How to Replace Glow Plugs on Vehicles

by Contributing WriterUpdated June 12, 2017

The glow plugs in a Vehicles work the same as glow plugs in any diesel engine. However, their exact location may differ according to the Vehicles. Because engine size and design ultimately determine where the glow plugs are fitted, you may need the particular Vehicles service manual to help you locate the plugs.

Under The Hood:

 How to Replace Glow Plugs on a Jeep Liberty CRD

Open the hood of your Liberty and locate the negative battery cable on the top of the battery. The battery sits on the driver's side of the engine compartment, right behind the driver's-side headlight assembly. Loosen the clamp bolt on the cable end with a wrench and remove the cable from the battery, isolating it from the terminals while you are working.

Locate the glow plug in question on the side of the cylinder head. The cylinder head is at the top of the engine assembly, running front to back along the engine block. Grasp the wire at the top of the glow plug at the boot and pull it straight off the plug. Lay the wire aside.

Place a socket over the glow plug, attach a ratchet, and turn the plug counterclockwise. Pull the plug out of the cylinder and discard it.

Carefully insert the new glow plug in the cylinder head. Tighten the glow plug to 110 inch-pounds with a torque wrench. Snap the wiring harness connector onto the top of the glow plug. Repeat the process for the remaining glow plugs until you have replaced all that are defective.

Install the negative battery cable on the negative battery terminal. Tighten the clamp bolt with a wrench, making sure it is secure. Do not over-tighten it or you may damage the cable end or terminal. Close the hood of your Jeep.

Items you will need

  • Wrench set

  • Socket set

  • Ratchet

 How to Replace Glow Plugs in a Tractor

Remove the glow plug wires running to one of the cylinders. While all of the glow plugs should be replaced, you should work on only one plug at a time. It generally does not matter which plug you start with. To remove the plug wire, pull up on it. You may need to twist or rotate it back and forth gently and pull up on it at the same time to remove it.

Connect the glow plug socket and socket extension together. Then, connect the extension to the socket wrench. Slide the glow plug socket down into the plug well (underneath where the the plug wire was that you removed from the engine). Fit the socket over the plug and turn it counterclockwise to remove it. Pull the plug out of the engine. Remove the plug from the socket and insert a new plug.

Slide the socket back down into the engine and thread the plug. Be careful when threading. You do not want to cross-thread the plug. Make sure that the plug threads easily for at least 3 turns. Tighten the plug and attach the glow plug wire. Repeat steps 1-8 for all glow plugs on the engine. For each plug wire, there is a glow plug underneath it.

Items you will need

  • Glow plug socket

  • Socket extension

  • Socket wrench

  • New glow plugs

 How to Replace the Glow Plugs on a Diesel F350

Remove one of the plug wires from the engine. It does not matter which plug wire you start with, but you should only work on one plug wire/plug at a time. Pull up on the wire to remove it from the top of the engine.

Connect the glow plug socket to the socket wrench and to socket wrench extension and place the extension and socket down the glow plug well through the top of the engine until you feel the top of the glow plug. Orient the wrench so that the socket "grabs" the top of the glow plug. Turn the wrench counterclockwise to remove the plug. The plug will come out with the glow plug socket.

Place the gap checker between the two electrodes on the new glow plugs. The specific gap on the plugs may differ according to the model year of the F350. There are numbers on the end of the gap tool telling you what the current gap is between the two electrodes. Adjust the gap by using the tool to bend the electrodes either farther apart or closer together.

Lower the glow plug into the engine using the glow plug socket, extension and socket wrench, and turn clockwise to tighten.

Reset the plug wire into the glow plug well.

Items you will need

  • Socket wrench with extension

  • Glow plug socket

  • Gap checking tool

 How do I Replace Glow Plugs in New Holland Tractors?

Remove the glow plugs

Disconnect the negative battery terminal. Disconnect the positive battery terminal. Move the cables away from the battery terminal posts.

Clean around the injectors and glow plugs, removing all dirt, grease, oil, and debris.

Disconnect the fuel lines from the injectors. Disconnect the glow plug wires.

Remove the glow plug, taking care not to drop any dirt or debris into the cylinder. If needed, continue with the other glow plugs. When reinstalling the glow plugs, torque the glow plugs to 11-14.5 ft. lbs. (15-20 Nm).

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