How to identify a cylinder heater failure?

When on a cold winter morning you make contact on yours diesel to the car, you will notice a spiral shaped lamp that will turn off a little later than the others. This is a sign that the heaters have heated the mixture in the cylinders and thus allowed the engine to start.

So, to ignite a mixture of fuel and air at diesel engine no spark plugs required as in gasoline. The explosion of this mixture, which is a basic requirement for the operation of an internal combustion engine, is due to the high pressure created by a special pump.

However, to ensure that the engine is always reliable, especially at low outside temperatures, diesel engines also rely on the help of the heaters located in each cylinder's head.

They are especially important with older models, because without their help you can't start the engine even when the temperatures are in the positive. In newer models, they burn only below -4 degrees. That's why heaters in newer cars last a long time. Manufacturers advise replacing them at about 80.000 to 100.000 kilometers. But why are heaters so important?

During long periods when the engine is not running, the combustion chambers and the engine block cool down quite a bit. When the already quite cold outside air that is sucked into the cylinders is added to that, the temperature obtained by compressing the mixture does not allow it to ignite on its own.

Parts of the heater

At that moment the heaters enter the scene. They are screwed into the cylinder heads, and their tip, which reaches the combustion chamber, is heated to high temperatures as soon as it receives electricity. Depending on the type of heater, it reaches temperatures in excess of 1.000 ° C in just a few seconds, thus warming the mixture up quickly. This warming process that occurs before the engine is started is also called "preheating".

At the start of preheating, current flows through the conductors in the heater and the control coil to reach the coil at the top of the heater, which soon reaches the boiling point. If the vehicle's heaters are not working properly, it is easy to conclude that the engine will be difficult to start in colder weather, or it will not be possible to start it at all. How do we know it's time to replace the heater?

Of course, the best indication that the heaters are not in good condition is the inability to start the diesel engine, when the key is heard turning and the engine does not start.

However, in order not to get into a situation where you cannot start the engine at all, you should react when symptoms suggesting such an outcome occur.

One of them is the difficulty of starting the machine, which especially occurs on cold mornings. Even when you start the engine, it will have a very rough run until it warms up. This is caused by poor ignition of the mixture, as the heaters do not heat the inside of the cylinders sufficiently. The result is incomplete combustion of the mixture. Even when you start the engine after a couple of tries, you will probably have the same problem when you leave the car for a couple of hours in the parking lot.

The thick white smoke exiting the exhaust while the engine is cold is another sign that the heaters are not working. Since the mixture does not burn completely, the fuel enters the exhaust system, resulting in smoke. When the engine reaches operating temperature, the smoke disappears.

Of course, all these symptoms can occur at once. So, if the engine of your vehicle is having a difficult start and when it finally starts running roughly and releasing white smoke until it warms up, you can be almost certain that the problem is with the heaters.

Sometimes the heater can stop working due to a relay failure. With newer models, this is regulated by electronics. It will not affect the engine, but the heater will be damaged very quickly.

The price of the heater, depending on the engine, ranges from about five to over 20 euros.

With a little experience and tools, you can replace them yourself

You can also change the vehicle heaters yourself. You will only need a little experience and a screwdriver, the so-called gedora. You should find the heaters very easy. They are located at the top of the engine block, arranged so that their top enters the cylinders. Replacement is a process that takes about 30 minutes.

To remove the heaters, first unplug the cables that are attached to them, then release the screws that hold them in place, and finally remove them from the engine. Test them to make sure they are still usable. You only need the engine start cables for this. Connect the red cable to the top of the heater and the black to the heater body. If the heater is working properly, its tip will start to glow. So do not hold the heater by the top when doing this test.

In case the top does not shine, the heater is not operational.