KAMAZ 740 engine: device and repair

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

KAMAZ trucks began to be built in 1969. For a new generation of trucks, engineers have created a 4-stroke eight-cylinder diesel engine KAMAZ-740 V8. This power unit had a working volume of 10852 cm3, and its power was 210 horsepower. Then the power figures had to be expanded from 180 hp. up to 360. These trucks were equipped with a pneumatic clutch booster, a 5-speed gearbox with synchronizers.

Diesel unit device

The design of these engines, when compared with others running on diesel fuel, has some advantages. The unit has relatively small dimensions, and also has a lower mass in comparison with the same YaMZ 238.

The torque from the motor to the main components is transmitted through spur gears. So, the drives of the gas distribution system, pumps and compressors, as well as the hydraulic booster work on the gears.

This engine (KamAZ 740) has a good start even at very low ambient temperatures. This was made possible by the power of the battery, starter and pre-start heater.

Engine specifications

The model of power plants was named - diesel KamAZ 740. The cylinders are arranged in a V-shape. The crankshaft rotates to the right. The cylinders are 120 mm in size and 120 mm deep. Engine KAMAZ 740 with a displacement of 10.85 liters. it has a high compression ratio - 17. Power according to the passport in kW ranges from 154 to 210. Maximum torque - 650 kgf / m. The minimum fuel consumption is 165 liters, the maximum - 178 liters. Each cylinder has one intake valve and, accordingly, one exhaust valve.

Let's consider the KamAZ 740 engine, the device of various components and systems.

Cylinder block

This assembly is nothing more than a part of the unit body. It is intended for mounting and securing all mechanisms and basic systems. The cylinder block is made in the form of a monolithic cast structure. The part has technological holes, as well as channels for lubrication and cooling.

In the upper part of this block there are sockets for cartridge cases. Also, the body is equipped with channels and cavities for the passage of coolant. The lower part of the cylinder block also serves as the crankcase. Here is the crankshaft. The crankcase has two technological holes for lubrication. Inside the node has partitions with special stiffening ribs. In thesepartitions and walls of the crankcase are made with special bores that are closed with covers. These parts serve as supports for the crankshaft.

The block is equipped with supports for the camshaft, as well as pushers for the gas distribution mechanism.

Liners serve as piston guides. Together with the block head, they form a special cavity, which is a fuel combustion chamber. The sleeves are made from special cast iron and are also electrically hardened.

The upper part of the plane is represented by cylinder heads. Each one with its own head. These parts are made of aluminium. Each head has a cooling jacket inside, which in turn is connected to the block jacket. Also, each head has lubrication holes, valves for inlet and outlet, a special socket for the nozzle.

Design and operation of the lubrication system

The KAMAZ 740 engine is equipped with a combined type lubrication system. Depending on where the rubbing parts are located and under what conditions, oil is supplied in various ways. The system can spray, supply oil at low pressure, or let it flow by gravity.

The device supplies oil under pressure to parts that are more subject to wear and work in especially loaded nodes. This unit consists of the main instruments and devices in which lubricant is stored, filtering and supply devices, as well as oil cooling.

Oil passes from the sump to the oil receiver, passes throughspecial filter in the form of a grid. Then it goes to the oil pump. From the discharge section, through a special channel, the lubricant is supplied to the oil filter, and then to the mains. Further, the pressure lubrication channels lubricate the cylinder head and cylinder block, and then to other components such as the crankshaft, gas distribution mechanism, compressor and fuel pump.

In the cylinders, excess grease is removed using oil scraper rings, and then goes further through the piston grooves. This lubricates the piston pin bearing in the top head.

From the main line, oil is supplied to the thermal force sensor. If a valve is opened that includes a fluid coupling, then the coupling is also processed. If it is in the closed position, then liquid is supplied from the centrifugal filters to the sump.

If there is not enough lubrication, then power drops, and parts suffer increased wear, the motor overheats, the bearings melt, and the pistons can jam.

KAMAZ 740 engine power system

This is not the end of our review. We examined the KamAZ 740 engine itself, the device and the lubrication system. Now let's get acquainted with the power scheme.

Power units are designed to store fuel, clean it, and then spray it into the combustion chambers in accordance with the operating mode of the power unit.

The KAMAZ 740 engine is equipped with a separation type power unit. Here the injection pump and injectors are separated. The system consists of diesel fuel storage tanks, fuel filters, low pressure pump, injection pump,as well as fuel lines.

How does it work?

From the fuel tanks, the fuel passes through the booster pump to the cleaning filters. Then, through the network of low-pressure fuel lines, diesel fuel is supplied to the high-pressure fuel pump. After the injection pump, it pumps diesel under high pressure in portions, based on the engine operating modes, through the nozzles into the cylinders and combustion chambers. The nozzles, in turn, spray the mixture. Excess diesel gets back into the tank through the bypass valve.

KAMAZ 740 engine cooling system

Cooling is presented as a closed system with liquid coolant and forced circulation.

In principle, the scheme of operation of this system is no different from the usual for all car brands. If there is a diagram of the KamAZ 740 engine, then you can see it in more detail.

The coolant circulates under the influence of a centrifugal pump. First, antifreeze enters the cavity of the left row of cylinders, then through the tube - into the right cavity. Then the mixture washes the cylinder liners, and then through the holes - the cylinder head cavity.

The hot coolant then enters the thermostats and then either the radiator or the water pump. Temperature conditions are regulated by thermostats and fluid couplings.

Major engine failures

Among the owners of this car, the main malfunctions of KamAZ 740 engines are considered to be a sharp decrease and power surges, an increase in the consumption of lubricants and fuel. Also a popular malfunction is high exhaust smoke. Notrarity and pressure drop in the lubrication system.

The unit may be unstable at idle, sometimes there are different extraneous sounds in various nodes. Basically, malfunctions are associated with the crankshaft. Possible coolant leak.

If the unit was used to the limit, and more often - if the KamAZ 740 engine did not have proper maintenance, repairs are inevitable. But after a major overhaul, the machine will be able to work again at full capacity, and perhaps even much better.

About prices

Today, such a unit can still be purchased. For the KamAZ 740 engine, the price will be, depending on the configuration and power, from 550,000 rubles for a model with a power of 240 hp. With. up to 600,000 rubles for a model with a capacity of 320 liters. With. Of course, you can buy and much cheaper. The market for used motors today offers a lot of options at lower prices.

So, we found out all the features of the "KAMAZ" engine.