In our first blog, we look at some of the problems modern diesels experience and highlight how, by following a few simple rules, you can help prevent serious maintenance headaches.
There was a time when diesel engines were technologically simpler than their petrol equivalents. However, ever-tightening global exhaust emission and fuel efficiency regulations have resulted in diesel engines becoming more advanced, and in many cases far more complex than petrol engines. With this added complexity comes the potential for higher maintenance and repair costs.
Fortunately, the latest generation of diesel engines have been around long enough for the team at John Dale Motors to build up a huge knowledge base of best practice expertise to enable us to diagnose diesel problems quickly and accurately, fix them first time and importantly, advise our customers on how many of these problems can be avoided by following a few simple rules.
So let’s take a look at some of the problem areas …
The exhaust gas recirculation valve, or EGR valve, recirculates exhaust gas back into the engine intake system for increased engine efficiency, reduced fuel consumption and lower NOx emissions.
The exhaust gas re-entering the intake system effectively changes the air entering the engine. This diluted mixture burns slower, lowering temperatures in the combustion chamber by almost 150°C, and reducing poisonous NOx production for cleaner, more efficient exhaust emissions.
EGR valves are subject to wear and tear over time. However, the single biggest cause of failure is the build-up of carbon particles from the exhaust gases in the EGR and intake system passages. Over time this will clog tubes, exhaust gas channels and eventually the valve’s plunger mechanism, causing it to either stick open or closed. Failures can also be caused by a rupture or leak in the valve diaphragm.
The symptoms associated with EGR valve failure include:
A diesel particulate filter is a trap that captures and stores exhaust soot in order to reduce particulate emissions from diesel exhausts. Because they only have a limited capacity, this trapped soot must be periodically emptied or ‘burned off’ to clean the DPF and avoid blockage of the filter.
This regeneration process burns off the excess soot deposited in the filter, reducing the harmful black smoke you see from diesel vehicles, particularly when accelerating.
To make sure that the regeneration takes place, most manufacturers suggest that every few hundred kilometres, the vehicle is driven for a period of more than thirty minutes at a consistent speed in excess of 60 kph. Doing this will trigger a DPF regeneration to clean out the filter.
Short journeys at low speeds are the prime cause of blocked diesel particulate filters.
If blockage does occur, the DPF won’t be able to regenerate itself and will need to be cleaned or even replaced. Should the DPF need to be replaced, most manufacturers’ warranties will not cover the cost if the fault is deemed to have been caused by the owner’s driving style rather than a fault with the filter itself, potentially leaving you with a four-figure bill.
A DPF should last for around 200,000 kilometres, but on a poorly serviced vehicle may fail sooner. Check the recommended service intervals for your vehicle, and always make sure it is serviced on time.
It’s also important your workshop uses exactly the right type of oil – using the wrong oil can create by-products that block these filters.
Carbon build-up on diesel engine components such as valves, fuel injectors and intake manifolds is a big problem. Carbon is like cholesterol, it slowly builds up over time, helping to block intake manifolds and restrict airflow through the inlet valves.
Causes include the use of poor-quality fuel, frequent short-distance trips, excessive idling, and infrequent oil changes.
This carbon build-up will slowly rob your engine of power and fuel economy. Tell-tale signs are check engine lights on, rough running and poor performance and fuel economy. Usually, when it gets to this stage, your vehicle is suffering from a heavy build-up of carbon in the induction system.
As always, preventative maintenance is the key, and we recommend regular cleaning of the intake and fuel system to ensure that carbon never builds up to the level where your vehicle will experience drivability issues or need expensive repairs.
There’s no point beating around the bush – fixing many of these problems on modern diesels can be expensive. For example, Diesel Particulate Filters alone can cost thousands of dollars, so we’ve compiled a list of things you can do to keep your diesel in tip-top health and prevent frustrating running problems and unexpected repair bills.
At John Dale Motors, our team of experienced technicians are experts in the servicing of all makes and models of diesel vehicles, including passenger cars, four-wheel drives and commercial vehicles.
Our ongoing training ensures we stay ahead of the latest diesel engine technology and problem-solving techniques, to keep you on the road and unexpected repair bills at a minimum.
