A truck is composed of hundreds of parts with varying lifespans and lengths of service. As it drives more and more miles, these parts are subject to wear and tear. And despite manufacturers' suggested lifespan and regular vehicle inspections, the reality is that breakdowns in the trucking industry happen, and vary with usage, mileage, climates and more. Below are the most common trucking breakdowns that our owner-operators experience, as well as some tips on how to reduce downtime from mechanical failure.
#1 Tires
Tire failures are among the most common truck breakdowns. Tires are also your biggest expense while you're on the road.
Some of the leading causes of tire failure include:
- Overinflation or underinflation
- Misaligned axles
- Road hazards
- Vandalism
- Manufacturer defects
Tire Inflation
Check the tire manufacturer's rating for proper tire pressure.
If you put in too much air pressure, the tire forms an outward curve at the treads. This leads to the treads toward the center wearing faster than the outer treads.
If you underinflate, the outer treads wear out faster.
Many old-school truckers use the "heavy stick test" to check their tire inflation. This is where they strike the tire with a short wooden two-by-four, small baseball bat, or some other "tire thumper". The tire "sings" a certain tone if it's inflated properly when you thump it with the stick.
This could work well if you have what musicians call "perfect pitch".
Even among professional musicians, perfect pitch is very rare. It's better if you use a tire pressure gauge that's calibrated for heavy-duty tires.
Axle Alignment
If your axles are out of alignment it can cause uneven wear on your tires. It also affects how your truck handles on the road. You may need to replace your tires sooner than necessary if you have uneven tread wear from misaligned axles.
During your pre-trip inspection, be sure to check that there's not a problem with the axle alignment. If you find that they're improperly aligned, get the truck serviced right away.
Tread Depth
Your tread depth should not be less than 1/16 of an inch (tread gauges read it as 2/32). Anything below this and you need new tires.
Use a tread depth gauge to measure your tread depth. If you don't have one, you can use the "penny test".
- Insert a standard US penny into the tread groove with President Lincoln's head toward the groove.
- If the treads cover at least part of Lincoln's head, you're in good shape. If his head doesn't go into the groove at all, it's time to replace the tire.
Avoid Inferior Tires
Tires are such a big expense on the road, so it's understandable if you're tempted to go cheap when you need to replace them.
You don't need to get expensive brand-name tires, but you must get good quality. If you come across inexpensive tires of a brand you have not heard of, it's a good idea to avoid them. There's a chance they're decent tires, but it's best not to risk unknown territory.
Some tire dealers carry retread tires, also called recaps. These are used tires that have a new tread cap. They are less expensive than new tires, but they have a much higher blowout rate compared to new ones.
Note: A lot of studies say that recap tires are just as durable as new tires. Recap manufacturers maintain the vulcanizing process which bonds the new tread to the old tire is the same as with new tires, therefore just as good.
However, some of our drivers have not had good luck with retreaded tires. They've had problems with blowouts and tread separating from the tire, especially with heavy freight.
If you're buying tires for your truck, beware of unscrupulous dealers who would try to sell you recapped tires and pass them off as new. Look for these signs to see if the tires are recaps:
- The words “Bias” or “Bias Belted” on the sidewall
- The color of the tread is darker or lighter than the sidewall
- Seam or excess rubber on the sidewall
#2 Brakes
Your brakes are also subject to a lot of wear and tear. It takes a lot to stop a heavy truck that's moving at 70 mph (the length of two football fields, in fact!). You can reduce some of that wear with the right driving habits.
- Slow down by downshifting so that you don't have to rely on the brakes so much. It'll put less wear on brake parts, and smooth slowdowns and stops have been shown to improve fuel economy.
- When you're running in the mountains, braking for a long time on a downgrade heats the brake parts. If you generate a lot of heat from downhill braking, the cams expand and it can lead to brake failure!
- Use the engine brake, also known as the "Jake brake", while on a steep downgrade.
- Along with the engine brake, use "stab braking". When you start to go past the speed limit, use the service brakes to slow down about 10 mph. Release and allow the engine brake to do its thing until you get to the speed limit again.
Self Adjusting Brakes
Most tractors and trailers nowadays have self-adjusting brakes. But don't assume it's doing its job.
Inspect your brake adjustment every time you perform your pre-trip inspection.
Whenever you have your truck in the shop for any kind of maintenance, have the mechanic look at your brake parts. An experienced service tech knows how to tell if the brakes have defects before they cause problems.
Check the condition of brake pads and drums. Look for excess wear, cracks, and missing parts.
