But when the engine is cold, such as in winter, the temperature of the compressed air does not reach the ignition temperature of the fuel.
Left front side (looking in the direction of travel) cylinder heads are located: 1 - temperature indicator sensor; 2 - oil pressure sensor; 3 - engine temperature sensor for pre-glow system
Cold start with glow plug
To start a cold engine, it is necessary to increase the temperature of the air in the cylinders.
For this, glow plug tubes are used in the vortex chambers of the cylinders. The glow tubes are heated by current from the battery. Thus, the air in the vortex chambers is additionally heated.
Various options
in diesel models "Golf", released in different years, there are two different wiring diagrams for the pre-incandescence installation. Starter and glow switch (winter ignition) has the following external features:
- Until July 1977, the starter switch lock had an additional position "Vorgluhen" ("Pre-glow"). The ignition key remained in its position until then. until the pre-glow indicator lamp goes out. Then start-up takes place.
- After August 1977, this additional key position is no longer there. An updated starter and glow switch matched the ignition lock of carbureted models..The wiring diagram of the pre-glow system has also been changed.
- After August 1980 there was a further improvement of the fast glow system (previous wiring diagram). The incandescent system differs from the previous variants in that it has a different pre-glow relay and other glow plugs, which reach the required temperature much faster.
Wiring diagram used after August 1977
On this wiring diagram preheating systems.
In the current line 19-22 there are four glow plugs. They are not switched on one after another in series, as is done by some manufacturers; each individual glow plug receives full voltage (parallel connection). Current line 19 on newer models has a 50A plate fuse. It is located in a black box at the rear bulkhead in the engine compartment.
Electric current flows from terminal 30 through the contact of the pre-glow relay. inside the relay (J52 on wiring diagram) there is an electronic circuit; the transistor designation indicates this. This circuit receives from the engine temperature sensor (current line 17) information about the current temperature of the engine. When the starter switch is in its first position, the electronic control extinguishes the pre-glow indicator after a certain time. The time interval before the light bulb goes out (that is, during the period when pre-heating is carried out) determined depending on the engine temperature At an engine temperature of 0 degrees Celsius, the additional glow time is 25 seconds. in a conventional incandescent system and 7 sec. in the fast heating system.
After the pre-glow indicator lamp goes out, the so-called post-glow period begins. It is 15 sec. in a normal system and 6-7 sec. in the fast heating system.
As soon as the starter switch is turned further, the starter drives the engine. Glow plugs during this period also receive an electric current. If you turn on the starter by releasing the key, the glowing process is also interrupted, regardless of whether the additional glow is completed or not. To electronic circuit "knew", when it needs to finish the extra glow after the starter is turned off, the relay is connected to terminal 50 of the starter and glow switch.
Wiring diagram used until July 1977
In diesel model "Golf" of the first constructive series, preliminary glowing is carried out in a similar way. True, there is no additional automatic incandescence. For this reason, the glow plug relay does not have a connection for terminal 50.
When the ignition key is held in the glow position, the glow plugs are energized because at the same time the switching contact of the pre-glow relay releases the current flow. From the engine temperature sensor, the relay electronics receive information about the temperature, on which it depends when the control lamp is extinguished.
In the process of starting the engine, the candles continue to glow further. Only after the starter is turned off are they without electric current.
Starter and glow switch
In models "Golf" two types of starter and glow switches were installed (egnition lock).
Until July 1977, the switch had 4 switching positions: "Aus" ("Off"), "Fahren" ("On"), "Vorgluhen" ("Pre-glow"), "Anlassen" ("Start").
Subsequently, a switch was installed in which the positions "On" And "Pre-glow" merged into one.
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