4.4. System of preliminary warming up of the diesel engine

At launch of the cold engine temperature of spontaneous ignition is not reached only due to compression therefore preliminary heating of fuel-air mix is necessary.
For this purpose the glow plug is screwed in each combustion chamber. It consists of the case with the heating core pressed in it. When giving tension the heater winding in a core within several seconds is warmed up to the temperature over 850 °C therefore heating duration before start-up seldom lasts more than 10 pages. At switching off it is possible to launch the engine in combinations of devices of a control lamp of preliminary warming up.
For acceleration of warming up of the engine on models since 1987 of release preliminary heating continues also after its start-up. Duration of heating is defined by the control unit depending on temperature of cooling liquid. The control unit is behind the central console under an air duct. Information on temperature of the engine comes to the control unit from the sensor of temperature of cooling liquid. On the basis of the obtained data the control unit determines duration and current.

Check of system of preliminary heating of the engine
At the difficulties arising at launch of the engine first of all measure a compression in engine cylinders. If compressions it is too small, then at low ambient temperature the engine will not be launched.
Check of candles of an incandescence
Turn off nuts and disconnect wires from incandescence candles.

Fig. 4.17. Use of an ohmmeter for measurement of resistance between contact of a glow plug and the block of cylinders


Connect consistently to each glow plug an ohmmeter and check resistance between contact of a glow plug and the block of cylinders (fig. 4.17).
If resistance is not equal to zero, the glow plug is faulty and it needs to be replaced.

Fig. 4.18. Glow plug: 1 – a nut with washers; 2 – connecting wire; 3 – candle


Turn out a faulty glow plug. Screw new svechunakalivaniye and tighten its moment 20 N • m (fig. 4.18).
Connect a wire to a glow plug and fix it by a nut with washers.

PREVENTION
Do not exceed the specified inhaling moment as the core of an incandescence can be damaged and a candle will prematurely fail. You watch that on a glow plug oil or fuel did not get.

Glow plugs with the burned heating cores.

Fig. 4.19. A glow plug with the burned core


Obgoraniye of cores of candles of an incandescence (fig. 4.19) often is a consequence of malfunction of fuel nozzles. Similar damages should not be ranked as internal or external defects of a glow plug.

PREVENTION
If damage on is revealed, and the engine is launched badly, perform external inspection of candles of an incandescence at the included preliminary heating. For this purpose remove fuel nozzles and through openings watch glow plugs at warming up.

At detection of similar candles of an incandescence it is not enough to replace of them. In this case it is also necessary to carry out an inspection of fuel nozzles on pressure of injection and tightness.
Check of the relay of candles of an incandescence

Fig. 4.20. Connection of the relay of candles of an incandescence to plugs of the rechargeable battery and check of short circuit of contacts of the relay


Disconnect the contact socket of the relay of candles of an incandescence. Two additional wires connect the relay to plugs of the rechargeable battery, as shown in fig. 4.20, and check whether contacts of the relay become isolated.
If contacts of the relay do not become isolated, replace the relay.