Do Diesels Have Spark Plugs?

Everybody knows diesel engines are different from gasoline engines in the fuel they run, but it can be easy to overlook the differences beyond that. Despite doing practically the same thing, diesel and gasoline engines operate in wildly different ways.

What Are Spark Plugs?

Spark plugs are components used within internal combustion engines to ignite the air-fuel mix in each cylinder. They create an arc that jumps from one electrode to another, and in turn, ignites what’s within the cylinder. 

Do Diesel Vehicles Have Spark Plugs?

One of the biggest differences is the way they create combustion. While gasoline engines use spark plugs to ignite the air-fuel mixture in the cylinders, diesel engines do not. Instead, they use the compression of the cylinder itself to ignite the diesel. 

This doesn’t mean that diesel engines are unassisted in combustion though. Diesels use a system of glow plugs to maintain a high enough temperature within the cylinder to allow for efficient combustion. 

In a base-level way, spark plugs are glow plugs are actually very similar. Both systems use electricity to aid in ignition. There are some major differences, however. Spark plugs do the work of ignition themselves, creating an arc of electricity used to ignite the air and fuel. On the other hand, diesel glow plugs simply heat up the cylinder to an adequate temperature for proper combustion. 

What Are Glow Plugs?

As stated before, glow plugs are located within each cylinder to ensure to temperature is hot enough for diesel combustion. However, not all diesel engines have spark plugs.

Glow plug on white background
陳金棠, Public domain, via Wikimedia Commons

While all their gasoline counterparts require spark plugs for ignitions, bigger diesel engines do not need glow plugs. They’re only necessary on smaller engines, where the smaller cylinders struggle to maintain proper operating temperature.

How Often Should I Replace My Glow Plugs?

Like any engine component, glow plugs will eventually need to be replaced as well. A general rule of thumb is that your plugs should be replaced above every 100,000 miles. 

Glow plugs that are in need of replacement can cause some easily noticeable symptoms, such as:

  • Rough idle
  • Hard starting
  • Smoke from exhaust
  • Misfires
  • Decreased power
  • Decreased fuel efficiency

Diesel Service at Scott’s U-Save

If you’re searching for trustworthy diesel service? Our expert technicians at Scott’s U-Save will ensure your diesel is running at its best and is serviced with the highest quality possible!

Call or schedule online today at any of our locations in the greater Chicagoland area. 

Schedule An Appointment

Whether you're shopping for tires, looking to lift your truck, or need auto repair, Scott's U-Save is here to serve you! Schedule an appointment online or call today!

Get In Touch