Glow plug for diesel. Glow Plug Relay
The design of diesel engines is slightly different from traditional gasoline. Among the differences in design, there is a different principle of ignition of the air-fuel mixture. If in gasoline units the mixture ignites from a spark, then in diesel units it is not like that. Let's get acquainted with the design and purpose of glow plugs in diesel engines.
Assigning candles in a diesel engine
So, the glow plug first of all heats the air in the cylinders before the start. So, to start the diesel unit, if the temperature on the street below 5 degrees above zero, is almost impossible. These parts greatly increase engine resources. The engine is not such a load in the cold season.
But, after the engine starts and is warm enough, the glow plugs for the diesel engine change their role. Now they help in the process of spraying fuel. The point here is that diesel fuel that is fed into the cylinders through the injectors directly collides with the candle.So, in the cylinder the process of turbulence is formed. This significantly improves the formation of the fuel mixture.
Varieties and device
Diesel glow plug in appearance can be somewhat reminiscent of a candle for gasoline engines. But at the same time diesel analogues do not produce a spark. This part is equipped with a spiral metal or ceramic heating element.
A metal tip may consist of several spirals. There are two of them. One of them is heating, the second is adjusting. The first helix is necessary in order to ensure the fastest possible heating of the tip. The second, adjusting, is protection against overheating. The system is triggered by the resistance of the spiral, which increases with increasing temperature. This is a typical scheme of glow plugs.
There is space between the spirals. It must be filled with a special filler. It has good insulating properties. Here this filler performs several functions. This protection of the spiral from various influences, as well as more efficient heat transfer.A glow plug equipped with metal spirals can easily warm up to 1000 degrees.
Candles with a ceramic heater
Such details are similar in principle to their work. The difference of its design is that the spiral is enclosed in a shell of ceramic materials. So, heating is carried out even faster, and power will be even higher. To warm up a part to a maximum temperature of 1350 degrees, one second is enough.
Glow plugs for diesel with one helix
The part with this design is equipped with a single helix, which performs the function of heating and adjustment, which is very necessary for almost instantaneous heating to operating temperatures.
In most diesel engines, this design fully meets all requirements, the part heats up quickly, and its service life is rather high.
The development of technology is gradually replacing such parts, and replace them with double-helix structures. This is due to the fact that the double-glow plug has the best and flexible temperature adjustment options.
The heating elements are located directly in the cylinders of diesel engines.They are located exactly where the turbulence of the fuel mixture. When the driver of the car turns the key, voltage is applied to the candle. At this point, it is very efficiently heated. The driver will see a lit indicator on the dashboard of the car. For heating to operating temperatures, the heating element will take about 5 seconds. Naturally, this time depends on the current air temperature.
Further, the glow plug is already warm enough and works in order to warm up the cylinders themselves and the air in them. But this time is not enough to effectively heat the cold cylinders. In addition, the air is constantly updated on the cold outside.
the main objective
The main purpose of this part is to heat the fuel to evaporation temperature. Then the fuel is perfectly mixed with air and immediately lights up, but by compression. After the corresponding indicator on the dashboard goes out, you can proceed to start the motor.
Glow Plug Relay
Naturally, these devices need to be managed. For this, diesel engines have a special relay or a separate control unit.Both devices are necessary in order to regulate the voltage that will be supplied to the candles. They also serve to adjust the temperature and duration of heating. The operation of this relay depends on the readings of the coolant temperature sensor and the crankshaft speed sensor. This is how glow plugs are controlled in diesel engines.
Modern diesel units provide besides warming up before starting additional heating already after the engine is started. This feature helps to reduce noise when the engine is running, and also significantly reduces harmful emissions into the atmosphere. Directly for the heat it takes a few minutes. And it will stop if the temperature of the coolant reaches 30 degrees. Thus, the glow plug unit affects the quality of work and engine start in cold time and on the resource.
Check the operation of the spark on diesel
Sometimes these parts can fail. In order to check the health of candles, there are several ways. This is done both with the direct help of the motor, and in general without an engine.
To check without a motor will need some devices. This is an ohmmeter or voltmeter.So you can check the status of the voltage. If there are no devices, then it is worth using another method. For example, the test candle must be connected to the battery plus, and the minus to the cell body.
A working candle will literally heat up a spiral in a couple of seconds, and it will glow. If this does not happen, then replacement of glow plugs is necessary.
Another way is to use a tire. For this you need to install on her twisted parts. The ends of the candles must be directed upwards. Next, with the help of wires with a large cross-section, you need to close the mass by connecting the body of each candle.
Many of the instructions for repair and maintenance of motors write about the method of testing performance through the holes for the injectors. Removing the nozzles, observe the glow of the pins due to heating. If some do not burn as brightly as others or do not glow at all, then you can check the connections and resistance indicators.
How to check the glow plug relay? For this you need a tester. To start checking you need to disable it. Now connect the tester to the terminals on the motor, as well as to the ground.If there is no voltage, check the voltage supply from the battery.
Next, connect the tester to the opposite terminal. After that we start the car. Now we do the same as in the first case. If the voltage does not go, then you need to check the high-voltage wire. Here the wire must be connected to the spark. If everything works, then a replacement relay.
In addition, there is a way to test the relay with an ohmmeter. So. Check the resistance between terminal 30 and 87. Then we apply voltage to terminals 85 and 86. If the relay does not work, and the resistance is not zero, then the relay is for replacement.
The main reasons for the failure of candles
Usually, these parts can leave standing for two reasons. Either this is the end of life, or else the failure of the fuel system of the car. It is worth knowing that if at least one candle has failed, it is recommended to replace all of them completely.
With regard to malfunctions of the fuel system, in the case of wear or pollution of the injectors diesel fuel gets to the heater. Then a hole is formed on the body of the heater and the spiral is destroyed. In addition, you can damage this part during installation.
If all the candles are out of order at once, then you need to diagnose the entire electrical part of the car.
How to replace glow plugs?
These parts are located in the upper parts of the cylinder head. To replace the need to disconnect the wires, which are located under the head cover. Remove the wires connected directly to the spark plugs.
Next, with a wrench, all parts are unscrewed. Need to work carefully. After that, clean the contacts, battery terminals, and spark plug wires well. The holes in which the candles were screwed in must also be cleaned. To do this, you can use the scan.
After the replacement, you should tighten the spark plug, but not much. If the tightening is stronger than necessary, then the next replacement can break the part. And this is an expensive repair. But it is also not worth very little to twist the part, as there is a risk that it will simply unscrew on the go. Now it remains only to connect all the wires back. Everything, replacement of diesel glow plugs successfully completed.