UMZ-421 engine: characteristics

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

The UMZ-421 engine and its modifications occupy a significant share in engine building. This unit became famous for being installed in a large number of cars of the UAZ company. In UMZ-421, amplifiers of the vacuum principle of operation are used. According to most, knots have a high pitch. And also tensioners have a large motor resource. For a more detailed analysis of the basis and modifications of the engine, it is proposed to familiarize yourself with its characteristics below.

General characteristics of UMZ-421

Model 421 has a four-cylinder block layout, in-line type. Piston diameter 100 mm. The compression in the cylinders is 8.2 bar. Maximum power is reached at 4000 rpm and is 221 ks per meter. Motor consumption varies depending on the model. The price of UMZ-421 is around 120 thousand rubles.

Motor structure

Version 421 (motor) includes cylinder block, carburettor and pump. Also useddamping device. The main shaft of the motor has a diameter of 24 mm. The pulley is installed with a cooler. Closer to the crankcase, this model has a fitting. The attachment point is located at the top of the assembly. The filter is located below the carburetor. Tensioners are a modified tank design.

Oil drainer

Oil drain in modification 421 (motor) is located on the side of the mechanism. The oil circulation valve is quite reliable, as it works at high pressure. Gases are removed by means of technical channels. A gasket is installed to prevent the block from being quickly worn out. The pulley at the bottom of the motor is protected from gases. To drain the used oil, a pipe without a filter is provided.

Connection assembly

Under the main drive is the choke assembly of the motor. It has a design of two shafts connected by a disk. This unit uses a low pressure valve. The outlet pipe is located below the carburetor. To serve the node, you need a rack. In the UAZ-421 modification, the hose is already installed in the crankcase. There are 3 filters installed throughout the system.

The tank is fixed with clips. The lower part in this modification has small holes. The upper pulley is also fastened with a clamp. A gasket is installed on the motor stand. At the top there is an air filter, below there is a connector block. There is a pulley under the tank. This is one of the features of the UMZ-421 ("Gazelle") model. Do not forget that they also include hoses for supplying the cooling system.

Motor starter

The motor starter of modification UMZ-421 hasclosing mechanism. It also has three blocks. Power supply to the starter is carried out through three contacts. A contactor is used to start the starter.

Cooling system

The entire cooling and coolant recirculation system is connected to the starter. A connector is installed under the 421 motor block. The pulley has a diameter of 3 mm. One pipe comes out of the tank. When parsing the upper part of the cooling system, it is worth mentioning the separate channels for venting gases. Mounting devices are installed with nuts. Dismantling is only possible with box or open-end wrenches. The shaft must be immobilized during dismantling. After removing the pump, it will be possible to remove and inspect the starter.

Model 421.10

Model 421 (motor) has the characteristics: at the peak torque will be 221 ks per meter, the average number of revolutions is 2500 per minute. This model has an elongated pin. The carburetor is mounted with a drive. Valve installed with tensioner.

It is worth mentioning that the unit has a wide output. The UAZ-421 motor model has a tensioner with a pipe. All channels are equipped with special overlays. One of the features of this model is a modified starter. The filter is located in the front part of the damper. One of the disadvantages is poorly secured hoses on the carburetor. The second common problem can occur with the connector. In turn, it is attached under the drive. The design of the fan is designed to work for a long time on largerpm.

Motor 4215.10

Model 421 is produced with a modified crankcase, it has cooling. The shaft is mounted on two drives. One of the distinctive qualities of this model is resistance to increased overloads. The oil system has a successful design, it is made of sufficient quality. In view of the above, even oil drain pipes rarely cause pollution problems. Many experienced users and mechanics will note the successful design, shape and size of the channels. Based on this, the oil does not coke. The carburetor has the now familiar post-mounted design, and the connector is on the bottom.

Motor model 4218.10

This 421 motor is made with reinforced gaskets. The cylinders are located on different sides. The advantages of the modification are elongated channels. The crankcase has better protection compared to its predecessors. Mechanics and experienced users also note a much more comfortable neck size. The motor has three pulleys. In the modified cooling system, the radiator is installed with additional racks. Also, due to the heat load of the motor, the fan is designed for high speeds. The pump of this motor is used with a connector. The air inlet filters are located at the cross member. The tensioners are on the bottom. The shaft is fixed with nuts. To service the motor, you first need to remove the cooling system. The next step is to fasten the pulley to the top of the motor and unscrew the bolt. It has a right hand thread. Using the keys, removemotor expander. The gasket is relatively thin.

Starter Service

Most often, this motor has problems with the starter due to souring or disconnection of contacts. To find out the problem, it is necessary, using the keys, to disconnect the block connecting this node. Next, inspect the outer and inner surface of the part for oil streaks. Perhaps the problem is not leaking from the tank, but from the hose. One of the "diseases" of this part is displacement from the seat. When offset, the nozzle is pinched.

The last step is not to forget to inspect the supply. To remove the starter you will need a "+" type screwdriver. In this version, the fittings do not need to be removed. You will also need a screwdriver to remove the hoses. The top starter bolt is located near the reservoir. It is not necessary to remove the pipes in this embodiment. Once the bolts are out, the starter can be easily removed without the aid of any other tools. One of the problems with starters installed on this unit is poorly fitting contacts to the clamping bars. To fix the problem, this can be done manually by simply pressing them.

Connector Maintenance

Maintenance of the connector gasket is a fairly simple task. When leaks appear, the first step is to wash the engine. Once the workplanes are cleared, verify that the connector is the culprit. To repair a motor with index 421, you need to inspect the part itself. It is also worth paying attention to the tank parts, and do not forget to dismantle the pulley from the top of the motor. Todiagnose the tank, you will need the keys.

As with other motors, the screws are located on the sides of the cover. The cover should be dismantled slowly and carefully. The gasket must be in its seat. It is worth mentioning that during installation, the tank should also be held. Better get help. The gasket should not be too hard and dirty. If the color of the surface is uneven, it is worth replacing it with a new one. After replacing the gasket, everything is assembled in the reverse order. The bolts should be tightened gradually, with a uniform force. During assembly, it is worth monitoring the position of the gasket, if it stands up unevenly or sticks out, the procedure will have to be repeated again.