Five Signs Your Diesel’s Glow Plugs Are Going Bad

Some diesel vehicles have a dashboard warning light, usually the check engine light, that warns you about glow plug issues. But not all do. MDP Diesel & Auto knows that problems with your diesel engine can be intimidating and might mean you can’t do what you need to do. Here are other ways to recognize possible issues with your diesel’s glow plugs.

The Engine Idles Roughly

If only one or two glow plugs are going bad or have failed, you might find that the engine seems to idle more roughly. The engine might be a little louder than usual and you’re more likely to feel the vehicle vibrating. This is a sign that something in the engine isn’t working properly and needs to be checked out.

The Engine Is Misfiring

Your vehicle’s diesel engine is a little different from a gas engine in that it requires much more compression and heat to get the combustion it needs to keep running. If fuel and heat aren’t synced up properly, the engine misfires. The engine is too cool to run properly and over time, this can cause damage to the engine.

It’s Hard To Start The Vehicle

Diesel engines rely on glow plugs to offer up the heat they need to get started. So if the glow plugs are going bad, it’s going to be a lot more difficult to get the vehicle started. You might even think the problem is something else, like the battery, until the glow plugs fail completely or you replace them.

Fuel Efficiency Is Lower

Lots of factors can affect fuel efficiency and glow plugs aren’t always the biggest impacting factor. But if you’re seeing some of these other signs and your fuel efficiency is a lot lower than usual, then the glow plugs may be to blame. 

You’re Seeing White Or Black Smoke In The Exhaust

Both black and white smoke pouring out of the exhaust are not great signs. White smoke occurs when there isn’t enough heat in the engine to properly combust the fuel. Those unburnt fuel particles then exit the engine via the exhaust and smell like diesel fuel. Black smoke is often a result of the air and fuel mix being off, typically with too much fuel. Glow plug issues make both of these issues worse.



Think you’ve got an issue with the glow plugs in your diesel engine? Give us a call at MDP Diesel & Auto in Jackson, MI. We can test the glow plugs and look at other possible issues and let you know what your diesel needs to run properly.