Top 5 Problems with Diesel Truck Engines

Hey, friends. It's Len here from 1A Auto. Today, we want to do a quick video for you on diesel engines. Let's get into it.

Okay, friends. So one of the first things I always like to talk about in any of my problems videos is a safety issue. With that said, with diesel engines, as with almost any engine, they're going to have issues. For this one, it's actually diesel runaway. Now, when this diesel runaway occurs, it's going to be something along the lines of your engine is going to start revving extremely high, which diesel engines, generally speaking, don't want to do. And also when it happens, you're going to notice that even if you turn off your key, the engine just doesn't want to turn off. Now, a symptom of when this runaway condition is going to happen is when your vehicle or your engine is actually pretty much running out of control at an extremely high RPM. Diesel engines don't like to run at high RPMs. They're not meant for that.

Now, since diesel engines are considered a compression ignition engine, basically what that comes down to is they can kind of accept a lot of different types of fuels and combust and, of course, make the engine continue to run. With that said, if there's any type of failure where there's an engine oil leak or any other type of fluid leak, or even a mechanical failure, it can actually cause this condition where the engine just won't turn off and it keeps continuing to run on its own. Now, if this were to happen and you couldn't turn off the engine because it kept going and going and going, that's going to obviously become an issue. Over time, the RPMs are going to continue to rise and rise and rise. That's also going to be an issue. Diesel engines, like I said, do not like to run at high RPMs. They're meant to run at low RPMs. With that said, the valves that are above the pistons inside of your cylinder and everything, they have little compression springs on them, and they're kind of, you know, gauged so the valves open and close to properly time your engine. Those springs, they aren't intended to go boop, boop, boop, boop, boop, boop, they're more like [vocalization]. So, with the high RPMs and boop, boop, boop, boop, they wear out very fast. At some point, they're going to mechanically fail and, of course, the valve isn't going to do what it's supposed to do. Whether it gets stuck completely open or completely stuck shut, it's going to cause an issue for the running of the vehicle. As this is happening as well, the piston is still continuing to go up and down, even though that valve isn't working as it should, because the crankshaft is still spinning due to the rest of the cylinders.

When this happens, if the piston comes up and your valve stem is sticking down, bang, it's going to damage that valve and either knock it way up and into the engine or it could wedge it in or it can go in between your piston and the block itself, and obviously, seize up the engine. If this is happening and it just started, the first thing that I would want to do is, of course, to get my vehicle into a safe location away from people and objects that might cost a lot of money. And obviously, your life is worth more than any engine involved. So, if you feel as though you're in jeopardy, don't do this. But what you could do, pull over, park as fast as possible, right? Your engine is going to be revving. If you have a manual transmission, what you could try to do is keep your foot on the brake, put your vehicle in maybe fourth or sixth gear, depending on how many gears you have, you know, if you're driving a tractor or something, it's going to be different, but anyway, depending on how many gears you have, and then just release that clutch real quick, and hopefully, that'll stall out the engine. Sigh of relief.

If you don't have a manual transmission, obviously, you can't necessarily do that. So, you're gonna have to try to think of a different way to stall out the engine. Like I said, the key isn't working, what are we going to do? You're going to pop the hood. You're going to run right over and you're going to try to kill any air or block out any air that the engine is trying to pull in. So, of course, you'd want to go over to the air filter area. Now, if I was running and I popped the hood, if I wanted to, I could try to just rip this right off of here. I would have to try really hard. Or, of course, you know, you can try to get a socket on there, but who has sockets around? Maybe you could also just come right to here and just take off all these and then lift this up. Once you've done that, if you're lucky enough, more than likely you have a fire extinguisher in, around, or near your vehicle. If you do, and it's a dry chemical, it's the ABC, just like this one right here, it's gonna basically smother out any oxygen that your engine is going to be able to breathe. If it can't breathe, there's no way it can run. Another way that your vehicle may or may not have would be a decompression valve. Some vehicles have them, and it's great because you just twist that valve, it decompresses the engine, and without compression, there's no way your diesel is gonna run. Now that the engine's off, you'd want to let it cool and then continue with your diagnosing because obviously, you don't want this issue to happen again.

