Trucks & SUVs

The Most Common Diesel Truck Problems

There are plenty of perks to owning a diesel-powered truck. They often deliver higher fuel-efficiency ratings, are able to tow more, and allegedly last longer than gas-powered engines do. That’s not to say you shouldn’t expect some problems along the way. So, why not familiarize yourself with some of the most common diesel truck problems

2021 Ram 1500 Limited EcoDiesel parked
2021 Ram 1500 Limited EcoDiesel | Ram

A runaway diesel engine can be pretty dangerous

Now, this isn’t the most common diesel truck problem, but it is worth keeping in mind because it could result in your truck catching fire. If you haven’t heard of a runaway diesel engine, it’s pretty much exactly what it sounds like. An engine that just won’t stop. Age and wear are often the most common cause but a runaway diesel engine can also be caused by things like sticky pumps that meter too much fuel, oil seal failures, overfilling the truck’s crankcase, damaged internal fuel pipes, faulty fuel linkages, among other things. 

Fortunately, CarThrottle reports that runaway diesel engines aren’t nearly as common as they used to be. “Most Electronic Control Modules (ECMs) can meter the fuel more accurately and sensors warn the ECM and allow it to prevent things like this from happening,” CarThrottle explains. But if you are faced with this situation? CarThrottle recommends smothering your truck’s engine with a CO2 extinguisher. After you get the engine to stop, it’s time to call in a tow truck.

RELATED: What’s the Difference Between Gas and Diesel Truck Maintenance?

Prepare to replace your diesel truck’s glow plugs 

Unlike gas-powered trucks, some diesel trucks come outfitted with glow plugs rather than spark plugs. Essentially, glow plugs are designed to preheat and warm up your engine’s cylinders so that diesel combustion can happen more easily. According to Your Mechanic, when glow plugs have an issue, it could cause problems with the driveability of your truck. 

Your Mechanic reports that engine misfires are one of the first signs that a truck’s glow plugs are facing some serious problems. Hard starting can also point to an issue with your truck’s glow plugs, as can black smoke coming from your truck’s exhaust. The bad news is that replacing glow plugs can be difficult and labor-intensive so you’re going to want to keep an eye out for this common diesel truck problem. The good news is that not all diesel trucks come outfitted with glow plugs. Take, for instance, Cummins, which forgoes the glow plug setup in favor of a single heater grid located in the intake of the engine.

RELATED: What Makes a Diesel Truck Different From a Gasoline Truck?

Engine oil oxidation is a problem for diesel trucks

Unfortunately, runaway diesel engines and faulty glow plugs aren’t the only problems diesel trucks face. According to RC Auto Specialists, oxidized oil can also lead to some issues. If you let your diesel truck sit in one place for too long, don’t drive it often enough, or put it in storage for long periods of time, you may have problems with oil oxidation. But what does that actually mean? Well, RC Auto Specialists explains that once air gets into the oil it can create bubbles that interfere with proper lubrication. Unfortunately, this could result in a damaged engine.

RELATED: Does the Toyota Tacoma or Tundra Come With a Diesel Engine?

Black exhaust could signify a problem with your diesel truck

We’ve all passed by a truck as its exhaust spits out thick, black exhaust fumes. It’s gross, I know. It’s also one of the most common diesel truck problems. And according to Bell Performance, can point to things like faulty injectors, a defective injector pump, a bad air filter, a clogged EGR valve, or even a bad turbocharger. Experience this problem, and you can expect your diesel truck to be less fuel-efficient than it usually is.

Should you opt for a gas-powered truck instead?

While diesel trucks are bound to experience some of these common problems, gas-powered trucks do have their own problems to contend with. So, while these common diesel truck problems might give you pause, they really shouldn’t. Instead, they should give you a heads up on what to expect.