Engine overheating
The coolant temperature gauge needle is in the red zone at the end of the scale.
Causes of the malfunction and ways to eliminate it:
- no coolant or low level of coolant. Fill the expansion tank with coolant and check the system for leaks;
- the outer surface of the radiator is heavily contaminated. Clean the outer surface of the radiator with a jet of water under low pressure;
- the thermostat is faulty. Check the thermostat operation, replace if necessary;
- failure to turn on the electric fan. Check the coolant temperature at which the contacts of the electric fan switch are closed. Switching on should be at 96...102°C. Replace the faulty switch sensor or electric fan with a new one.
Engine overcooling
The coolant temperature gauge needle shows less than 85°C.
Cause of the malfunction and how to fix it:
- thermostat is faulty (the main valve is constantly open, the liquid circulates constantly in a large circle). Check the operation of the thermostat, replace if necessary.
Coolant leak
Frequent topping up of fluid in the system.
Causes of the malfunction and ways to eliminate it:
- damage to radiator tubes. Repair the radiator by installing smaller diameter repair tubes and then mandrel-fitting them (by pressing with a mandrel);
- loosening of the screw clamps securing the hoses. Tighten the screws, replace if necessary;
- damage to the coolant pump seal. Replace the seal, which requires disassembling the pump. To remove the pump, you need to hang up and partially disassemble the engine. With the pump removed, use a puller to press off the toothed pulley 9 (see figure 32) of the pump, unscrew the locking screw 1 and press out the shaft 5 together with the impeller 4, bearing 8 and seal. Remove the seal. If necessary, press off the impeller. When assembling the pump, use a mandrel to install a new seal into the pump casing without distortions. Press in the shaft with the bearing so that the seat of the locking screw 1 coincides with the hole in the pump casing. Tighten the locking screw of the bearing and calk the contours of the seat to prevent the screw from loosening. Then, using a device, press on the impeller 4 and toothed pulley 9, maintaining the dimensions indicated on figure 32. Before pressing the pulley, heat it up to 150...200°C.