Glow plugs are like spark plugs, but for diesel engines. How long do glow plugs last, what kind do you need, and how can you even get a look at them? Find out below.
Glow Plugs vs Spark Plugs
Instead of creating a spark that burns and ignites, diesel engines use glow plugs that glow red hot increasing compression during the ignition process.
How Does a Glow Plug Work?
In essence, glow plugs start the vehicle’s engine. These plugs get hot, which is why they "glow." This heat ultimately creates the combustion needed to get the engine powered and running.
They are, therefore, an essential component of the engine and you need them in perfect working order. If the glow plugs are malfunctioning, your engine might not start at all.
There's a glow plug for each cylinder in your diesel car. It’s a piece of metal with a shape a little similar to a pencil. There’s a heating element on the tip.
When you turn the key in an older diesel engine, you shouldn’t turn it all the way. Instead, partially turn until the “wait to start” light on the dash goes off. This indicates the heating element has reached a temperature at which it can start the engine.
Signs of Bad Glow Plugs
- Trouble starting
- Engine misfiring
- Slow acceleration
- Decrease in fuel efficiency
If you notice problems like these, do a visual inspection of the glow plugs to see if they need to be replaced. Replace them if the glow plugs are blackened at all or visibly misshapen in any way.
If they look fine but the problems persist, you might still want to replace the glow plugs to see if this resolves the issue.
How Often Do Glow Plugs Need to Be Replaced?
Glow plugs usually run well for about 100,000 miles, though they may burn out more quickly or last a little longer. Even if your glow plugs look fine and everything's working, you should still replace them after 100,000 miles.
Once your glow plugs start malfunctioning, you’re already putting stress on your engine, so when your vehicle hits that mile mark, replace your glow plugs instead of waiting for a problem. If you DIY the job, this won’t be too expensive, unlike the other damage you might accidentally cause.
Because you replace all glow plugs at once, rather than one or two at a time, they are sold as an entire set. It is possible to purchase a single glow plug but probably more affordable to buy an entire set, as buying one at a time as needed can be more expensive in the long run.
The number of glow plugs you will need depends on the size of the engine. Your vehicle may need up to 10 plugs. It all depends on how many cylinders your vehicle has.
Depending on the type, size, and material used for the glow plugs, you will spend $100 to $250 USD for a standard set of glow plugs. More high-end plugs will cost more and some plugs will cost less.
You can find glow plugs on sale everywhere, from brick-and-mortar retail stores to online retailers. This gives you the opportunity to shop around and look for the most suitable glow plugs for your vehicle.
Should I Replace All Glow Plugs?
When one glow plug starts to go bad you should replace all of your glow plugs. Only one may be malfunctioning at the current moment but since low plugs tend to go bad right around the same time, it's better to replace them all.
You don’t want to spend two weeks replacing each and every glow plug one at a time as they all go bad when you could just as easily replace the entire set and start fresh.
Don’t make things harder on yourself. Whenever you can, replace the entire set of plugs and get it all done at once. You know what to fink about it against for a whole year!
Where Are Glow Plugs Located?
If you're going to examine and replace your glow plugs, you need to know where the heck they are. Trying to pull things apart and guess where they are will only do your vehicle a whole lot of harm. The good news is, glow plugs are located in the same place on all types of diesel vehicle engines: they’re in the cylinders.
There is a glow plug within each cylinder of your vehicle. Each one is directly connected to the engine control unit. A microprocessor analyzes the engine temperature. This is what turns the glow plugs on and off. If you can find the cylinders, you can find the glow plugs inside of them.
To find the glow plugs, look at the cylinder heads of the vehicle. You may see the top of the glow plugs sticking out of the cylinders. The wire is another good giveaway that you're in the right area of the engine. This is a power supply for the 12 volts of energy it takes to get those glow plugs heated up and working.
Before you attempt to remove and replace glow plugs, disconnect this power supply and move the wire out of your way. Glow plugs can be removed with a socket and ratchet.
By performing the little maintenance tasks like replacing your glow plugs, changing your oil, and cleaning your filters, you can avoid the need to address much bigger engine problems down the road…and keep getting down the road smoothly in your vehicle!
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