How to Replace Glow Plugs on a Diesel Engine

Written by bryan cowing | 13/05/2017
How to Replace Glow Plugs on a Diesel Engine
Diesel engines use glow plugs, which require replacement from time to time. (detail of diesel engine image by Petr Gnuskin from

If you are having problems starting your diesel engine, you may need to replace the glow plugs. The glow plugs are an important part of the engine. They heat the air inside the cylinder, which causes the diesel fuel to explode when it is injected. This explosion is what moves the piston. If glow plugs malfunction, your motor may not even start. Fortunately, replacing the glow plugs in your diesel engine is straightforward.

Open the bonnet.

Look at the centre of the engine. You should see the glow plugs lined up diagonally. They are silver in colour and sometimes have a pink or white ceramic top.

Place your socket wrench over the first glow plug you would like to remove.

Turn the socket wrench in a counterclockwise motion to loosen it.

Pull the glow plug up and out of the engine with your hand.

Put a new glow plug in the empty glow plug chamber.

Place your socket wrench over the new glow plug.

Tighten the glow plug by turning your socket wrench in a clockwise motion. Make sure that you push the socket wrench all the way down to the bottom of the glow plug so that you reach the retaining nut. Re-install the connection wire.

Repeat the preceding steps for the remaining glow plugs.

Things you need

  • New glow plugs
  • Deep socket wrench set

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