We put the wrench in the hole and make it fit on the head of the spark plug. We use the spanner to

The function of these heaters is to heat the oil to be burned in the process of starting the engine. In gasoline engines, it explodes when the spark at the spark plug. In the case of diesel serving food engines diesel explodes but not "burn" it burns. For diesel burn this has to be at a temperature (and pressure) determined. So when a cold engine glow plugs heat the diesel combustion is easier. To do this the tip of the spark plug gets "red" heating the oil that is around you. When the engine is running these plugs are "off" so to speak, unlike gasoline engines in which the spark plugs are generating serving food continuously.
What they have done is connect directly to a car battery to see what happens in the heater. serving food As we will see this is one of the ways that exist to see that the heater is failing.
As we have already mentioned to start the car (this being cold) water heaters are activated for a few seconds. This activation is reflected in a yellow "sneak" (orange?) serving food That we have on the dashboard with a drawing in the form of spring or resistance. Normally this indicator lights for a few seconds then goes to boot.
A heater spoiled with diesel serving food generally tear without difficulty provided the temperature is not too low. With two spoiled and cold in the room to the car boot ... it will cost even refuse to do so.
I will recommend replacing the 4 heaters at once, because if one fails, serving food the other three will be left with a lot of life and it is likely to fail soon, but good considering the time in which we live is not more power maximum economy and replace one.
Will disconnect serving food the car ignition. Disconnect the spark plug wire we will check. Selected in the ohms scale tester (resistance). We place the positive serving food terminal (red wire) Part hovering spark plug, ie, where the cap was connected serving food we disconnected. The negative terminal of the tester (black cable) we place touching ground: for exam ple the cylinder head, a screw to the chassis of the car, etc. The tester has to give us a very low reading of 1-3 ohm (or near these values). If resisitencia (read the display) is very high means that the heater is damaged (broken spark coil).
This method can "fail" as there may be a heater that works, but just warm. Method 2: Direct connection to the battery. As shown in the beginning of the video input. Be very careful serving food .... How much do they cost? I have bought in Oscaro for 22 each. They also have other brands, more expensive and cheaper, to consumer tastes.
There are more online stores and spares can ask at your usual store spare parts. I have taken the order to buy the filters as soon I have to replace it. What tools are needed? I used a key number 10. You can use a pipe wrench vessels but these have to be quite long because otherwise the protruding serving food portion of the spark plug (where the cable is connected) will stick in the bottom of the glass and you can not use it.
This key've had to "wear" with a honing serving food stone because although I tried plugs I bought and encaba perfectly, did not fit into the recess in the cylinder head (I bought it in LEROYMERLIN for about 7 ).
You can see that the "cup" on the right is narrower than the left, while in the first photo were virtually identical. I have also used a spanner 10-11 to rotate the wrench. Pliers.
Below the black cap on the right (which comes the black cable) is the glow plug. To remove this cap I helped pliers and it was quite hard and not much place to put your hand.
This is the cap that was connected to the spark plug. This particular one was stained with oil. It is the closest to the oil filler so it probably has been spotted with those "squirts" oil that I usually fall to fill.
We put the wrench in the hole and make it fit on the head of the spark plug. We use the spanner to loosen the plug and force. After a few laps loosens we can continue turning the wrench by hand.
To put the new plug: enter it in the hole and begins to rotate with wrench using the hand. It is almost impossible to screw crooked but do not force as you can damage the threads. serving food Near the end of all have to help the other key.