The fan serves for increase in intensity of cooling of a radiator with air. The more intensively having blown, the more intensively heat exchange. Depending on model and a complete set on engines electric fans or fans from viskomufty are installed. Both types of fans are mounted just before a radiator and join as required.

Fig. 4.50. Viskomufta in a section: 1 – coupling case; 2 – case cover; 3 – press washer; 4 – reserve cavity; 5 – working cavity; 6 – pin; 7 – bearing; 8 – bearing axis; 9 – laying; 10 – bimetallic plates; 11 – valve

Viskomufta (fig. 4.50) filled with silicone oil is located in the middle of a krylchatka of the fan and copes bimetallic plates. On bimetallic plates there is a steel pin which at a surrounding temperature about +85 °C opens pass of oil to a working cavity. Viscous silicone oil creates power short circuit between a pulley and the fan under the influence of what the last begins to drive air.

At the cold motor the coupling is almost disconnected — oil is in a reserve cavity therefore there is no power consumption on ventilation. Speed of the fan remains lower than 1000 ^min.-1. It changes together with engine speed, but only at low turns. At achievement of 4500 ^min.-1 the safety valve which limits fan speed around 3300 ^min.-1 works.

SEQUENCE OF WORKS

1. On the switched-off engine check ease of the course of the fan.

2. Track that the fan had no strong axial and radial side plays.

3. Be convinced of absence on a viskomufta lack of traces of oil. If oil is, then it is subject to replacement.

4. On the heated-up motor and the closed cowl establish turns of 3000 ^min.-1.

Fig. 4.51. Viskomufta: 1 – krylchatka; 2 – coupling case; 3 – bolts of fastening of a krylchatka; 4 – bimetallic plates

5. Coupling (fig. 4.51) has to begin work at a temperature of cooling liquid of +90... +95 °C. Otherwise replace the coupling.

The electric fan is installed only on 4-cylinder engines. The cooling system of the 4-cylinder engine "is at once loaded" during the operation of the engine in the mode of idling or, for example, at the movement on the mountain area. If suddenly the control lamp of temperature of cooling liquid periodically begins to light up, then it speaks about malfunction of the fan. In this case you can continue the movement to the place of repair, previously having allowed the engine to cool down. At the same time the engine should not experience big strain and idle as little as possible.

PREVENTION At stopped, but still the hot engine do not hold a hand around a krylchatka of the fan! The fan can begin work and at the switched-off ignition.

SEQUENCE OF WORKS

1. Check a safety lock.

2. Disconnect the plug from the socket which is near the thermostat case.

3. Peremknite wire plug. If the fan starts working, so the thermoswitch is faulty. If does not earn — the fan is faulty or the cable has break.

4. For continuation of the movement you peremknit the plug and insulate it. Also, in order to avoid short circuit and hit of dirt, insulate a reciprocal part.

5. At a long stop or the parking surely remove a wire crossing point in order to avoid the category of the accumulator.