Diesel engines have become increasingly popular in cars and vans in the UK over the past couple of decades. While diesel vehicles offer great fuel economy and torque, they can suffer from some common problems. Here are some of the most typical issues experienced with diesel cars and vans.
Diesel Particulate Filter Blockages
Modern diesel engines are fitted with a diesel particulate filter (DPF) in the exhaust system to reduce particulate emissions. The DPF traps soot particles, but it can become blocked over time as soot builds up. This causes restriction in the exhaust system which reduces performance and fuel economy. Warning lights will illuminate on the dashboard if the DPF needs regeneration at a DPF treatment Birmingham centre to burn off the excess soot. If ignored, the filter will eventually become totally blocked, requiring replacement.
Injector Problems
Diesel engines use high pressure common rail fuel injection systems. The injectors have very tight tolerances and are under immense pressures, so they can be prone to blocking or failing over time. Contaminants in poor quality fuel can cause them to stick or seize. Warning lights relating to injector problems will appear on the dashboard, and diagnosis requires specialised diagnostic equipment. Injectors can sometimes be cleaned or repaired, otherwise full replacement is required.
Turbocharger Failures
Most modern diesel engines are turbocharged to increase power. The turbocharger consists of a turbine and compressor on a shared shaft. As exhaust gases spin the turbine, the compressor pressurises intake air. Over time, the turbo’s bearings can wear out, causing rattling noises on start up. The turbo may fail completely due to oil starvation, foreign object damage or carbon build up. Replacement turbos can be costly, so regular maintenance is recommended.
EGR Valve Issues
Diesel cars use exhaust gas recirculation (EGR) valves to reduce NOx emissions. The EGR valve recirculates a measured amount of exhaust gas back into the intake manifold. However, the valve can become clogged with soot over time. This causes rough running, increased emissions and poor performance. The EGR valve needs cleaning or replacing when faulty.
Oil Dilution
Some amount of fuel dilution in engine oil is normal in diesel engines. However, excessive fuel dilution can occur in cold weather due to incomplete combustion. This reduces the oil’s lubricity and can lead to increased engine wear. Oil dilution can require premature oil changes in affected vehicles.
Diesel Fuel System Problems
Modern common rail diesel systems operate at extremely high fuel pressures. Any faults in the high pressure fuel pump, injectors, rail or pipes can be very expensive to repair. Fuel leaks can also occur on older diesel vehicles from pipes corrosion. Keeping the fuel system well maintained is key to prevent problems.
Common issues with diesel cars and vans include DPF blockages, injector faults, turbocharger failures, EGR valve issues, oil dilution, and fuel system problems. Staying on top of routine maintenance and addressing any warning lights promptly is key to avoiding major repair bills. Using high quality fuel and oils also helps minimise problems.