A powerful and reliable tractor MTZ It refuses to start at the most inopportune moment, familiar to many mechanics. Most often, the problem lies not in a fatal breakdown, but in a banal violation of the sequence of actions or a minor malfunction, which is easy to eliminate in the field. The engine may not catch due to air entering the fuel system, a discharged battery or problems with the starter. Understanding the physics of diesel combustion helps you find the root of the problem more quickly.
Before we begin a deep diagnosis, it is necessary to exclude the human factor and simple technical omissions. Fuel level check And the state of the battery terminals takes only a couple of minutes, but often these actions bring the technique back to life. If simple methods did not help, you should move to the system analysis of nodes and assemblies. In this article, we will discuss in detail the main reasons for the failure of the engine of tractors of the Belarus family and methods of their elimination.
Problems with battery and starter
The most common reason why a tractor does not start is a weak starter current. A diesel engine requires considerable effort to turn the crankshaft, especially if the oil viscosity is high. If when you turn the key you hear only a quiet click or the starter rotates the flywheel sluggishly, first of all check. battery. Oxidized terminals create high resistance, not allowing the necessary current to be transferred to the electric motor.
Owners often forget about the condition of the contact connections. Dirt, oxides and weakened bolts negate the charge of even a serviceable battery. It is necessary to remove the terminals, clean them to a metallic shine and tighten them tightly. It is also worth checking the mounting of the starter himself: if he is poorly screwed, his gear may not be engaged with the flywheel, issuing a characteristic grinding.
- 🔋 Check the electrolyte level in the battery banks and, if necessary, add distilled water.
- ⚡ Measure the voltage at the terminals under load – it should not fall below 9-10 volts when trying to start.
- 🔧 Clear the contacts of the starter relay and check the integrity of the supply wires for breaks.
⚠️ Note: Do not attempt to start the engine from the pusher on tractors with a turbocharged engine or complex transmission without experience. This can lead to rupture of the timing belts or damage to the gears of the trigger gear (if installed).
Air in the fuel system and low quality diesel
The diesel engine works by ignition of the fuel from compression, and the presence of air in the mainline makes this process impossible. If the tractor has been standing for a long time or has run out of fuel, air enters the system, creating air traffic jams. High pressure fuel pump (PHP)TNVD) cannot pump gas and the nozzles no longer supply the fuel to the cylinders. Visually, this manifests itself as the engine’s operation with interruptions before a full stop or a complete start failure.
Fuel quality also plays a critical role. In winter, the use of summer diesel fuel leads to paraffinization and blockage of filters. Even in summer, water or dirt can be in the tank, which will instantly disable plunger vapors. Before each season, it is recommended to drain the suck from the fuel filters-sludges.
To remove air, you need to pump the system manually. On the filters of fine and rough cleaning there are special screws-pumping. Unscrewing them, you need to pump fuel with the lever of the pump until a clean diesel fuel without bubbles goes. Then they wrap the screws and try to start the engine.
Always have a transparent hose at hand to connect to the pumping fitting - so you will see the moment of air exit, without staining your hands with fuel.
Failure of the starting engine (PD-10)
Tractors. MTZ-80/82 and their modifications are often equipped with a starting engine PD-10The one that runs the main diesel. If the starter does not start, the tractor will remain standing. The main problems here are related to the ignition system, the quality of the fuel mixture and the condition of the piston group. The gasoline motor is sensitive to the soak on candles and the violation of the gap between the electrodes.
A common cause of failure is the re-enrichment of the mixture. If you repeatedly turned the starter without a result, the candles could "fill" with gasoline. In this case, they must be twisted, dried and calcined on fire to remove the remains of oil and soda. You should also check the compression: if it is low, the mixture will not ignite.
The ignition system requires special attention. The interrupter-distributor (trumbler) must be dry and clean. The entry of moisture on the lid or high-voltage wires causes a breakdown of the spark on the mass. The ignition advance angle must also be set correctly, otherwise the engine will shoot at the muffler or not develop revs.
- 🕯️ Check the gap between the electrodes of the spark plug - it should be 0.6-0.7 mm.
- 🔥 Make sure the spark is powerful and pierces the mass from a distance of 5-7 mm when scrolling.
- 🛢️ Keep an eye on the proportion of oil and gasoline in the mixture for the PD-10 two-stroke engine (usually 1:15 or 1:12).
What if PD-10 catches but does not keep pace?
Most likely, the problem is in the carburetor or sucking air through the crankshaft oal. Check the throttle adjustment and tightness of the crankcase. Often helps to replace the pads under the carburetor.
Fuel and injectors
If the starter cheerfully turns the flywheel, but there are no flashes in the cylinders, the problem may lie in the fuel equipment. Nozzles. They must spray the fuel in the form of a fine fog ("torch"). If a jet pours from the nozzle or drips, ignition will not occur. This is due to wear of the sprayer or improper injection pressure.