The next thing I want to talk about on these engines is not necessarily an engine problem, it's more of like a user problem. But it has to do with diesel engines and it is common. It basically comes down to engine lubrication. There's a lot of questions on which oil should I use, which one's better, synthetic, non-synthetic, you know, multi-weight, single-weight, and it all basically just comes down to this right here. If you were to look inside your owner's manual for whatever vehicle it is you're driving, whether it's a heavy-duty truck, a tractor, a diesel truck, probably even a locomotive, who knows, it's probably gonna tell you exactly what type of oil that the manufacturer recommends. It'll also tell you probably a recommendation for certain temperatures, different altitudes. There's a lot of different things that can affect this. One of the common things you're probably gonna notice when this situation happens is you're probably gonna notice your vehicle has a hard time starting and that's due to having improper oil viscosity. When you have the wrong oil viscosity, it may allow air to get into the hydraulic system, which could affect the fuel injection unit causing basically like a milky foam. And then, in which case, it's not exactly getting the amount of pressure that it should be and the fuel injection unit isn't going to be pumping out the amount of fuel that it thinks it should be. Now, fixes for this would be, of course, to make sure you're using the right oil, and you'll know that by reading this book.

The next thing I want to talk about on diesel engines is the glow plugs. And they're definitely a wear item and they tend to go bad. Let's talk about it. Now, diesel engines use glow plugs to heat up the air prior to starting the engine. The reason for that is because as that piston's coming up, it's creating a lot of pressure, creating heat, and then that's where the combustion happens on a diesel engine. If you don't have enough heat and maybe it's a super cold day, maybe it's wintertime, maybe you live in the Arctic, wherever the case may be, you need to have an initial amount of heat inside that engine. It's just going to help it turn over. If you don't, you're going to notice your engine doesn't seem like it wants to turn over, or it's going to turn over very slowly. Now, once the engine's started, they kind of just turn off and they take a little nap until the next time you have to start up the vehicle again, which is great. Now, glow plugs have a little heater element inside of them. So, basically, it comes in between two prongs, like that, and jumps over. When electrical current goes through one side, it's supposed to go over to here and then complete the circuit. This circuit right here or the element is supposed to heat up as electricity goes through. And that, of course, warms up the engine ahead of time like I was saying before. Well, that element being a very small material, kind of just breaks down over time. Think about maybe like the element on the inside of a toaster. If you were to look inside the toaster with it on, you're going to see them glowing red, same thing. Now, like I said, as this continues to happen, you're probably going to notice that your engine is having a hard time starting. And as the issues continue to move along, maybe one glow plug's bad or even several, the engines can have an even harder time starting. In which case, it only really makes sense, if you're having an issue, have it checked out and get those glow plugs replaced.

Now, the next thing I want to talk about on these vehicles is black smoke. We've all been behind one of these trucks, maybe it's sitting at a red light, the light turns green, it takes off, and you get that big billow of black smoke and the nasty sulfur smell. Let's talk about it. Now, let's talk about why this happens. Overall, it's because you have an improper fuel to air ratio inside the engine. More than likely, your vehicle is running a little bit too rich. Let's go over some of the reasons why this might happen under the hood. Okay. So, if we come right up front here, you have your air filter. Yeah, you could open it up and take a peek or maybe you have one of these and this just makes it easier. If your little bubble is in the green, you're looking all right. That means you're getting plenty of air flow. If it makes its way all the way down to the red, that means that you have a major issue and you're pretty much choking out your engine and this could cause the problem. Some of the other things could be possibly a clogged fuel injector. It could even be your injector pump for the fuel. It could also be your EGR valve is clogged up maybe with carbon or something like that, super common. Or it could also even be your turbocharger if you have a turbo engine.

Now, the next thing I want to talk about on diesel engines is the fuel injection pump. When they go bad and they more than likely will, there's going to be a couple symptoms that you're probably going to notice. You're going to be able to pop your hood and you'll see your engine kind of shaking around. It's not running properly. It probably has a misfire of some sort. Other things that you may notice, you're sitting in the vehicle, you go to step on that gas pedal and you just don't have the acceleration that maybe you once had. Other things that you're probably gonna notice is smoky exhaust, you know, smoke coming out the tailpipe. We've already talked about that, or even you go to start up the vehicle and it just doesn't want to start, it's having a little bit of trouble. Or even difficulty starting. Maybe you're sitting inside the vehicle, you go to start it, and it's a hard crank. [vocalization]

Okay, friends. So, we tried to make a nice educational video for you about problems with diesel engines. If you learned a little something or you have something to say, feel free to leave it in the comments section below, I'd love to hear from you. If you like the video, smash in that like button for me. And as always, feel free to subscribe and ring the bell, that way there, you can be kept up with all of our latest content.

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