YaMZ-238 cooling system: possible malfunctions

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:41

Powerful turbocharged YaMZ-238 engines are designed for MAZ-54322 and MAZ-64227 vehicles. The demand and popularity of such diesel power units is explained by their high reliability and good technical characteristics. These engines have eight cylinders. They have an increased working resource, compared with competitors, by 15 percent. The engine starts without problems in almost any, even in the most frosty weather.

Motor design

The cylinder blocks of the YaMZ-238 diesel engine are made of gray cast iron. The cylinder liners are also made of a special carbide material. The power unit has two heads (one in each row of cylinders). Also inside the motor housing, the designers placed a forged crankshaft together with counterweights and supports. All eight engine pistons are made of aluminum alloy. Each of them has three compression rings and two oil scraper rings. Retaining rings are needed to limit the movement of the floating piston pins. also inThe cylinder block has forged steel connecting rods with an oblique connector on the lower head. To start the engine, a starter is used, in the body of which there is a flywheel with a ring gear.

Clutch

The shift mechanism consists of four forged pull levers that are mounted on needle bearings. Between the levers, the ratio goes 1 to 5, 4. Also in the design there are 28 pressure springs in the form of cylinders. They are made from steel wire. The cast iron middle drive plate is connected to the flywheel by large spikes that are located on the surface of the part.

Motor lubrication system

The diesel engine lubrication system of the Yaroslavl plant operates in mixed mode. Its main element is an oil cooler, which is installed next to the engine housing. This system also includes two filter elements:

1. Full flow oil filter with replaceable filter element.
2. Fine oil filter, powered by centrifugal force. It is equipped with a jet drive.

At the same time, the manufacturer allows the installation of a coarse filter instead of a full-flow one. High pressure lubricant is delivered to:

• crankshaft connecting rod and main bearings;
• camshaft bearings;
• connecting rod bushings;
• pusher bushings;
• rod supports;
• oil pump bushing;
• valve rocker bushing.

Grease forfuel pump and speed controller comes from the engine lubrication system. Gears, camshaft cams and rolling bearings are lubricated by spraying lubricant. In this case, the following pressure is created in the oil system during engine operation:

• At nominal speed - from 400 to 700 kPa.
• At rated speed during idling - not less than 100 kPa.

Cooling system elements

The cooling system in the YaMZ-238 (photo is attached to the article) is liquid, circulating. It includes a number of basic elements such as:

• fluid transfer pump;
• heat exchanger;
• several thermostats that regulate the flow of cooling to the cylinders;
• fan that supplies air to the cab and engine.

The YaMZ-238 engine has a turbo cooling system (a photo of the power unit is in the article) consists of the following components:

1. A pump designed to circulate water continuously.
2. The cavity where the sleeve cooling unit is located.
3. Water cavity in the block head.
4. Channel for the passage of water.
5. Compressor.
6. Right cooling tube.
7. Connecting tube.
8. Inlet pipe.
9. Thermostat.
10. Tee with tubes.
11. Bypass tube.
12. Stub.
13. Oil heat exchanger hose.
14. Fan.
15. Water channel located transversely.
16. The supply of liquid used to cool the engine from the radiator to the stove in the cab, to the air exhaust system, to the radiator.
17. Charge air supply system for cooler and radiator.
18. System for moving cooling air from the cooler to the engine cylinders.

In addition to the above, the cooling system of the YaMZ-238 unit consists of a radiator, charge air cooler, and a thermometer. All this equipment is installed on the vehicle.

Cooling principle

During normal operation of the YaMZ-238 motor from MAZ, fluid circulation in the cooling system is created by the operation of a centrifugal pump. The pump pumps the coolant into the transverse channel, and then it passes through the longitudinal channel and enters the water cavity of the cylinders located in the right row. Coolant enters the remaining cylinders of the engine through the inlet pipe. Thus, it is possible to cool the oil in two elements of the power unit at once.