Check nozzles are carried out on a special stand, but in the field you can evaluate their work visually, turning from the engine. It is also worth paying attention to the work of plunger pairs of TNVD. When these parts are worn, the pump does not create the necessary pressure to open the nozzle needle at the right time.
| Symptoms. | Probable cause | Elimination method |
|---|---|---|
| There's smoke from the exhaust pipe, no launch. | Late ignition or low compression | Check injection timing, valves. |
| There's no smoke at all. | No fuel supply. | To upgrade the system, check the TNVD |
| White smoke when scrolling | Fuel is supplied but not burned. | Check the nozzles and compression |
| Black smoke | Re-enriched mixture | Setting up the TNVD, checking the air filter |
☑️ Diagnostics of the fuel system
Compression and valve mechanism
To ignite diesel fuel, the air in the cylinder must be compressed to a temperature of 600-700 degrees. If compression It is low, and this temperature cannot be reached. The compression drop is most often caused by wear of piston rings, laying of rings in grooves or loose adjoining of valves to the saddles.
The gaps in the valve mechanism are a critical parameter. If the gaps are too small (the valve is clamped), they will not close tightly and gases will break into the exhaust manifold or crankcase. This is especially true for engines that have undergone major repairs or long-term operation without adjustment. Thermal clearances should be adjusted on a cold engine.
Checking the compression is made by a compressometer, screwed in instead of the nozzle. The normal value for tractor diesels is considered to be pressure above 20-25 atmospheres (specific figures depend on the engine model). D-240/243/245). The significant difference between cylinders indicates a local problem.
⚠️ Warning: Adjusting the valves "hot" will lead to incorrect readings of gaps. After cooling the engine, the valves may remain clamped, which will lead to their burnout and damage to the piston.
Seasonal features of the launch in winter
Winter is the most difficult test for any technique. Low temperatures increase the viscosity of the oil, which creates a huge resistance to the rotation of the crankshaft. Even a serviceable battery at minus 20 degrees loses up to 50% of its capacity. Therefore preheating It is not just a convenience, but a necessity to preserve the engine life.
The use of the starting fluid ("quick start") requires extreme caution. Excessive injection of aerosol into the intake manifold can cause a hydrostroke or even an explosion in the intake pipeline, damaging sensors and gaskets. It should be used with short-term pressing only when the starter is actively rotating.
In severe frosts, it is recommended to use preheaters of cooling liquid or at least warm the engine pallet with hot water / heat gun. The oil in the crankcase must be seasonal (winter), otherwise the starter simply will not be able to turn the crankshaft at the normal speed required for start-up.
Winter launch requires a comprehensive approach: a serviceable battery, winter oil, a warmed-up engine and high-quality fuel. Ignoring any of the factors can lead to failure of the technique.
Electrical circuits and sensors (for modern modifications)
Modern modifications of tractors "Belarus" are equipped with electronic control units and sensors that can block the start in emergency modes. For example, an oil pressure sensor or clutch pedal position sensor (for tractors with a joystick or reverse) can break the starter circuit. If the starter is silent completely, it is worth checking the fuses and relay in the mounting unit.
Oxidation of contacts in sensor connectors is a common problem when operating in conditions of high humidity and dirt. Spraying contacts with a spray cleaner (contact) often helps restore the normal operation of the electrician. It is also worth checking the "mass" of the engine - a wire connecting the body to the cylinder block. Its cliff or poor contact will block all electronics.
- 🔌 Check the integrity of the fuses responsible for the starter circuit and ECU.
- 🧹 Blow in compressed air and spray the main electrical connectors.
- 🔋 Make sure there is a reliable contact of mass between the engine and the tractor frame.
Frequently Asked Questions (FAQ)
Why does the tractor start and stop immediately?
Most often, this indicates water entering the fuel tank or a strong clogging of the fuel filter. Also, the cause may be air sucking through the densities in the fuel line, because of which after the production of fuel from the filter, the engine stops.
Can I start MTZ from a tow?
Start a diesel engine from a tow can be, but undesirable, as it creates shock loads on the gearbox and transmission parts. This should be done only in emergency cases, having previously warmed up the engine in other ways and making sure that the oil in the crankcase does not freeze.
What compression should be for a confident start?
For a confident start of a diesel engine tractor compression must be at least 20-22 atmospheres. At values below 18 atmospheres, cold-starting is virtually impossible, especially in winter.
What if the starter clicks but doesn’t spin?
A click indicates the retracting relay is working, but the lack of rotation indicates poor contact inside the relay, wear of the starter brushes or, most often, a discharged battery. Try to close the terminals of the starter directly with a screwdriver (with caution) - if it twists, then the problem is in the relay or wiring.