Injectors for common rail diesel
08.11.2024
Modern diesel engines from around 2002 onwards have common rail injection at Volvo and Saab. This has now established itself in the entire passenger car sector, thanks to its extremely precise controllability and quiet, clean combustion, in comparison to distributor pumps or pump-nozzle systems.
In common rail direct injection, the high-pressure pump generates a consistently high pressure in a common line in front of the injectors, which is regulated by a metering unit on the high-pressure pump. The injection valves, also known as injectors, are controlled by the engine control unit based on a number of parameters and release a precisely metered amount of fuel at an extremely high pressure, finely atomized and precisely timed, directly into the combustion chambers.
The injectors are subject to high loads, and despite fine filtering, deposits occasionally occur due to fluctuating diesel quality. In addition to abrasion, the high pressures also cause fatigue in the springs inside the injectors.
These factors cause the precision of the injectors to decrease. The first signs of wear are indicated by poorer starting due to the decreasing pressure in the rail, followed by clouds of smoke, especially when starting. In addition to polluting the environment with smoke, dripping, leaking injectors also place a considerable strain on the engine oil and the particulate filter. If nothing is done when the oil level rises, this will lead to engine damage in the medium term.
In the worst case, engine oil that has been thinned by leaking injectors can cause the engine to speed up uncontrollably. This is because diesel evaporates when the temperature rises and enters the intake air via the crankcase ventilation.
Injector wear is dependent on maintenance and use, but usually occurs for the first time at mileages between 250,000 and 300,000 kilometers. However, it can happen earlier if the fuel filter is neglected during maintenance or the system is not bled correctly after the filter has been replaced. The injectors depend on the cooling and lubricating properties of the diesel for proper functioning.
In any case, if a common rail diesel engine is malfunctioning or running roughly, the cause should be thoroughly investigated. Even minor problems such as defective temperature sensors or pressure difference sensors can cause high follow-up costs if they are not replaced.
Injectors should only be installed in reliable quality. Only these ensure perfect engine running in the long term.
Some of the replacement parts available on the market are not cleaned and overhauled according to the manufacturer's specifications, and premature failures do occur from time to time.
We recently experienced this impressively on a 2013 V40 D2 with around 297tkm: after installing new injectors, the poor cold start, clouds of smoke when accelerating and rising engine oil level were history. Of course, we also changed the diluted engine oil.
Suitable for:
all Volvo and Saab with common rail injection