Next, the antifreeze enters the left longitudinal channel. To allow coolant to enter the oil-to-liquid heat exchanger, the engineers pressed a plug into the front cover of the distribution gears. Then the antifreeze enters the cylinder heads through the tubes, cooling the most heated surface, such as exhaust channels, nozzle cups. The liquid is then drained into several drainage pipes. During warm-up of a freshly started engine, the cooling system does not function.

The thermostat valves prevent the movement of antifreeze. The fluid that serves to cool the engine from overheating circulates through the connecting pipes, the bypass pipe through the water pump. At the same time, it does not enter the radiator, due to which the power unit heats up to operating temperature. After the antifreeze heats up to 80 degrees Celsius, the thermostat valves open. The liquid heated to the required temperature enters the cavities of the water radiator, where it heats the air flow due to the operation of the fan. The antifreeze then flows back to the water pump.

When the temperature of the coolant drops, the thermostats direct it to the pump, bypassing the radiator. Thus, thanks to the thermostat locks in the engine, optimal thermal conditions are ensured.

Water pump

In the cooling system of KAMAZ with YaMZ-238, a water pump (this device is also called a "pump") is placed on the front wall of the cylinder block. It is rotated by a pulley belt that is mounted on the end of the crankshaft. The pump in the YaMZ-238 cooling system for MAZ-54322 and MAZ-64227 vehicles consists of the following parts:

• drive pulley;
• retaining ring;
• multiple bearings;
• roller;
• water ejector;
• mechanical seals;
• pump body;
• o-rings;
• pipe attached to the water pump;
• impeller;
• cap for impeller;
• sleeveto O-ring;
• drainage hole.

Pump principle

The cooling system in the YaMZ-238 turbo works due to its main element - a pump (water pump). Inside its body, made of cast iron, an impeller rotates, which is pressed onto a roller. This creates an airflow.

To ensure the rotation of the roller in the YaMZ-238 cooling system, it is mounted on two ball bearings. The bearing cavities are tightly clogged with lubricant (lithol), which is designed for the entire life of the pump. This material does not need to be replaced.

To ensure a tight mechanical seal in the pump body, a drain hole has been made. The drive pulley is pressed onto the roller.

Each water pump, due to which the cooling system in YaMZ-238 works, is marked with a digital and letter designation.

Water pump function

The main task of the water pump in the cooling system in YaMZ-238 is to ensure the circulation of the cooling liquid. It must also maintain a certain speed of movement of antifreeze. A running engine must "give" a certain amount of heat to the cooling system. Then the heated liquid is cooled in the radiator fins.

Heavy loading on a cold engine is just as dangerous as overheating the power mechanism.

Selecting an engine pump

For the operation of the oil cooling system in the YaMZ-238,various water pumps, but the product under the YaMZ-236/238 marking turned out to be the most reliable. Its parameters are ideal for the operation of powerful power units with the same letter and number index.

Such a pump is capable of distilling liquid through the cooling system at a speed of about 30 liters per minute with a shaft torque of 0.52 units. The weight of such a product does not exceed 9 kg. Pump dimensions may vary depending on the type and power of the engine for which it is intended.

In addition to the dimensions, the pumps for the normal operation of the oil cooling system in YaMZ-238 may differ in connecting dimensions.

Antifreeze or antifreeze is used as a coolant in the system. This means that the pump must operate at an ambient temperature of -40 to +50 degrees Celsius and withstand the same temperature of the coolant that it drives through the system. Also, the pump in the YaMZ-238 cooling system, with a volume of 11150 cubic centimeters, should work properly if water is poured into it, which heats up to 100 degrees Celsius while moving through the nozzles through the radiator and engine housing.

Checking the cooling system

During periodic vehicle inspections, mechanics need to pay special attention to the condition of the YaMZ-238 cooling system with a volume of 11,150 cubic centimeters. It is necessary to check the tightness of the pipes and joints in order to prevent leakage of antifreeze in time.

