The engine cooling system is liquid-cooled, closed type, with forced circulation of coolant.
The main elements of the cooling system are: water pump, radiator with a shutter, thermostats, fan, fan drive fluid coupling, fluid coupling switch, expansion tank, connecting pipelines.
The water pump, thermostats with thermostat housing, fan, fan drive fluid coupling, and fluid coupling switch are mounted on the front of the engine.
The water pump is secured with bolts to the left front part of the cylinder block.
To provide access for removing the water pump and fan drive fluid coupling, remove the radiator grille, water radiator, and oil radiator.
The water pump should only be disassembled if the impeller seal is worn or damaged, or if the bearings are worn. Coolant leakage from the pump drain hole indicates wear or damage to the impeller seal.
To disassemble the water pump (Fig. 2), press the pulley 3 off the shaft 10, remove the key 1 and dust deflector 2;
Remove the retaining ring 4, remove the cotter pin and unscrew the nut 11, remove the impeller 8, sealing ring 9 and thrust ring 13;
Press the shaft 10 with bearings 5 and 6 out of the housing 7, use mandrels to press out the water deflector 15 and water pump seal, press the bearings 5 and 6 off the shaft 10.
Assemble the water pump in the reverse order of disassembly (12 — lock washer, 14 — seal).
The fan drive fluid coupling (Fig. 3) and the fan are secured with bolts to the front of the cylinder block.
When the friction surfaces of the seal 28 and cover 27 wear out, oil leakage will occur, and the fluid coupling will not work, i.e., it will not transmit rotation to the fan.
To eliminate this malfunction, remove the fluid coupling from the engine.
On the removed fluid coupling, unscrew the nuts 30, carefully remove the cover 27, and replace or repair the worn parts.
During complete disassembly of the fluid coupling, remove the cotter pin and unscrew the nut 9, remove the washer and press off the hub 10.
Unscrew the bolts 12, carefully separate the pulley 17 with the seal 7 from the shaft 14 without damaging the gasket.
Remove the pulley, gasket 13 and bush 11. Unscrew the nuts 30, carefully remove the cover 27, gasket 31, seal 28 and spring 26. Remove the thrust rings 23 and 29.
Unscrew the nuts 2, carefully rocking the body 18, remove the fluid coupling from the bracket body 19.
Unscrew the bolts 33 and separate the driven wheel 32 with the shaft 8 and casing 20 from the driving wheel 3.
Remove the body 18 from the bearing 16. Use a mandrel to press the bearing 6 out of the shaft 14, remove the thrust ring 5.
In case of extreme necessity (breakage of bearing 16 or wheel 3), unscrew the bolts 4, remove the washers, press the driving wheel 3 and bearing 16 off the shaft 14.
Press the bearing 24 off the driving shaft 22. Use a mandrel to press the driven shaft 8 with bearing 25 out of the driving shaft 22. Press the bearing 25 off the shaft 8.
In case of extreme necessity, unscrew the bolts 21 and press the shaft 8 out of the driven wheel 32. If the casing 20 or driving shaft 22 fails, replace them with new ones as an assembly.
Assemble the coupling in the reverse order of disassembly. Observe the following requirements.
Before pressing the wheel 3 onto the shaft 14 and the wheel 32 onto the shaft 8, the wheels must be heated in an oil bath to 100 °C.
After assembling the fluid coupling, check the rotation of shafts 14 and 8.
When pressing the hub 10 onto the shaft 8, use the M8 threaded hole in the front end of the shaft.
Pressing the hub onto the shaft with a hammer is unacceptable, as the bearings may be damaged.
When rotating by the pulley 17, the shaft 14 should rotate freely, without binding. When the pulley 17 is stationary, the fan hub 10 with the shaft 8 should rotate freely, without binding.
Lubricate the seals 7 and 15 with CIATIM-201 lubricant before installation.
Lubricate the gaskets 1, 13 and 31 with consistent lubricant before installation (34 — gasket, 35 — nut, 36 — drain pipe).
The tensioning device (Fig. 4) is used to adjust the tension of the fluid coupling drive belts from the crankshaft pulley.
