10 Heavy Truck Diagnostics Terms You Should Know
There are hundreds of millions of drivers around the world, and all of them have vehicles that need maintenance from time to time. But there are far less mechanics than there are drivers, so unfortunately, the majority of drivers have a high likelihood of encountering a problem at some point that they can’t identify or explain.
“It wiggles, you know? Really fast, when I go fast.”
“There’s kind of a, I don’t know, chongakongakonk sound. Is that bad?”
“It feels like the tires are loud, and when I try to turn, there’s a…a shriek?”
While all of those may describe legitimately terrible trouble under your truck’s hood, they don’t really give a mechanic much more than a vague idea of what the problem might be. And that’s bad news for you, because if the technician fixing your heavy truck has to spend a couple of hours finding out what’s really going on – especially if your sound effects and explanation were the cause of the misunderstanding – your costs for labour are going to get much higher.
Here are some of the top ten truck diagnostics terms that mechanics and technicians use all the time. Remember them for the next time you feel something off while you’re driving – it could save you serious headache!
1. Backfire: Often heard about in pop culture (and much less common nowadays than they used to be), a backfire is a gunshot-like sound that comes from the engine or tailpipe. They are caused by unburnt fuel in the exhaust system igniting and rapidly combusting, and are known to cause a loss of power and motion. See a video clip of an engine backfire here.
2. Bottoming: This refers to excessive noise or harsh vibrations that are often felt through the steering wheel or passenger area, often when going over bumps. First place to look for the problem? The shock absorbers and other parts of the shock system, which help mitigate road imperfections while driving.
3. Bucking: Does your engine hesitate or “lurch”, as the transmission slips while trying to change gears? Then you’re familiar with bucking. The most likely cause is in the fuel line, as the engine isn’t getting the fuel that it needs to maintain power.
4. Dieseling: If you turn off your engine, but the truck continues to burn fuel and run for a moment afterwards, that is known as dieseling – because it’s due to an air-fuel mixture combusting in the cylinder without a spark, like in a diesel engine. It can signify timing issues, temperature moderation problems, or any of several other similar factors.
5. Hesitation: When you accelerate and feel a sudden loss of power, that’s hesitation. It can be traced back to low fuel pressure, slowed ignition timing, poor quality fuel, low voltages/weak sparks…the list goes on.
6. Knocking: Also called “detonation”, this is a rapid rattling noise that can be heard upon acceleration, and is often caused by fuel burning unevenly instead of in one smooth, continuous action.
7. Misfire: A category of hesitation, these happen when fuel in one or more of the engine’s cylinders fails to ignite properly and interrupts the flow of power.
8. Shimmy: A pronounced side-to-side motion that transmits from the tires through the steering wheel. While the details can change for each case, the main culprit behind it all is an imbalance of some type – in the tires, in the treads, in the brake rotors, etc. When they are not symmetrical, the mismatch is very noticeable.
9. Sluggish: If you’ve ever floored the gas and the car barely made its way down the road, or felt very jumpy while accelerating, you’ve encountered a sluggish engine. It means it’s just not delivering the horsepower that it should be, based on your power input.
10. Surge: Like the opposite of a hesitation, a surge is a sudden (usually upward) change in a vehicle’s engine speed. Like a lot of these problems, inconsistent fuel delivery and pressure is usually to blame.
Remember these terms for the next time you’re bringing your vehicle in for our money-saving preventative maintenance or repair, and it will help the mechanic pinpoint the problem faster – getting you back on the road more quickly, and making sure the root cause is fixed.
1/26/2022 03:57:49 pm
It's interesting when you said that engine problems may cause backfire. My best friend told me last night that he is hoping to find a service because he's not able to use his diesel-powered car because of a brakes problem, then he asked if I had any idea what is the best option to do. Thanks to this helpful article, I'll be sure to tell him that he can consult a well-known diesel mechanic in town as they can help him with his concerns.
2/24/2022 10:03:34 pm
It got me when you said that backfires are gunshot-like sounds caused by unburnt fuel. This is helpful because our truck has an engine backfire and we need to have it fixed as we are going on a road trip next weekend. We are hoping to find diesel truck repair services tomorrow morning to have it serviced and inspected for a safe and comfortable ride.
7/18/2022 03:48:47 am
Thank you for letting me know that dieseling is when the truck continues to burn fuel after turning off the engine. My friend told me that his vehicle is consuming excessive fuel. I should advise him to look for an expert to perform diesel diagnostics and figure out the real problem.
Thanks for helping me understand that the knocking sound is called the detonation which would be caused by fuel burning unevenly. I wonder if that is the issue with the vehicle of my best friend, because I heard that when I visited him earlier. It would be a good idea if he finds a professional mobile trailer repair service to check his vehicle as well as the trailer he has, so he can be safe for the trip he plans to go on this coming August.
8/22/2022 12:31:34 pm
My brother and I want to start a trucking business together next year, so we're eager to learn more about trucking maintenance. It's great that you explained how to understand heavy trucks and their common repair needs, so we'll read this very carefully. Thanks for the insight on identifying a faulty heavy truck and its source.
9/9/2022 09:11:50 am
I want to make sure that I get my truck fixed up properly. It makes sense that I would want to work with a professional to ensure that I get the correct repairs done. That seems like a good way to ensure that everything ends up working out properly.
11/8/2022 12:30:59 am
It's interesting to know that the engine is not getting the right amount of fuel it needs when it is bucking. I can imagine how there are so many different issues that one can have that would need truck repair services. For me, the best thing to do is to clearly explain what happened to a professional so that they can get to the root cause of the issue.
11/14/2022 12:50:12 pm
Thank you for explaining that you may have problems if your truck is sluggish when making its way down the road. My brother mentioned how this started happening with his truck last week. I'll be sure to talk to him about this and see if he can get it fixed before his next haul.
1/3/2023 03:44:24 am
Thank you for mentioning that dieseling occurs when a truck stops burning fuel but keeps running for a short period of time after the engine is turned off. For his construction site, my cousin wants to hire heavy-duty transportation. I'll advise him to familiarise himself with the words given on your website.
3/1/2023 04:31:11 pm
I appreciate that you explained that bucking could be experienced by having a concern when switching gears or transmission. My brother informed me a couple of days ago that he and his business companion were looking for a trailer service that could offer a trailer repair because of an engine malfunction and a lack of maintenance. He asked if I had any thoughts on what would be the best option for repair. I love this informative article. I'll tell him that he can consult a trusted professional trailer repair service as they can provide details about the repair process and preventative actions.
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