Top Ten Basic Diesel Engine Maintenance Secrets

Thinking of switching your gas engine to diesel engine? Consider these advantages:

Fuel Savings:

Most diesel engine fuel is 30% more efficient than gas powered engines. For example: on those old Volkswagen diesel engines, they average about 45-50 miles per gallon while newer models like TDIs can get over 60 mpg!

Engine Reliability:

Unlike most gas engines, diesel engines likes to run all the time. The engine life can last between 300-400k miles. The last current world record was made by MB (Benz) for two vehicles having 900k miles on the same original engine.

Gas engine emissions:

Emit less carbon dioxide and hydrocarbons over gas engines.

Less maintenance cost:

Diesel engine does not require "Tune Ups" because it does not have spark plugs which is a big plus in maintenance. All you need is to keep regular oil and filter, air filter change at scheduled interval.

When it comes to maintenance, how does diesel engine compare? Shown are some important highlights below:

1.) Unlike the gas engines, diesel engine has no electrical ignition parts like plugs, wires and moving part like distributor rotor which is subject to wear. These parts have a limited life and have to be changed on regular basis. Because of this, this is one chore we don’t have to worry about.

2.) Diesel engines run at higher compression pressure than gasoline engines. Where the highest compression for most high performance gasoline engines is close to 200 psi, diesel runs almost 3 times that pressure. As a consequence, more heat is generated putting extra demands on the engine cooling system. Study shows diesel engines usually fail 50% more on cooling related problems because it cannot stand prolong overheating. This is why the cooling system is a high maintenance issue.

Tips on basic diesel engine maintenance:

a.) Do you notice that when your gas engine overheats, you can stop it and rest the engine for a few minutes? Later you can re-start and the engine will be fine. If similar situation happens with your diesel engine, the engine is almost always damaged beyond repair. Knowing this tip can save you a lot of head ache when you owned a vehicle with diesel engine.

b.) On some diesel engines, the cooling system uses a coolant filter to control the acidity (or ph value) of the coolant. This filter ensures that the cylinder block does not have a build up of corrosive particles inside

c.) One advantage of using a coolant filter in your diesel engine is that besides applying a coat of protective lining to the surface engine metals (like your engine block), it also has an active anti-foaming chemical agent that protects the liquid's surface tension and thus reducing the creation of coolant bubbles. Since this chemical agent depletes over time, the coolant filter must be replaced periodically.

3.) Gaskets on diesel on 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 is 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.) Since the cooling system is critical on diesel engines, it is important that an early warning system should be in place. Located in the dash panel, the early warning device must be easily seen and heard. If the engine has already overheated and it was not caught on time, the engine could be damaged. Most trucks have this feature in their dash and must be checked regularly to see if early warning system works.

7.) 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. Some diesel engines use 2 types of fuel filters to control the presence of moisture in the engine. Some fuel tanks are also design with one way breather vents for the moisture to escape. This vent should be checked occasionally if there is a suspicion that it is restricted.

8.) Diesel engine has very little carbon monoxide, a poisonous gas common to gasoline engines. However, it produces a lot of black soot which is the result of incomplete combustion. Most of this is caused by dirty injectors and faulty injection timing that inject too much fuel. To ward this off, glow plugs are used to heat the combustion chamber to assist in burning the fuel. These glow plugs must be checked especially before winter season.

9.) During winter, diesel engines are normally hard to start and the best way to remedy this is to install an electrical heater to the cylinder block. Another way is to install a heater element in series with the heater hose. In extreme cases of hard starting, a starting fluid is sprayed on combustion chamber but use it sparingly to prevent scoring the cylinder walls at higher rpm.

10.) To prevent engine cylinder block scoring, avoid prolong idle of your diesel engines. A very common habit among drivers especially in winter... diesel engines are made to idle for long hours to keep the cab warm. When diesel engines are run longer in cold temperatures, insufficient lubrication to the piston wall is the result which might lead to piston scoring. It is better off shutting it down and having it plugged in to a coolant heater which is a common practice used for gasoline vehicles in Canada.

With the cost of fuel rising with no end in sight, diesel engine is a good alternative to gasoline engines that must be considered. Knowing the basic diesel engine maintenance is essential if you want to save money in vehicle operation and cost.

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