The situation when you turn the ignition key, and in response you hear only a plaintive buzzing or a full pin, and the engine does not catch, is familiar to many car owners. This is a classic sign that the starting system has lost the necessary traction. Often drivers are faced with the fact that starter spins idly, without transmitting rotation to flywheel engine. The problem lies not in the electrical part, but in the mechanical connection, which must firmly fix the gear to the engine ring.
If bendix (overrunning clutch) cannot engage the flywheel teeth, you will hear a characteristic sound of free rotation. This may be caused by worn gears, a broken return spring, or a jammed mechanism. Ignoring this problem will lead to complete failure of the starter or, worse, to destruction of the flywheel crown, the repair of which will require dismantling the gearbox.
The operating principle of the starting mechanism and the role of the overrunning clutch
To understand why slippage occurs, it is necessary to consider how the torque transmission mechanism is designed. When you turn the key, an electromagnetic switch (traction relay) pushes the gear forward so that it engages the teeth flywheel. At the same time, power is supplied to electric motor starter.
Overrunning clutch, or bendix, plays a critical role in this process. It allows the gear to rotate faster than the starter shaft when starting, but instantly locks up if it tries to rotate in the opposite direction after the engine has already started. If this mechanism fails, rotation is not transmitted to the engine, and you observe a picture of “easy cranking”.
There are several failure scenarios for this system:
- 🚫 Wear of the Bendix gear teeth, which is why they cannot grip the flywheel crown.
- 🚫 Loss of spring elasticity, which should press the gear to the flywheel.
- 🚫 Contamination of the mechanism with lubricant or wear products, preventing retraction.
Main mechanical causes of failure
The most common reason why a kickstarter turns easily is physical wear on the gear. Over time, the teeth Bendix wear off, become sharp or chip. As a result, even when fully extended, they do not engage with the flywheel teeth and spin. This is especially true for cars with high mileage or those that are often used in harsh conditions.
An equally dangerous problem is jamming of the mechanism itself. Dust, dirt, or old, thickened grease may get inside the housing. This creates excess friction and the gear simply cannot advance the required distance. In this case, the starter motor rotates, but the gear remains in a “sleeping” position inside the housing.
It is important to note that the problem may be not only in the starter itself, but also in the associated units. If the flywheel crown is worn out or damaged, even if it is in good working order bendix will not be able to create a reliable connection.
- The starter hums, but does not turn the engine
- Metal scraping is heard
- The starter turns, but very slowly
- Nothing happens
Diagnosis of faults in garage conditions
Before disassembling the unit, you should make sure that the problem is mechanical and not electrical. First check the battery charge. A weak current may not fully activate the solenoid relay, and the gear will not reach its working stroke. Use a multimeter to check the voltage at the terminals when attempting to start.
If everything is in order with the electrics, it is necessary to conduct a visual inspection. Remove the starter from the car and check the condition of the gear. It should be clean, without chips or signs of heavy wear. Try turning the gear by hand: it should rotate freely in one direction and be blocked in the other. If it spins in both directions - the mechanism bendix dead.
For accurate diagnosis, you can use the following algorithm:
- 🔍 Clean the starter housing from dirt and oil.
- 🔍 Check the gear movement by hand, simulating the operation of a retractor relay.
- 🔍 Inspect the flywheel crown through the technological window (if there is access).
☑️ Check before removal
How to replace bendix and eliminate slippage
If diagnostics confirm wear of the overrunning clutch, it will require replacement or repair of the entire assembly. In most cases it is easier and cheaper to buy a new one bendix assembled rather than trying to restore old bearings and springs. The replacement process requires care and a set of suitable tools.
First you need to unscrew the mounting bolts holding the bendix cover. Be careful, as there are springs and latches underneath that could pop off. After disassembly, remove the old mechanism and clean the starter shaft of old grease. Install the new part, making sure that it fits tightly onto the shaft and without play.
Important note: when assembling, do not use too much lubricant. Excess oil can leak into the motor windings, causing a short circuit or slippage. It is enough to apply a thin layer of special high-temperature grease to the shaft and gear.
