The situation when the legendary Moskvich 412 Refusing to start, the owner often becomes stressful, especially if the car is used as a primary means of transportation or in rally rides. This car, despite its simplicity and reliability, requires precise system configuration, as the lack of electronics makes it dependent on the mechanical state of the nodes. Most often, the problem lies in the imbalance between the fuel supply and the quality of the spark, which is typical for carburetor engines.
Before opening the hood and grasping the tools, it is necessary to conduct primary visual and auditory diagnosis. Engine UZAM-412 He is rather unpretentious, but he does not tolerate negligence in service. If the starter spins sluggishly or does not spin at all, then it is too early to look for a problem in the carburetor or candles - first you need to ensure a normal current of the crankshaft scrolling.
In this article, we will discuss all the main scenarios why Moskvich 412 does not start, from the banal discharge of the battery to complex malfunctions of the gas distribution mechanism. We structure the information so that you can consistently rule out the causes, moving from simple to complex, and not waste time replacing the proper parts.
Primary diagnosis: starter and battery
Any diagnosis begins with an assessment of how the car behaves when turning the key in the ignition lock. If you hear only a quiet click or hum and the crankshaft is standing still, then the problem lies in the launch system. Battery battery This is the first thing to check, as even a fully serviceable engine will not start without a sufficient speed.
Pay attention to the state of the terminals. On older cars, contact oxidation occurs very quickly, creating a high transient resistance. Even if the light bulbs on the dashboard burn brightly, the starterβs initiation current may not pass through the oxidized terminals. Cleaning the contacts to a metallic sheen often solves the problem instantly.
β οΈ Warning: If the starter is making a sharp metal clang when trying to start, but does not rotate the engine, stop trying immediately. This may indicate engine jamming or a break in the bendix, and further scrolling will only finish the starter.
Testing the tension of the generator belt is also important, although it affects the start indirectly. If the belt is twisted, it creates additional resistance to the rotation of the crankshaft, which is critical for a tired battery. Weaken the mounting of the generator and check the tension with your finger - the deflection should be 10-15 mm.
In some cases, the starter may turn the engine, but too slowly to ignite the mixture. The carburetor engine requires a certain air flow rate in the intake manifold to create the desired air flow rate. thinning. If the starter is "tired" (wearing out the bushings, brushes or windings), it must be removed and defective or replaced.
β οΈ Note: When checking the starter circuit, use only serviceable wires with a cross section of at least 10-16 mm2. Thin wires can melt or cause a voltage drop, because of which the starter will not develop the desired power.
Problems with the ignition system: spark and timing
If the starter cheerfully rotates the crankshaft, but the engine is silent, the next most important is the ignition system. V Moskvich 412 It can be contact (with a interrupter) or contactless (with an electronic switch). First, you need to make sure that there is a spark on the central wire of the ignition coil.
Unscrew the central wire from the trambler lid, bring it to the "mass" (metal part of the engine) at a distance of 5-7 mm and ask the assistant to spin the starter. sparkle It should be bright, blue and with a characteristic crack. If there is no spark or it is weak, reddish, the problem is in the coil, switch or Hall sensor (depending on the modification).
- π₯ Contact group: On older models, the contacts of the interrupter are often burned or the gap is knocked down. The gap should be strictly 0.35-0.45 mm, checked by a probe when open cams.
- β‘ Capacitor: Failure of the capacitor in the trambler leads to a strong sparking of contacts and the loss of sparks on candles. Replace it at the earliest opportunity.
- 𧱠Angle of advance: Incorrectly exposed ignition (too early or later) will not allow the engine to start. Try turning the trampler slightly.
And we must not forget that spark-plug. Even if there is a spark on the central wire, it may not break through the gap of the candle due to the soak or improper gap of the electrodes. Turn the candles out: if they are wet and smell like gasoline, then the fuel is coming in, but not ignited. If dry, the problem is the supply.
How to check the ignition coil with a multimeter?
To check the primary winding, switch the multimeter to resistance measurement mode (200 ohms). The normal value should be within 2-4 ohms. For the secondary winding (mode 20 kΞ©), the norm is 6-9 kΞ©. If the resistance is towards infinity or zero, the coil is faulty.
Fuel system: petrol pump and carburetor
The third whale, on which the engine is kept Moskvich 412 - it's fuel. carburetor ozone or solex (if a replacement has been made) requires clean gasoline and stable pressure. If the candles are dry after long attempts to start, then the gasoline does not reach the cylinders.
First thing you do, check. fuel-pump. Disconnect the hose from the entrance to the carburetor and swing the hand-pumping lever. Gasoline should go a powerful pulsating stream. If the jet is weak or not, check the gas pump filter-sludge (glass) - it is often clogged with rust from the tank.
