Onsite Truck & Equipment Repair Blog

Kenworth T800: Troubleshooting Common Issues and Solutions


There's not much we can say about the Kenworth T800 that hasn’t been said before. If you’ve had the pleasure to get behind the wheel of one or have them in your fleet, you already know what absolute beasts they are. You’ll also know that, despite their robust nature, they can still fall prey to a range of issues. 

Whether you’re a seasoned trucking veteran or you’re new to the Kneworth club and want to stay ahead of repairs, this guide has something for you. Here, you’ll learn about the issues that can plague your Kenworth and, most importantly, what you can do to solve them! 

Section 1: Common Issues Overview

Engine Problems

Kenworth T800s can be equipped with PACCAR MX, Caterpillar C13, Detroit engines, and  Cummins engines. Regardless of which one powers your truck, they all can encounter issues like overheating, power loss, or strange noises. These problems can often be traced back to coolant leaks, clogged filters, or complications with the fuel system.

Deeper inspections can reveal issues like turbocharger failures or exhaust system blockages, leading to decreased efficiency and increased fuel consumption. Staying vigilant about your engine’s temperature and exhaust quality is a great way to preempt any critical failures.

Transmission Issues

Troubles with the transmission that manifest through hard shifts or peculiar noises often originate from low fluid levels or clutch wear. However, deeper issues might involve the transmission's electronic controls or sensor failures, leading to more complex diagnostic requirements. Regularly checking the transmission fluid's quality—not just its level—can provide early warnings of these issues.

Electrical System Failures

Modern trucks’ electrical systems are complex pieces of equipment that require specialist attention due to their diverse nature. Components can range from electronic control units (ECUs) that require regular software updates to batteries and alternators that need routine inspections and cleaning. Issues like erratic sensor readings or unexpected warning lights often signal the need for a comprehensive electrical system check.

Braking System Concerns

While worn shoes or leaks in the compressed air system are common, the intricacies of modern braking systems, including the ABS, call for specialized knowledge for effective troubleshooting. Regular checks should extend beyond physical components to include diagnostic scans for electronic components as well as real-world testing to ensure the effectiveness of the repairs.

Suspension and Steering Problems

Uneven tire wear or handling issues hint at suspension troubles, but the root causes can be varied, from worn shock absorbers to damaged suspension bushings. Steering issues, particularly in vehicles like the T800, can also stem from hydraulic system faults or misaligned wheels, emphasizing the need for comprehensive vehicle inspections.

Section 2: Troubleshooting and Solutions 

Step-by-Step Troubleshooting

Beginning with visual inspections and simple diagnostic tests can often resolve straightforward issues. For more complex problems, using diagnostic software to read ECU fault codes becomes invaluable. This approach can quickly pinpoint problems that are not immediately apparent from a physical inspection.

DIY Solution

Equipping yourself with basic tools and a diagnostic scanner can empower you to address a range of common problems. For example, changing filters and fluids and even performing minor sensor replacements can often be done without professional help, provided safety guidelines are strictly followed.

Remember to always prioritize your safety when doing this. Make sure the truck is secure and turned off, and you’re wearing the correct PPE, like glasses, boots, and insulating gloves.

When to Seek Professional Help

Recognizing the limits of DIY repairs is crucial. Complex transmission repairs, in-depth electrical troubleshooting, and major engine overhauls should be entrusted to professionals. These experts have the tools, training, and experience to handle sophisticated systems, ensuring repairs are done correctly and safely.

Section 3: Preventive Maintenance Tips

Regular Inspection and Maintenance Schedule

Prevention is better than cure, and that comes with a strict maintenance schedule. Utilizing fleet maintenance software can help streamline these processes and automate aspects of them, including service intervals. This way, you can save time on tedious aspects of maintenance and focus your efforts elsewhere.

Specific Maintenance Tips for the Kenworth T800

Using the latest lubricants and filtration technology can extend the life of critical components. Synthetic oils and advanced fuel filters, for instance, can provide superior protection and efficiency compared to conventional options.

The Role of Driver Behavior

Encouraging drivers to adopt a proactive stance towards maintenance—such as conducting pre-trip inspections and reporting any anomalies immediately—can greatly enhance the operational lifespan of the vehicle. Educating drivers on the impact of their driving style on vehicle wear and tear is also beneficial.

Section 4: Upgrades and Modifications 

Recommended Upgrades for Longevity and Performance

Investigating beyond conventional upgrades and exploring advanced telemetry systems can offer larger insights into vehicle performance and maintenance needs. These systems can track everything from fuel efficiency to component wear, enabling predictive maintenance strategies that preempt failures.

Cost-Benefit Analysis of Common Upgrades

When considering upgrades, evaluating their impact on the total cost of ownership is essential. For instance, while aftermarket parts might seem like cheaper alternatives, the extra maintenance and repairs that come with them will quickly counteract the initial lower investment.


Regular maintenance, proactive troubleshooting, and strategic upgrades are essential for ensuring the reliability and longevity of your Kenworth T800. By staying informed about common issues and following preventive maintenance practices, you can minimize downtime and maximize efficiency. Remember, when in doubt, consult with experts to address complex issues and keep your T800 running smoothly for years to come! 

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