Listen for air escaping from the brake drums and air lines. If you hear leaks, call for roadside repair.
#3 Common Engine Breakdowns
The engine has a lot of moving parts: pistons, pushrods, crankshaft, and many others. They are moving throughout your whole workday, and that subjects them to a lot of wear and tear.
Even if you have a new truck that's still under warranty, your engine is subject to a breakdown.
Don't ignore engine noises. They are early signs that something's not right. Also, pay attention to unusual vibrations.
No doubt, you've had that thing happen where you take your truck to a mechanic and it doesn't make the noises. Don't worry about feeling silly he's seen it all before. Don't even worry about feeling foolish while trying to imitate the noises you heard.
Get to know the feel and sounds of your truck's engine. It can give you an early warning system.
#4 Electrical System Breakdowns
It seems like there are miles of electrical wire in a semi-truck. During your daily inspections, you want to be sure to look for frayed, burned, or broken wires. Look at the electrical wires under the hood, beneath the sleeper berth, underneath the trailer‚ anywhere you have wires.
Starter and Alternator
Your truck's alternator keeps the battery charged to run all electrical systems. When it goes out, you won't be able to keep the truck running much longer. If you don't use any electrical devices such as air conditioning or headlights, you might have about two hours of driving time once the alternator fails.
Check the battery gauge on the dashboard's instrument cluster. If it's not charging, have a mechanic check the alternator as soon as you can.
The starter is also subject to a lot of wear. Nowadays, a lot of city ordinances forbid idling your truck. You have to kill the engine almost every time you stop.
Sometimes the starter will crank slower than usual, which tells you that it's about to fail. Other times, when the bushings are well-worn, they can drain the battery.
Since the starter and alternator are completely tied to the electrical systems, it can be hard to tell if you have a problem with the battery, a failing alternator, or a bad starter. You'll need a mechanic's diagnosis.
#5 Fuel Systems
Leaks
Fuel leaks can happen when the fuel lines become brittle or are damaged from vibration and rubbing against other parts of the truck. Look for puddles of fluid beneath the tractor during your pre-trip inspections and whenever you stop during your workday.
Water and Fuel Contaminants
When you fuel your truck, there's a good chance that there's a small amount of water in the diesel. Although it's a trace amount, it can build up over several fuelings.
Water is a little heavier than diesel, so it tends to sink to the bottom of the tank. When a certain amount of water collects, the fuel pump draws it into the fuel lines.
Beneath the fuel filter, you'll find a short tube and a ball valve. The valve is also known as a petcock. This is the fuel system's water separator. Water in the fuel lines drops into this tube and you can drain it out by the ball valve.
But don't neglect to drain it regularly. If the water separator fills up, it'll contaminate the fuel lines.
If you see diesel fuel at or above the line on the fuel filter, be sure to change the fuel filter right away. If it gets too full, sediment gets released into the fuel lines and clogs the fuel flow.
Wrong Fuel Type
Commercial trucks are designed to run on petroleum diesel fuel. If you fill your tanks with gasoline or another incompatible fuel, the truck won't run.
Never put DEF into the fuel tanks. Only add it to the DEF tank.
#6 Cooling System
Low Coolant
During your pre-trip, make sure your coolant level is right. Check the level in the overflow reservoir. Never remove the radiator cap when the engine is hot. The coolant is under pressure and you run the risk of scalding.
Always fill the coolant from the overflow container.
Coolant Leaks
The coolant lines can break, causing coolant to drain out. If there's a sudden change in temperature, the hoses expand or contract. This can lead to line connectors or clamps leaking.
Check for pools of coolant beneath the cab and signs of leaks.
Water Pump
The pump that delivers the coolant is subject to a lot of wear since it's working whenever the engine is running. During your inspection, listen for unusual noises from the water pump. They could give an early warning that it's about to go out.
A Few Extra Pointers
Our top 3 pieces of advice on minimizing breakdowns include:
- Always buy good-quality tires and keep them properly inflated.
- Check your brake pads, drums, shoes, and other parts every day.
- Look for puddles of fluid beneath the cab during daily inspection and stops along your route.
Overall, it is highly recommended to keep records of suggested replacement times for parts according to their manufacturers' specs so you can keep this timeline top of mind.
Be diligent when you perform your inspections. If you see anything that looks questionable, be proactive and get an expert opinion as soon as possible.
Other relevant articles:
Understanding Diesel Engine Oil Viscosity and the Best Oil for Your Truck