The most common problem of carburetor engines is overflow or lack of fuel. If you "fill" the engine (candles are wet, smells of gasoline), you need to blow out the cylinders. To do this, squeeze the gas pedal into the floor (opening the throttle) and spin the starter for 10-15 seconds. This will blow the combustion chambers with fresh air.
| Symptoms. | Probable cause | Action. |
|---|---|---|
| Candles are dry, no smell. | It doesn't pump the gas pump, the filter is clogged. | Blow the fuel line, replace the filter |
| Candles are wet, smells. | Carburettor overflow, no spark | Check the carburetor needle, check the spark |
| Black candles, tan. | Rich mixture, late ignition | Set up a carburetor, set the UZ |
| Candles are white, melted | Poor mix, early ignition. | Check the air suction, set up the carburetor |
Carburetor often gets a fuse. needle-valveThis causes the fuel level in the float chamber to become either critically low or the gasoline to pour continuously. It is also worth checking the integrity of the aperture pump β if it is torn, when pressed on the gas, the jet of gasoline will not fall into the diffuser, and acceleration (or start) will not occur.
βοΈ Diagnostics of the fuel system
Mechanical malfunctions and compression
If the fuel and electricity are fine, Moskvich 412 It doesn't start anyway, you'll have to dig deeper. An internal combustion engine is a pump, and if it has lost its tightness (compression), ignition of the mixture will become impossible. Low compression can be caused by wear of piston rings, burn-out of valves or breakdown of the gasket of the GBC.
A symptom of mechanical problems is often a "light" spin of the starter. If the engine spins too easily, without the characteristic resistance of compression strokes, then the gases go into the crankcase or cooling system. This may also be indicated by white smoke from the exhaust pipe or bubbles in the expansion tank when scrolling with a starter.
β οΈ Note: If a strong flow of gases (βsapuniteβ) is attempted to start from the oil filler neck, and the oil pressure has dropped to zero, further operation of the engine can lead to liners turning and bullies.
Checking the gas distribution phases is another important step. If the belt timing (on modifications with the belt) jumped on the tooth or cut the veneer on the gear drive (on chain motors), the valves will open out of time pistons. In this case, the engine may not start at all or work extremely unstable with the cotton in the carburetor.
Accurate diagnosis is required compressometer. Roll it into the candle hole and spin the starter until the arrow stops growing. For UZAM-412 normal compression is 9-11 kgf / cm2. The scatter between the cylinders should not exceed 1 unit. If the compression is much lower in one cylinder, pour 5-10 ml of engine oil there and repeat the measurement. If the compression increased - the problem in the rings, if it remained the same - the valve burned out.
External factors and seasonality
Owner Moskvich 412 It should be noted that this car, like any classic, is sensitive to weather conditions. In winter or in wet weather, start problems can be caused by condensation in the ignition system or freezing of condensate in fuel lines.
Special attention should be paid air-filter. If it has not changed for a long time and is soaked in oil or dust, the engine will "suffocate", getting too rich a mixture. In wet weather, moisture can settle on the trambler lid, creating conductive tracks, because of which the spark "goes away" to the mass, without reaching candles. Wipe the lid with dry rags and treat the WD-40 outside.
- βοΈ Winter launch: Use preheating or put the battery in the heat. Cold oil thickens, increasing the resistance to scrolling.
- π§οΈ Wet weather: Check the high-voltage wires for microcracks. In the dark you can see the "glow" of breaks in the isolation.
- βοΈ Heat: In summer, steam constipation is possible in the gas pump. Cover the pump with a wet cloth or cool it.
To improve the launch in wet weather, you can use the spray "Quick Start" (ether), but only briefly and with caution, so as not to cause a hydrostroke or detonation.
Algorithm of actions and final recommendations
Not to be confused by the multitude reasons why Moskvich 412 It is not necessary to act systematically. Chaotic replacement of parts ("pump method") often leads only to unnecessary waste and time loss. Follow the logical chain: Is there a spark? Is there fuel? Is there a compression? Is there a right moment to ignite?
Often the cause is a combination of small factors: a slightly weak battery, slightly contaminated contacts and a slightly over-enriched mixture. The car would start separately, but together these factors do not allow the engine to start. Therefore, always start by bringing the system to the ideal baseline state: clean contacts, fresh gasoline, normal battery charge.
If you have checked all systems but the result is negative, it is possible that the problem lies in rare malfunctions, such as a camshaft failure (cut the veneer) or a crack in the GBC. In such cases, without specialized equipment and removal of the head of the block can not do.
90% of the problems with the launch of the Moskvich 412 are solved by restoring a normal spark and cleaning the fuel system. Donβt look for complex causes until the simple ones are eliminated.
Why does the Moskvich 412 start and immediately die?
Most often, this indicates a malfunction of the idling system in the carburetor (a jammer is clogged or the electromagnetic valve does not hold fuel) or a strong sucking of excess air through the gasket of the intake manifold. It is also possible to stick the needle in the float chamber.
What to do if the spark is missing after washing the engine?
Moisture got into the trampler or the coil. It is necessary to thoroughly dry all elements of the ignition system with compressed air or a hairdryer (without overheating the plastic). Treat high-voltage wires and tramblor cover with a moisture-protective spray.
Can I start the engine from the pusher if the starter is not working?
Yes, the Moskvich 412 with a manual gearbox can be started from a pusher or on a cable. However, if the starter does not spin because of a jammed engine, pushing will only aggravate the situation. Make sure the engine is turned manually (with a ratchet) before trying to start by towing.
How often should I change the candles to Moskvich 412?
The resource of candles depends on the quality of fuel and the condition of the engine. On average, on the classic UZAM engine candles serve 15-20 thousand km. However, it is recommended to check and clean them every 5,000 km, especially if the car is used in an urban cycle.