Diesel Engine Questions and Answers - Part 1

At ProSource Diesel, we like our customers to be informed about diesel engines, diesel parts, and how these engines work.

There are a number of diesel terms and diesel engine parts that may not be familiar to new owners or those who are only familiar with gas engines. That’s why we’ve devised a list of common diesel engine questions and answers to help you get up to speed.

Q: How many spark plugs does a diesel engine have?

A: Unlike gas engines, diesel engines don’t use spark plugs for combustion. Instead, diesel engines rely on compression to quickly raise air temperature to ignite combustion when the diesel fuel is introduced to the hot, high-pressure air.

A similar diesel part to a spark plug is a glow plug. These are heating devices used to help diesel engines get up to proper combustion temperature in cold weather. In general, when referring to the diesel engines made by Duramax, Powerstroke and Cummins, a diesel engine has 8 glow plugs.

On an additional note, all 5.9 and 6.7 Cummins use a grid heater which is a different method of warming the air in the combustion chamber enabling the fuel to ignite.

Q: How does a diesel engine work?

A: Diesel engines use internal combustion just like gas engines, however, they have a compression-ignited injection system vs. the spark-ignited system used by gas engines. In a diesel engine, fuel is injected into the combustion chamber and is ignited by hot compressed air.

Diesel engines have higher efficiency than gas engines in burning fuel, but they also create more pollution. A number of after-treatment parts are installed on modern diesel engines to reduce exhaust pollution.

Q: How long do diesel engines last?

A: A well-maintained diesel engine can run for as many as 1,500,000 miles before needing serious work. This is in comparison to gas engines that usually need major work after 200,000 to 300,000 miles, despite regular maintenance.

The reason for the longevity and durability of diesel engines is due to the design, the type of fuel, and the application. Diesel engines are gear-driven, which means they can be easily fixed and not lose timing.

Diesel vehicles are constructed with heavy-duty parts that can withstand all the power of a diesel engine. Diesel engines are also self-cooling, which decreases their chances of overheating. The method of spontaneous combustion is also conducive to a longer-lasting engine.

Q: How many glow plugs does a diesel have?

A: A diesel engine, like those made by Powerstroke, Duramax and Cummins, has 8 glow plugs. One is located in each cylinder to warm the air in cold temperatures. Not all diesel engines have glow plugs as they are not strictly necessary to the operation of a diesel engine.

Some, like the Cummins 5.9 and 6.7 use a grid heater to warm the air in the combustion chamber.

Glow plugs are a starting aid that many modern diesel engines are equipped with.

Q: What is blow-by on a diesel?

A: Blow-by is a term that can be used across either diesel or gas engines. For a diesel engine, blow-by happens when the air and fuel pressure in the cylinder bore is more than the oil pan pressure. This causes gas to leak past the piston rings and into the crankcase.

Some blow-by is normal, but on modern diesel engines pressure sensors compensate for erratic pressure in the cylinder. Blow-by is now more likely to mean that rings are worn, destroyed, or sticking to the cylinder walls.

Q: What causes white smoke from diesel engines when accelerating?

A: White smoke happens when diesel fuel isn’t getting hot enough to burn properly. This causes it to come out through the exhaust intact. Diesel fuel that isn’t getting hot enough might be caused by a clogged fuel filter, incorrect injection timing, or low cylinder compression.

Another reason for white smoke is water getting into the diesel fuel and then entering the combustion area. This commonly occurs with bad head gaskets or a cracked cylinder head or block.

Q: What is the best diesel engine?

A: The title of ” best diesel engine” is always debatable among diesel enthusiasts and experts. When it comes to diesel engines in modern pickup trucks, the best diesel engine list might look a bit like this:

Q: How does a diesel engine start

A: Unlike gas engines, diesel engines use a spontaneous combustion process. When you turn the ignition key, a process begins where the fuel is injected into the hot pressurized air of the combustion chamber.

This only takes about 1.5 seconds on modern engines in moderate temperatures. In lower temperatures, glow plugs are used to preheat the chamber.

Q: What does it mean to bulletproof a diesel engine

A: The term bulletproof is not exclusive to diesel engines or diesel enthusiasts. Simply put, a bulletproof engine is one with extreme reliability.

The interesting thing is that the term gained popularity according to Google searches in 2009, which happens to be the same time that parts manufacturer BulletProof Diesel was founded.

The process of bulletproofing an engine generally means fixing weaknesses in a stock engine to give it increased reliability. For example, bulletproofing the Ford 6.0-liter diesel meant replacing the factory oil cooler with an external one and then updating the internal EGR coolers.

Many Ford 6.0-liter owners also replace head gaskets and head studs as a preventative measure to further bulletproof the engine.

Rely on ProSource Diesel for Powerstroke parts, Cummins parts, Duramax parts, and a wide range of diesel performance parts to upgrade and repair your rig. ProSource is where the diesel repair shops shop for diesel truck parts.