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What are glow plugs and what do they do?

By Kijiji Autos
What are glow plugs and what do they do?

You might hear the term glow plug and immediately think that it's just a fancy name for ""spark plug"", and a mechanic is trying to make your car trouble sound worse than it is. But don't be misled: spark plugs and glow plugs (also spelled ""glowplugs"" or ""glow-plugs"") are actually different. And depending on what kind of car you have, your car may or may not have glow plugs sitting under the hood.

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We’ve gone into more detail about glow plug specifications below:

What is a glow plug exactly?

A glowplug is a thin, hollow metallic device that contains insulating ceramic powder and a heating coil. A single car can have up to 10 glow plugs, as every cylinder requires one.

What does a glow plug do?

A glowplug is used to help ignite a diesel engine. Unlike a spark plug, which is used to ignite a gas engine and power it while it is turned on, a glow plug is only used to help cold-start the diesel engine.

Why are glow plugs important?

You may have heard the myth that diesel engines don’t start in winter, but it’s not exactly true. Diesel fuel can become gelatinous at extremely low temperatures, which can potentially make starting an engine very difficult, but modern diesel engines are capable of starting in even the Winnipegest of winters thanks to technologies like the glow plug. If you’re worried about keeping your car in tip-top shape this winter, check out these winter maintenance tips.

Understanding your glow plugs

You know your glow plugs are working when you start the engine and your glow plug symbol (the yellowish-orange squiggle) lights up for a few seconds. Just like your wipers or brake pads, glow plugs require occasional replacement, usually every 100,000 kilometres or so.

When should I check my glow plugs?

Your glow plug light should only stay on for a few seconds when you start your engine. But if your light comes one while you’re driving, it means that something isn’t working properly. At this point, you have two choices: change the glow plugs yourself or take your car to a mechanic. Even though car technology is becoming increasingly complex, replacing your own glow plugs is still fairly easy.

How to tell if you need to change your glow plug

It’s not too difficult to tell if you have a glow plug problem. Watch out for these three symptoms:

· Difficulty starting the engine

· Poor engine power

· White exhaust smoke

If you feel confident enough to check the glow plugs yourself, you will need a glow plug tester or multimetre.

Step 1: Disconnect your glow plugs.

Step 2: Turn your tester on and make sure it’s set to Ohms or Ω. Touch the black and red leads together. If you get a zero reading, adjust the sensitivity settings until you see a number. Record the value.

Step 3: Touch the negative terminal on your battery with the negative lead.

Step 4: Touch the positive terminal on the glow plug with the positive lead.

Step 5: Now you should have a reading. Subtract the initial reading from this new value. If the reading is not within the suggested range for the glow plug’s specifications, you will need to replace it. If your reading is within the correct resistance range, we suggest taking it to the mechanic.

Glow plugs are integral to a diesel car’s performance. If you’re a first-time car owner, it’s easy to be overwhelmed with knowing how to properly maintain your vehicle. Want more helpful tips and advice on how to take care of your car? Check out this handy advice for first-time car owners. Or if diesel engines are your thing, browse diesel cars for sale on Kijiji Autos!

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