Having a high-performing truck is a necessity in the transportation industry. One key aspect that is often overlooked but can significantly impact the health, power and fuel efficiency of any truck is the overhead adjustment. Let’s dive into what an overhead adjustment is, its benefits and how to know when it’s time for one.
What is an Overhead Adjustment?
An overhead adjustment, also known as a valve adjustment, is a routine service that involves adjusting the clearance between the valve train components in an engine. In simpler terms, it’s fine turning the heartbeat of a truck’s engine. By ensuring the proper clearance in the valve train, an overhead adjustment optimizes the engine’s performance and efficiency.
Benefits of an Overhead Adjustment
There are several benefits of an overhead adjustment, including:
- Improved Performance: Over time, a truck’s engine components can wear down, leading to decreased performance. An overhead adjustment restores the component tolerance, resulting in better performance and enhanced power.
- Enhanced Fuel Efficiency: A well-tuned engine is a more efficient engine. And with fine-tuned valve train components, an overhead adjustment can help improve fuel efficiency, saving you money in the long haul.
- Extended Engine Life: Regular overhead adjustments can prevent wear and tear on engine components. By maintaining proper valve clearance, you reduce the risk of valve damage and other costly repairs, helping extend the lifespan of your engine.
- Reduced Emissions: A tuned engine burns fuel more efficiently, resulting in fewer harmful emissions. If going green is your goal as a truck owner, overhead adjustments can help reduce your carbon footprint.
When it’s Time for An Overhead Adjustment
Wondering how to know when it’s time for an overhead adjustment? Here are some of the most common signs:
- Increased Engine Noise: If you notice your engine sounding louder than usual or unusual tapping or clicking noises, it could be time for an overhead adjustment.
- Decreased Performance: A decrease in power, acceleration or overall engine performance can indicate that the valves are not opening and closing as they should.
- Poor Fuel Efficiency: If you find yourself stopping for fuel more often, it may be time to have your engine checked and possibly an overhead adjustment.
- Scheduled Maintenance: Many manufacturers recommend overhead adjustments at specific mileage intervals. Here’s what our experts suggest based on engine model:
| CLASSIFICATION | ENGINE MODEL | INTERVAL |
| Heavy Duty | Cummins X15 CM2450 | 500,000 miles |
| Heavy Duty | Cummins ISX15 CM2350 | 500,000 miles |
| Heavy Duty | Cummins ISX15 CM2250 | 500,000 miles |
| Heavy Duty | PACCAR MX 13/11 EPA 2021 | LINE HAUL - 150,000 miles, then 300,000 miles SEVERE DUTY - 60,000 miles, then 300,000 miles |
| Heavy Duty | PACCAR MX 13/11 EPA 2017 | LINE HAUL - 150,000 miles, then 300,000 miles SEVERE DUTY - 60,000 miles, then 300,000 miles |
| Heavy Duty | PACCAR MX 13/11 EPA 2013 | LINE HAUL - 60,000 miles, then 300,000 miles SEVERE DUTY - 30,000 miles, then 300,000 miles |
| Heavy Duty | PACCAR MX 12 EPA 2010 | LINE HAUL - 60,000 miles, then 360,000 miles, then 300,000 miles thereafter SEVERE DUTY - 30,000 miles, then 330,000 miles, then 300,000 miles thereafter |
| CLASSIFICATION | ENGINE MODEL | INTERVAL |
| Medium Duty | Cummins L9 CM2450 | 150,000 miles |
| Medium Duty | Cummins ISL CM2350 |
150,000 miles |
| Medium Duty | Cummins B6.7 CM2450 | 150,000 miles |
| Medium Duty | Cummins ISB CM2350 | 150,000 miles |
| Medium Duty | PACCAR PX9 | 150,000 miles |
| Medium Duty | PACCAR PX7 | 150,000 miles |
An overhead adjustment is a simple yet important maintenance procedure that can bring new life into your truck. By optimizing engine performance, improving fuel efficiency and extending engine life, it’s a small investment worth making to keep your truck running for many miles to come.
Our experts are here to ensure your truck is running at peak performance. Click here to schedule a service appointment at your nearest MHC dealer today.