When you need an engine with steady torque and pulling power without sacrificing fuel economy, diesel engines are the preferred choice. Diesel engines have a fuel efficiency of roughly 40 percent more than gas engines and as such, they're a good source of reliable power. However, the engine is massive and heavy to offset the stress of high compression, which makes this engine a bit pricey compared to gasoline engines.
Kelly Grant, of Bill Grant Ford-Mercury recommends customers follow the manufacturer recommendation on oil and filter maintenance to improve diesel performance and downtime.
"Many of the poor-start/no-start conditions we see in the service department stem from applying older diesel maintenance standards to these modern emission-controlled engines," Grant said.
"Due to government-mandated emission standards, modern diesel truck engines have computer-controlled direct injection. Proper flow of oil to each fuel injector is critical for engine start."
Six Points of Diesel Engines
1. Unlike the gas engines, a diesel engine has no electrical ignition parts like plugs, wires and moving parts like a distributor rotor, which is subject to wear. These parts have a limited life and have to be changed on a regular basis. Because of this, this is one chore diesel engine owners don’t have to worry about.
2. Diesel engines run at higher compression pressures than gasoline engines. Where the highest compression for most high performance gasoline engines is close to 200 psi, a diesel runs at almost three times that pressure. As a consequence, more heat is generated, putting extra demands on the engine cooling system. Studies show diesel engines usually fail 50 percent more on cooling-related problems because they cannot stand prolonged overheating.
3. Gaskets on diesel engines must be monitored closely since they are exposed to extreme operating conditions. If possible, all mounting bolts must be re-torqued at regular intervals to prevent leaks, especially in the combustion mounting areas. This is also true for coolant hoses which can deteriorate quickly if not secured properly. A lot of this is also caused by engine vibrations, which is common on diesel engines. Always replace a leaky gasket as a set. If one starts to leak, the rest are not far behind.
4. Since diesel engines use a lot of air, greater attention is paid to the engine air filtration. A common practice among truckers is to install a tell-tale plastic indicator on the side of the air filter housing. The indicator changes color as soon as the engine filter element becomes dirty. Cooling this air is also critical especially if the engine is turbocharged. On some high end diesel engines they are fitted with after coolers to cool the air from turbo charger.
5. The oil filter selection is very important on diesel engines because of the bad elements of sulfur residue and carbon created when fuel is not burn completely. The filter used must meet or exceed the OEM filter recommended by the vehicle manufacturer. This will ensure that all corrosive particles are removed from the oil. Using synthetic oil will also help because the additives in the oil will resist premature breakdown.
6. The fuel system maintenance is handled in various ways. Always keep the fuel tank full to prevent condensation from building inside the tank which can end up in the fuel injectors. This also requires changing the fuel filters as recommended to prevent moisture build up.
Diesel Fuel
While diesel fuel comes out of the same barrel of crude oil as gasoline, it is a middle distillate, meaning it has a higher boiling point and, therefore, a higher energy value than gasoline.
A diesel fuel's cetane number is one closely associated with how it will perform in cold temperatures because it is a measure of the ease with which the fuel is ignited. Most electronic diesel engines require a cetane rating of 45 or higher. In cold temperatures, a vehicle will respond to a high cetane rating with better engine performance, better fuel economy and better exhaust emissions. On the other hand, low cetane fuel (below 40) will cause white smoke, poor fuel economy and the lack of power in cold weather.
A proactive stance is the best way to avoid cold temperature-induced fuel filter plugging. But first realize that, in addition to waxing, filters can plug from a variety of causes. In winter temperatures, even small quantities of water can cause plugging. At any temperature, common dirt or bacteria and algae can grow in a poorly maintained fuel storage system causing filter problems. These can normally be avoided by keeping the fuel storage system clean and dry. Be sure to drain accumulated water frequently and use dispenser filters when filling the vehicle tank.
Filling fuel tanks before shutting engines down for long periods of time helps eliminate condensation. Also fuel/water separators help minimize entrapped water in the fuel, but make certain that they're serviced regularly.
Low-temperature Operability of the Fuel
Kelly Grant said, "During cold-start conditions, poor oil viscosity can affect injector performance immediately following start-up, resulting in rough idle, excessive smoke, and poor power. The manufacturer recommends a proper warm-up of the engine before asking it for peak performance.
After warm-up, long idle times and driving at reduced power can actually contribute to injector problems, EGR contamination and turbo failures in engines built since Jan. 1, 2003, under mandated emissions standards."
There are several approaches to ensure proper fuel flow to the engine in cold weather. The fuel itself can be conditioned. Keeping the engine running is, unfortunately, considered to be a viable solution by some operations, but it's expensive over the long term. We're left with the option of heating the fuel. Return fuel heaters allow the engine-heated "return fuel" to flow back to the inlet side of the fuel filter instead of directly back to the tank. The warm return fuel makes up a major portion of the inlet fuel, reducing the amount of cold fuel supplied from the tank. A thermally controlled valve diverts all the return fuel to the fuel tank when the fuel in the tank is warm.
Engine coolant is another source of heat energy that, through the use of a heat exchanger, can transfer excess cooling system heat to the fuel. In conjunction with electric heat at engine startup, a coolant/fuel heat exchanger can effectively eliminate fuel filter plugging due to waxing.
This information was compiled from "Fleet Equipment."
