What Is The Most Reliable Semi Truck Engine?

Iron Buffalo icon
Iron Buffalo Truck & Trailer
September 15, 2023
What Is The Most Reliable Semi Truck Engine?

When you are trying to purchase a new semi-truck, you will need to pay special attention to its engine. In other words, you will need to proceed with buying the most reliable semi-truck engine. Then you can continue to drive the semi-truck without experiencing any hassle. Here are some of the most reliable semi-truck engines that you can find out there. 

Volvo D11

The smallest diesel engine Volvo provides is the D11. It trades off brute power for increased fuel efficiency. Volvo takes great pleasure in the D11's modest weight, highlighting in its brochure how the most recent version of the D11 engine weighs 17 pounds less than the previous one. The nine kinds of this engine. At the ideal RPM of about 1000, they produce 325-425 horsepower and 1250–1550 pound–feet of torque. Two of the nine are categorized as "Eco-Torque" and two as "XE."

Depending on the amount of power required, Eco-Torque engines may switch between two different driving modes. The engine will switch to High Torque mode if it detects that doing so is necessary to pull greater loads or climb hills. However, it will mostly remain in Low Torque mode to maximize fuel economy, lower pollutants, and save money on diesel. The only torque mode offered by XE engines prevents the driver, except in extremely limited circumstances, from using the highest gear. This function, like Eco-Torque, aids the driver in fuel efficiency.

Volvo offers several warranties depending on the vehicles and components. On their website, they adamantly advise that you speak with the local Volvo truck dealer for further details.

Paccar PX7 

The PX-7 truck engine is the most basic of the four PACCAR truck engines, but it more than makes up for its lack of raw power with durability and reliability. The performance metrics come first. The PX-7 is a little vehicle that comes in eleven varieties with peak torque ratings ranging from 520 to 800 pound-feet and horsepower ratings from 200 to 360. The PX-7's strongest variety is less potent than the MX-13's weakest variation, and PACCAR themselves advise using the PX-7 exclusively with medium-duty cars.

This is not meant to imply that the PX-7 has no value. This engine is far lighter than most, with a dry weight of under 1,200 pounds, which reduces fuel usage. PACCAR takes great pride in the PX-7's durability and backs it up with a 3-year, unlimited-mile guarantee. To surpass infinity is difficult. In addition, PACCAR provides extended warranties that cover the engine for long periods of time.

The PX-7's ease of maintenance is another appealing feature. The driver and fleet owner simply need to keep in mind 15-15-200: Whereas other engines have a lengthy list of maintenance intervals for different sections depending on what proportion of utilization is idling 20,000 miles for the diesel exhaust fluid (DEF) filter, 15,000 miles for the oil and filter, and 20,000 miles for the fuel filter.

Although a PX-7 may not perform as expected in a class 8 vehicle, any smaller trucks in your fleet will benefit from its excellent fuel efficiency, extended lifespan, and ease of use.

Paccar PX9 

The PX-9, the PX-7's stronger sibling, is marketed primarily for its power-to-weight ratio. Its eleven variations vary in horsepower from 260 to 450, with peak torque at equivalent revolutions per minute ranging from 720 to 1250 pound-feet (RPM).

The higher-end variants are suitable for heavy-duty trucks, but even if your fleet is medium-duty, the lower-end PX-9s offer features like removable wet liners on their cylinders and bypass oil filtering that are often only found in heavy-duty vehicles.

The PX-9's maintenance schedule is relatively similar to the PX-7's, however, if the engine is fitted with a coolant filter, the formula changes to 15-15-15-200. The PX-9's warranty is substantially more constrained than the PX-7's at two years and 250,000 miles. However, plan extensions are available.

The PX-9 is a really mid-range engine. The PX-9 versions are a wonderful match for your vehicle, whether you want a medium-duty truck to have the added "oomph" of a heavy-duty truck or a large hauler to have some of the simplicity of a medium-duty engine.

Detroit DD5

Three different models of the Detroit DD5 are available, each with 200–240 horsepower and 560-660 lb.–ft of torque. It is intended for medium-duty trucks like the Freightliner M2 106 and has a 400,000-mile B10 life. According to testing, 90% of all DD5 engines lasted 400,000 miles before necessitating an engine rebuild in its entirety.

A sophisticated mechanism that optimizes the quantity of fuel injected each time is another feature of the engine's fuel efficiency design. When used properly, the engine can get over 12.0 miles per gallon (MPG) of diesel fuel, according to Detroit Diesel.

Detroit claims that the DD5 is the best in class when it comes to maintenance planning. The engine oil and filter only need to be replaced every 50,000 miles for basic long-distance driving, and the same rule also applies to the fuel filter. Every 100,000 miles, the valve lash must be adjusted, every 225,000 miles, the diesel particulate filter must be changed, and every 500,000 miles, the DEF pump filter must be changed.

The DEF pump filter will outlive the engine warranty since Detroit backs the DD5 with a three-year, 250,000-mile guarantee.

Detroit DD8

The Detroit DD8 and the Detroit DD5 have many similarities. Both feature a sophisticated fuel injection system, a 400,000-mile B10 life, and a three-year, 250,000-mile standard warranty.

Performance, fuel economy, and maintenance are the areas where they diverge. There are seven different models of the DD8, each with 260–375 horsepower and 660–1050 lb–ft of torque (although the highest end, 375 horsepower and 1050 ft-lb torque, is reserved for emergency and recreational vehicles only). When driven properly, the DD8 achieves 8.5 MPG.

Compared to its smaller sibling, the DD8 has longer maintenance intervals: 60,000 miles for the engine oil, fuel filter, and fuel filter; 120,000 miles for valve lash adjustment; 150,000 miles for cleaning the diesel particulate filter; and 500,000 miles for the DEF pump filter.

For trucks that serve certain functions, such as bucket trucks, dump trucks, tow trucks, and similar commercial vehicles, Detroit employs the DD8.

Final words

When you buy a semi-truck with one of these engines, you don’t need to worry too much about performance or functionality. Just go for it, and you will never be disappointed with your investment as well.