A faulty diesel injector often sounds like a loud, sharp ticking, rattling, or knocking noise, sometimes described as a "machine-gun" or "death rattle," particularly during acceleration or at idle, indicating uncontrolled fuel combustion, which can also manifest as rough idling, reduced power, or hard starting.
We have had a couple of customers with diesel injectors needing fixing, and these are 4 signs that yours need maintenance:
Severe symptoms (strong smells, heavy smoke, loud knocks): In these cases, fuel injector cleaner is unlikely to help, and professional mechanical repair is necessary.
Short answer: You should not drive a diesel vehicle with a stuck injector except for a very short, controlled move to get the vehicle off the road or into a repair bay. Driving normally risks severe engine damage, reduced control, and safety hazards.
Direct injection and common-rail diesel injectors
The cost of replacing fuel injectors in diesel engines can vary significantly depending on the vehicle model and injector design. Diesel injectors typically range from £150 to £250 each, with prices exceeding £300 in some high-performance or specialised models.
Poor Engine Performance
One of the first signs of clogged diesel fuel injectors is diminished engine performance. This can present itself in different ways: difficulty starting your vehicle, rough idling, lack of power when accelerating, or even stalling.
Most diesel injector noise can be dramatically reduced using proven methods that range from simple fuel additives to mechanical fixes. Quick Solutions for Diesel Injector Noise: Fuel additives - Lubricity improvers and detergents (easiest fix) Mechanical cleaning - Ultrasonic cleaning and nozzle testing.
Although most fuel injector cleaners begin working immediately, it takes time before the improvements become noticeable. Before the cleaners start working effectively, the vehicle should travel several hundred miles and burn a good portion of a full fuel tank.
Ticking diesel knock sounds are usually high-pitched and consistent in tempo. Drivers may notice them while driving without hitting the accelerator. A rattling diesel knock sound is fast and shaky, which may get louder with acceleration. This sound is generally one of the easiest ones to detect.
Position Injectors: Place the injectors in a clear area where you can observe the spray pattern. Crank the Engine: Have someone crank the engine while you observe the spray. Check Spray Pattern: Look for a fine, even spray. Irregular patterns indicate clogs or damage.
The test costs from £15.00 + VAT per injector. If you need us to remove the injectors to carry out the test we charge labour to do this according to where they are & what needs to be removed to access the injectors. PD injectors ( Pumpe Duse) can be sent away for testing. This will take 4-5 working days.
Contamination & Clogging: Dirt, carbon, or poor-quality fuel can clog the injector, reducing fuel flow and causing misfires. Electrical Issues: Wiring or solenoid problems can prevent the injector from opening properly, leading to poor engine performance or a check engine light.
Fuel injectors work as a set, and replacing just one can lead to imbalances in your engine's performance. When one injector fails, it often indicates that the others are nearing the end of their lifespans too. Replacing all injectors at once ensures consistent fuel delivery and optimal engine performance.
At a professional garage, they may use an ultrasonic machine to clean the injectors out. Those who have some mechanical skill can pull the injectors themselves, disassemble them, and clean the parts in an acetone bath and wire brushes.
Signs of dirty fuel injectors: Apply the fuel injector cleaner if you notice the above-mentioned signs of dirty fuel injectors, such as reduced fuel efficiency, rough idling or misfires, engine hesitation or knocking, difficulty starting, etc.
5 Common Signs of a Failing Turbocharger
Improperly timed fuel injectors are the most likely cause of your engine's knocking sound, so getting a fuel additive to help lube them up may solve the problem.
This is because the injectors are not delivering the right fuel to the engine, which can cause the check engine light to become active. For example, if the fuel-air mixture is not correct, your car's O2 sensor will throw an error code resulting in an active check engine light.
Spray penetrating oil like WD-40 or PB B'laster on the injection pump. You might need to let it soak overnight so you can continue unsticking a stuck injection pump. Gently tap the pump if necessary to help free it up.
A common fault is from contamination or by general wear and tear, as the nozzle can become blocked with carbon or foreign matter. This is a common problem if alternative fuel has been used.
A dirty fuel injector can affect your car's performance, but it doesn't always need to be replaced. Sometimes a good cleaning can solve any issues, at least temporarily.