What is the Glow Plugs all about?
Diesel fuel is self-igniting under pressure. However, very cold temperatures can prevent ignition. This is where glow plugs come into play. Unlike spark plugs, which create an arc of electricity, glow plugs preheat the cylinder so the fuel can ignite more easily. The electrode heats up, glowing like the filament in an incandescent light bulb, and provides the necessary assistance to ignite the diesel fuel.
Keep in mind:
- Removing glow plugs from many vehicles can be difficult and labor intensive.
How it's done:
- The vehicle battery is disconnected
- The defective glow plugs are removed
- The new glow plugs are installed and wiring is connected
- The battery is reconnected
- The glow plug system is checked for proper operation and the vehicle is road tested for proper operation
The glow plugs will eventually fail and require replacement, though not at any specific interval. It may be necessary to replace the wiring harness, the glow plugs, and the relay that controls the glow plugs. In some vehicles, the relay actually fails more often than the glow plugs. If you suspect a problem with the glow plugs on your diesel engine, have one of our expert mechanics inspect and replace them as necessary.
What common symptoms indicate you may need to replace the Glow Plugs?
- Hard/slow starting in cold weather
- Not starting in cold weather (barring battery or other equipment failure)
- More smoke than usual when starting (exhaust)
- Misfire on a cylinder until the fuel warms up enough
How important is this service?
Glow plug replacement isn’t like replacing spark plugs, and some diesel owners can go for 100,000 miles or more without changing them. The relays fail more often than the plug, which is another reason it is very important to have the problem diagnosed by one of our expert diesel mechanics. This will ensure that you’re fixing the underlying problem, rather than just addressing symptoms, saving you time, money and headaches.