To remove the tensioning device, unscrew the nuts of the two studs securing the tensioning device to the fluid coupling bracket body.
If the pulley bearings are to be replaced, remove the front spring ring 6, cover 5 and locking ring 4.
Remove the pulley 2 with bearings 3 from the pin 8.
Remove the rear spring ring 6 and press the bearings out of the pulley.
The pin 8 is only pressed out of the lever 1 in case of extreme necessity.
Assemble the tensioning device in the reverse order of disassembly (7 — spacer ring).
The fluid coupling switch (Fig. 5) is installed on the front of the engine on the pipe supplying coolant to the right row of cylinders.
On Ural vehicles, the switch is remotely controlled via the rod 4.
In spring, during seasonal vehicle maintenance, check the actuation temperature of the fluid coupling switch in automatic mode (lever 13 set to position B) under bench conditions.
If necessary, adjust the actuation temperature of the switch by changing the thickness of the adjusting shim pack 17.
To check the operation of the switch in automatic mode, remove it from the engine.
Supply a pipeline with engine oil at a pressure of 7 kgf/cm2 to channel «D», and immerse the nut 18 and sensor 19 in a vessel with heated water.
Measure the water temperature in the vessel near the sensor with a mercury thermometer with a scale division of 1 °C. Heat the water in the vessel while constantly stirring.
The switch is correctly adjusted if it actuates at a water temperature of 85-90 °C — oil flows from channel «C».
If the switch actuates at a temperature above 85-90 °C, reduce the thickness of the adjusting shim pack 17.
If the actuation temperature cannot be adjusted with the shims, replace the sensor.
In case of complete disassembly, unscrew the bolts 2, remove the cover 3, spring 7, washer 6 and remove the spool 8 from the housing 5.
Unscrew the bolts 1, remove the cover 16 with the plug 11 and lever 13.
Unscrew the nut 18, remove the sensor 19 and adjusting shims 17. If necessary, drive out the pin 12 and separate the plug 11 from the cover 16 and lever 13, remove the spring 14 and retainer 15 (9 and 10 — sealing rings).
The thermostats (Fig. 6) are installed in the thermostat housing, located on the fan drive fluid coupling bracket body.
To remove the thermostats, unscrew the bolts and remove the thermostat housing cover.
For the thermostats, the valve 10 opening start temperature and the total travel amount are monitored.
The thermostat test diagram is shown in Fig. 7. After heating the water to 70 °C, continue heating while constantly stirring.
The temperature at which the valve travel is 0.1 mm is taken as the valve opening start.
The valve should begin to open at a temperature of 78-82 °C, and fully open at 90-95 °C. The full valve travel is 6.8-8.5 mm.
The radiator with fan cowl, frame and oil radiator are mounted on the first cross member of the frame.
The main radiator malfunctions may be: external contamination of the core, damage to the tubes, dents and cracks on the walls of the lower and upper tanks, breakage and cracks of the branch pipes.
If water is used as coolant, scale may form.
Before repair to locate the leak and after repair to check for leaks, test the radiator with air at a pressure of 1.0-1.2 kgf/cm2 by immersing it in a water bath.
To clean the external surface of the core from contamination, wash it with a hot alkaline solution.
Solder damaged external tubes with soft solder without disassembling the radiator. Internal tubes (inaccessible for soldering) can be plugged.
The number of plugged tubes must not exceed 5% of the total number of core tubes.
If there is a large number of damaged tubes, or to repair the attachment of the branch pipes to the tanks, open (unsolder) the upper and lower tanks and replace the tubes with new ones.
Straighten dents in the tank walls, solder cracks by applying patches made of brass sheet 1.0-1.2 mm thick.
If water is used as coolant, in spring during seasonal maintenance, flush the cooling system to remove scale.
To do this, fill the system with water adding technical Trilon B at the rate of 20 g per litre of water.
After one day of vehicle operation, drain the solution. By adding fresh solution daily, flush the system for 4-5 days.
If using the low-freezing coolant Tosola-A, dilute it with soft clean water in a proportion depending on the ambient temperature in winter.
