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How Do You Know When It’s Time to Replace Your Glow Plugs?

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Is it hard to start your diesel pickup when it’s cold outside? If so, it may be time to replace your glow plugs.

A technician using repair tools to fix a car engine, with the caption “How do you know when it’s time to replace your glow plugs?”

What Are Glow Plugs?

Glow plugs are a heating element that is part of the ignition process in diesel engines. Located in each of the engines’ cylinders, glow plugs use battery voltage to generate heat. It is this heat that helps to ignite the diesel fuel during startup.  If your diesel engine lacks this additional heat it could result in hard starting. *Hard starting is when the engine cranks over but doesn’t start.

Diesel engines cannot start “cold.” You need to allow a little time for the glow plugs to warm before you fully engage the ignition system. You will typically have a dash light that indicates when it is safe to fully turn the ignition over. Cranking the engine while the glow plugs are warming up is a BIG no-no. Especially in winter months when things are extra cold.

How Long Do Glow Plugs Last?

The average life of a glow plug on a diesel engine is roughly 100,000 miles. So, it is not something you should have to worry about very often. However, they can fail before then, especially if you hard start frequently or use a lower quality glow plug than recommended in your pickup.

How Do You Know When It’s Time to Replace the Glow Plugs?

Often, the glow plugs on a diesel engine are overlooked, until they are malfunctioning. As a diesel pickup owner, it is important that you understand the signs of failing glow plugs and that you act quickly to get them replaced. The longer you wait to replace faulty glow plugs, the more damage you will have to deal with.

If a glow plug fails, your pickups’ combustion chamber will not receive the heat that it needs to ignite. On warmer days, you may be able to achieve ignition after multiple startup attempts. But, in the colder winter temperatures, it is very unlikely that your engine will ignite at all if you have faulty glow plugs.

There are other indications that you have glow plug trouble on your hands beyond your pickup failing to start when it’s cold. Learning what these signs are and acting accordingly can help you make sure you don’t wind up stranded.

Here are six signs that it is time to replace your glow plugs:

  • Decreased fuel efficiency
  • Difficult acceleration
  • Engine misfire
  • Hard starts or no start at all, especially in cold weather
  • Loss of power
  • More smoke emitted from the vehicle than normal

Driving your pickup under these conditions can be unsafe and possibly cause further, more expensive, damage.

When the time comes, it is best to have a professional change out the glow plugs, as it is a complex process. We can help. Gem State Diesel & Turbo Repair has a reputation for superior diesel pickup repair and service in the Boise area. Schedule an appointment online or call us at 208-288-5555.