What to do if there is no new Bendix?
As a last resort, you can try to clean the gear teeth with a file, but this is a temporary measure. Also, some craftsmen use the method of “rolling” the teeth, but this requires professional equipment and skills, otherwise the gear can be completely damaged.
Flywheel crown repair and other nuances
Sometimes the reason for cranking is not in the starter, but in the flywheel. If the teeth on it are worn out or chipped, the new Bendix will not cope either. In this case, you need to remove the gearbox and inspect the crown. If the damage is minor, you can try turning the crown 180 degrees (if it is removable) or welding and sharpening the teeth in a workshop.
Before removing the transmission, be sure to mark the position of the flywheel relative to the crankshaft if balancing is required, although in most cases this is not critical for passenger cars.
In some cases, the problem may be that the starter is not installed correctly. If the gasket between the starter and engine block is too thick or missing, the clearance between the gear and flywheel will be too large. This will result in the teeth simply not being able to engage.
Pay attention to the starter mounting. Loose bolts can cause the rotation axis to shift, causing the gear to only partially engage the flywheel. This causes vibration and rapid wear of both elements.
Prevention and selection of quality spare parts
To avoid a repeat of the situation, it is important to operate the starting system correctly. Do not hold the key in the “Start” position for more than 10-15 seconds. If the engine does not start, allow the starter to cool, otherwise the winding will overheat and the bendix may become deformed from overheating.
When choosing spare parts, give preference to proven brands. Cheap analogs are often made of soft alloys that wear out quickly. Look for products marked OEM or reputable manufacturers of automotive components.
Comparison of popular bendix manufacturers:
| Manufacturer | Quality of materials | Service life | Price |
|---|---|---|---|
| Original (OEM) | High | Long | High |
| ASA | Average | Medium | Average |
| Chinese analogues | Low | Short | Low |
Regularly checking the condition of the starter and flywheel ring during scheduled maintenance will help avoid sudden failure of the starting system at the most inopportune moment.
Features of cold work
In winter, the problem of “easy turning” becomes more acute. Thick engine oil creates enormous resistance to crankshaft rotation. The starter has to exert maximum effort, which accelerates wear on the bendix. If the mechanism already has a little wear, in the cold it simply will not be able to overcome the oil resistance.
In such conditions, it is critical to warm up the engine before starting or use preheaters. This will reduce the load on the starter and allow the mechanism to operate in a more gentle manner. It is also worth making sure that the battery is fully charged, as its capacity decreases in the cold.
If you notice that the starter has begun to work “softer” and easier than usual, but the engine does not start, this is an alarming signal. Most likely, the clutch can no longer create the required engagement force.
Why does the starter turn more quietly in winter?
In cold weather, the viscosity of the oil increases, which requires more torque. If the starter cannot provide this torque due to wear or a weak battery, it begins to “slip” or work intermittently.
FAQ: Frequently asked questions from owners
Why does the starter turn, but the engine does not catch?
This may mean that the bendix is worn or seized and the gear is not engaging the flywheel. Damage to the teeth of the flywheel ring is also possible.
Is it possible to start the engine if the bendix is slipping?
No, it will not be possible to transfer rotation mechanically. The only temporary option is a pusher or tug, but this is only possible for manual transmissions and with a working clutch.
How much does it cost to replace a bendix?
The cost varies depending on the car model and the manufacturer of the part. On average, replacement work takes 1-2 hours, and the part itself costs from 1,500 to 5,000 rubles.
How often should the starter be replaced?
The starter does not have strict replacement regulations. He serves as long as his resources allow. On average, the service life is 150-200 thousand kilometers, but this depends on operating conditions.
⚠️ Attention: Do not try to start the engine by constantly holding the key in the “Start” position for more than 10 seconds. This can lead to overheating of the winding and complete failure of the starter.
⚠️ Warning: If you hear scraping metal when trying to start, stop immediately. This is a sign of destruction of the flywheel or bendix teeth, and further operation will lead to expensive repairs.
⚠️ Attention: Never install a bendix without checking the condition of the starter shaft for wear, otherwise the new mechanism will quickly fail.