To organize the information and clearly understand the differences, let’s turn to a comparative table. It will help you quickly navigate the types of drives installed on various components of the car.
| Parameter | The HRM belt | Polyclin belt | Wedge belt |
|---|---|---|---|
| Appointment | Synchronization of shafts | Power of attachments | Drive of individual units |
| Consequences of the cliff | Engine capremont | Stopping car, AKB discharge | Failure of a particular node |
| Average resource | 60-120 thousand. km | 40,000-800,000. km | 20-40 thousand. km |
| Construction | Toothy, closed. | Ribbed, multi-arm | trapezoidal profile |
Breaking the belt of the timing almost always leads to expensive repairs of the engine, while a break in the belt of the generator will only immobilize the car until the arrival of the tow truck.
Replacement process and important nuances
Replacement of belts is a procedure that requires accuracy and adherence to technology. For work with the GRM, special equipment is often needed: shaft locks, dynamometer keys and removers. An error when placing labels even on one tooth can disrupt the gas distribution phases, which will lead to power loss, increased fuel consumption and unstable operation of the engine at idle speeds.
Here is an example of an algorithm for replacing a polyclin belt, which can be performed in a garage with access:
- 🔧 Relax the tensioner with a key or special device.
- 🔧 Remove the old belt by remembering or photographing the scheme of its passage on the pulleys.
- 🔧 Check the free movement of all pulleys (generator, pumps, GUR) - they should rotate easily and without noise.
- 🔧 Install a new belt, making sure the ribs are exactly in the streams of pulleys.
- 🔧 Smoothly release the tensioner and check the tension.
☑️ Checklist before engine start
After installing a new belt, experienced masters recommend manually turning the crankshaft on two full turns. This is done to make sure that the valve does not meet the pistons, and the belt has fallen into place without distortion. Only after this test can the engine be started.
Frequent questions and answers
Can I replace the belt without experience?
It's not recommended. An error in the installation of tags or improper tension will lead to the meeting of valves with pistons at start-up, which will require major repairs to the engine. Savings on services in this case does not justify the risks.
How often should the generator belt be changed?
The recommended interval of replacement of polyclin belt is 60 000 km or 4 years of operation. However, it is desirable to carry out a visual inspection at each scheduled maintenance of the car.
Why does the belt whistle after replacement?
Whistling can occur due to oil hitting the belt, weak tension or the use of a low-quality part. Also, the reason may be a worn bearing of the tension roller, which was not replaced along with the belt.
Does driving style affect the life of the belts?
Yes, aggressive driving with high engine speeds increases the load on the belt gears. Frequent accelerations and braking in the city wear belts faster than a calm ride on the highway.