With the hike in fuel prices, we are seeing a lot of first time buyers of diesel cars. And these buyers have a lot of apprehensions about owning a diesel engine, the most pressing of which – aren’t diesel engines higher on maintenance?
A few years ago, we would have said, yes, diesels demand a lot more tender loving care than petrol engines. But with the advancement in technology, modern common-rail diesel engines are very well built and if you stick with the manufacturers’ recommended service routines you will get thousands of trouble-free kilometers from your diesel car.
In fact, since diesel engines run under high pressure and compression ratios, they are generally built much tougher than petrol engines, and hence wear and tear too takes longer on a diesel engine. Diesel engines also develop much higher torque and can pull better than petrol engines, making them on average atleast 20% more fuel efficient than equivalent petrol engines.
However, if you want to enjoy a long-standing relationship with your diesel car, here are a few quick pointers to follow, to ensure trouble-free motoring.
Warm it up
Diesel engines clatter when they are cold. That’s because diesel engines rely on the heat generated by compressing air in the cylinders in the engine for the diesel to ignite, and when this air is too cold, combustion is not too efficient. When you start a diesel engine for the first time in the day, don’t press the accelerator pedal (this is all the more important for modern common-rail diesel engines, where the ECU adjusts all the parameters for optimum combustion). Crank the engine and when it fires just let it idle for about a minute or more. This gives the engine ample time to circulate oil efficiently and gives the cylinders enough time to build up heat for efficient combustion.
Care for the Turbocharger
The turbocharger in modern common-rail diesel engines is one of the most critical components in the engine. It spins at a very high rpm (the turbocharger spins at about 12,000 rpm, when the engine is doing only 1,000 rpm), compressing air to high pressure and forcing it into the engine. Because the turbocharger spins at such high rpm, it is important to make sure it is adequately lubricated. Before you turn the engine off, it is important to let the car idle for at least 30 seconds, allowing the turbo to cool down and get to minimum rpm, to avoid damage to the bearings.
Breathe clean air
Diesel engines rely heavily on high volumes of air for efficient combustion. This means that you need to keep your air filter clean at all times. Even small quantities of dust in the air filter can result in quite a bit of loss in performance. Get your air filter cleaned every 5,000 km or even sooner if you drive in very dusty conditions. Replace the filter element every 15,000 km if possible or if you are using a high-performance filter (such as K&N or Green Cotton), clean and lubricate it regularly.
Mind that oil
Engine oils have to work much harder in diesel engines because of the larger number of moving parts and greater heat tolerances. More expensive cars use synthetic engine oils that last about 15,000 km before a change. However, these oils are expensive and cost upwards of Rs. 1,000 per litre. Mineral oils and blended oils also work well, but require changing every 7,500 to 10,000 km. They are however cheaper. Oil in diesel engines tends to get blackened within just a few hundred kilometers of running, but this isn’t something to worry about. What you need to check is for build up of sludge under the oil cap or change in the viscosity of the oil. It’s best to follow the manufacturer’s recommended oil change routine. Use only oils recommended for diesel engines.
Keep the injectors clean
Diesel injectors in modern common-rail diesel engines are quite sophisticated. They are electronically controlled and spurt precise amounts of diesel fuel directly in the cylinder, sometimes multiple times per combustion cycle, in fractions of a second. Even the slightest bit of soot or sludge can clog up the injectors, resulting in loss of power and clouds of black smoke from the exhaust. Use a branded diesel injector cleaner additive every month or every four tankfuls to keep the injectors in prime condition. You could also use premium diesel every four tankfuls, if you don’t do so with every tank. Premium diesel contains additives that help keep the injectors clean and improve combustion.
Do not let the tank run dry
A car that runs on diesel hates running empty. If you are unfortunate enough to drain the last drop of diesel from your car, you will be in for a tough time, as diesel engines immediately get an airlock in the fuel lines. When you refuel, you will then need to manually “prime” the diesel pump in the engine to get the diesel to flow smoothly to the engine again. This can be a bit messy. The easy way out is to make sure the tank never runs dry. Always top up when your car’s fuel gauge reaches the reserve fuel mark.
Drive with optimum throttle
Flooring the throttle in a modern diesel engine does not give you more power. It just wastes more fuel, as torque in a diesel engine is generated quite low down in the rev band. Instead, learn how to ride the torque curve in a diesel engine. Find the sweet spot where you get maximum torque (you can get this from the owner’s manual in your car – usually around 1,800-2,200 rpm in small diesels), and keep shifting within the torque band. You’ll get both power and mileage in this range. However, on the flip side, don’t use too little throttle too as this leads to soot build up in the exhaust system. Once in a way, let the car rev close to the redline to clear out any soot build up in the exhaust.
Once you get into the habit of driving a diesel car and experience the many benefits, both economically and drivability, it’s hard to find reasons to not own a diesel car. A little bit of tender loving care can make a diesel engine last a lifetime.