Why are Injectors Often Easy to Break? Just Take off and You'll Know!

From: http://www.sinocmpinjector.com

The fuel injector is the most precise component in an electronically controlled diesel engine. Its role is to spray up to 160 MPa of fuel into the cylinder for combustion. For a diesel engine rating at 1900 revolutions, there are 16 injection processes per second on average, and each injection process is divided into 3-5 small injections such as pre-injection and main injection harsh.

Dismantling Bosch Injector, Exploring Cause of Damage
Injectors have extremely strict requirements for the cleanliness of fuel. Water or impurities above 5 microns can cause damage. Poor quality filters are difficult to intercept the impurities and water in the fuel, causing damage to many of excavator owner's injectors. What the inside of the damaged injector looks like may not be seen by many friends. Today I'll disassembling an injector that has been severely worn, let us check it out.

This is an electronically controlled fuel injector from Bosch in Germany. At present, most of the fuel systems of domestic electronically controlled diesel engines apply this company's products. It's worth a lot, and each one costs more than $150. For a six-cylinder engine, if you replace it all, you will lose about $900.

First remove the solenoid valve on the top of the injector. The role of the solenoid valve is to control the fuel injection. Let the fuel be injected into the cylinder at the correct flow rate and at the correct time.

This part is the valve assembly in the injector. It is one of the most easily worn parts inside the injector.

The two parts in the plate are valve stems. For comparison, we have specially found a new valve stem for comparison. It's a worn valve stem on the left and  a brand new one on the right.

Zooming on the lens, it can be seen from the comparison that the left valve stem has been severely worn, which is almost fatal to the injector.









Needle valve is worn Nozzle becomes larger

Let's look at the bonnet again. The pit on the bonnet is also one of the parts that are prone to wear. There will be a steel ball in the pit. The solenoid valve controls the fuel injection through it. After the inside of the pit is worn, the amount of oil returned to the injector will increase due to the tight closing of the steel ball, which will cause the needle valve to close tightly.

These dimples are very small, and in order to capture the details, I used a Canon Budweiser macro lens. Even so, it is still difficult to see clearly, which is enough to show how precise the machining of the parts inside the injector.

This part is the injector nozzle, and the fuel is injected into the cylinder from its head. In the entire injector, its working environment is the worst because it directly faces the extreme working environment of high temperature and high pressure in the cylinder.

The tip of the needle valve of the nozzle plays a role of sealing the fuel. When fuel injection is not needed, it must be leak-proof. It can be clearly seen from the photo that the tip of the needle valve of this nozzle has been severely worn, and it is likely to cause the injector to drip oil when working. Drip oil from the injector can cause the piston to overheat locally and even cause the piston to perforate.

Finally, let's look at the orifices of the injector nozzles. They are used to inject fuel into the cylinder. They are so small in diameter that they are almost invisible to the naked eye. The diameter of the hole is directly related to the injection amount per unit time. If the fuel contains particulate impurities, it will cause irreparable wear to the injection hole. Over time, the diameter of the nozzle will become larger and larger. As a result of the larger nozzle holes, the amount of oil supplied increases, causing torque to exceed the limit, black smoke, and high fuel consumption.

Obviously, the nozzle hole on the left is significantly larger than the brand new hole on the right. In other words, the nozzle on the left has been severely worn and can no longer be used.

Not damage, no greedy.
The fuel injector is a very precise whole. If any one of the points is out of order, its performance will be greatly reduced. Black smoke, insufficient power, high fuel consumption, and even difficult start-ups will be followed by a series of failures. To repair them, only a very large cost of money and time can be paid.

However, you don't have to worry too much. As long as you insist on using genuine filters and adding high-quality oil, the actual life of the injector is very long, and it can even reach the same life as the entire vehicle.