To check the engine cooling pump fortightness, it is necessary to increase the pressure in the power unit to 3 kgf/cm2and hold it for one minute. You can also test your pump for leaks by running compressed air through the system for 30 seconds.

If the system is tight, the specialist needs to check the operation of the mechanisms. To do this, turn the pump shaft. It should rotate freely along its axis.

Water pump removal

Many mechanics are interested in what possible malfunctions in the YaMZ-238 cooling system may occur during the operation of the car? The most common cause of a violation of the heat exchange of the motor and antifreeze is a breakdown of the pump, which overtakes the coolant. In the event of a malfunction of such a part, it is necessary to find the cause of the breakdown by disassembling it. Then you need to decide on the advisability of repairing the device or proceed with its complete replacement. To disassemble the water pump, the master needs:

1. Loosen the pump drive belt and then remove the belt from the pulley.
2. After that, you need to drain all the liquid from the system, including the engine and radiator.
3. Then you should dismantle the pipe attached directly to the pump.
4. The last operation to dismantle the pump is to remove the pump from the engine. To do this, unscrew the fastening of the pump housing.

Pump disassembly

To disassemble the YaMZ brand water pump for further repairs, you need:

1. Unscrew the nuts that hold the nozzle.
2. Remove the nozzle frompump.
3. Lock the pulley to prevent the shaft from rotating.
4. Remove the plug by turning it out of the threaded hole.
5. Wrap the puller nut into the pulley hole, and then, screwing the bolt, remove the pulley from the shaft.
6. Unbend the guides of the mechanical seal housing, and then remove the lip with spring and frame assembly.
7. Compress the pulley with a special puller.
8. Pull the circlip out of the pump groove.
9. Remove the shaft together with the bleeder and bearings from the pump housing.
10. In the event that the body of the mechanical seal, made of brass, has no visible damage, then it can not be pulled out. Otherwise, it must be removed and replaced with a new one.
11. This completes the disassembly of the pump.

Reassembly after repair

After the pump is completely disassembled, the malfunction is identified, all damaged elements are replaced with new ones, all serviceable parts should be washed and then dried thoroughly. Compressed air can be used for this.

Next, you need to assemble the product for its further installation on the car engine. To do this, you need to perform a number of operations:

1. Press the bearings and the water deflector onto the shaft. In this case, the shaft should be lubricated with oil for diesel engines. The bearings must be installed in such a way that the sealing washers are on the outside. All pressing force must be applied only to the inner ring of the bearings.
2. Next, you need to fill opencavities between the bearings, formed after pressing, with a special grease "Litol-24.
3. Lubricate the shaft with previously unused engine oil.
4. During the following operation, the shaft assembly must be installed in the water pump housing. A fixed stop must be provided on the opposite side of the shaft.
5. Next, you need to install the mechanical seal from the brass body.
6. Install a rubber cuff assembly with a spring and several frames.
7. Next, put the cuff on the sealing sleeve.
8. Then it is necessary to lubricate the pulley bore with a thin layer, as well as the outer surface of the cuff, which is made of rubber.
9. Install reinforced lip and seal bushing.
10. Mount the pulley in the rubber cuff and bushing for sealing. To avoid various distortions and the occurrence of gases in the YaMZ-238 cooling system, grasp the cuff with both hands and then insert it into the pulley bore.
11. Next, you need to press the pump pulley assembly onto the shaft, but before that, remember to lubricate both parts at the contact points with previously unused engine oil.
12. Lock the pulley to prevent it from rotating.
13. Tighten the cap tightly.
14. Mount the rubber ring and bushing into the water pump housing.
15. Put the ring into the groove of the pipes.
16. Connect the pipes of the YaMZ-238 cooling system to the pump.
17. Fix the nozzles with hardware.

This completes the water pump assembly.