At All American Truck Sales, we've inspected thousands of used semi trucks during our 35+ years in the industry. While we meticulously evaluate every truck in our inventory, we believe informed buyers make better decisions. Here are the 8 most critical points to inspect when evaluating any used semi truck.

1. Engine Performance

Start the engine and listen carefully for:

• Unusual knocks or rattling noises

• Excessive smoke from the exhaust

• Uneven idle or hesitation

• Proper oil pressure readings

A well-maintained engine should start promptly and run smoothly without concerning noises or visible smoke.

2. Service History Documentation

Complete maintenance records are gold when evaluating a used truck. Look for:

• Regular oil and filter changes

• Scheduled maintenance at appropriate intervals

• Any major repairs or component replacements

• Consistent service dating back as far as possible

Gaps in maintenance history often suggest neglect and can predict future problems.

3. Transmission and Drivetrain

Test all gears under various conditions when possible:

• Listen for grinding or whining noises

• Check for smooth, consistent shifting

• Test for clutch slippage in manual transmissions

• Verify no delay or hard shifts in automated transmissions

Transmission repairs are costly, making this inspection point especially important.

4. Frame and Structural Integrity

Examine the frame rails and structural components for:

• Cracks, bends, or signs of welding repairs

• Rust or corrosion, especially in cross members

• Proper alignment with no signs of twisting

• Secure fifth wheel mounting with no excessive wear

Frame issues can be dangerous and are often expensive or impossible to properly repair.

5. Brake System Condition

A thorough brake inspection should include:

• Even wear on brake pads and drums

• No signs of leaking hydraulic components

• Proper air pressure build-up and hold

• Functional ABS system with no warning lights

Never compromise on brake system integrity – it's critical for safety and compliance.

6. Tire and Suspension Condition

Examine all tires and suspension components:

• Even tire wear across all positions

• Matching tire brands and tread depths

• No cracks or bulges in air suspension components

• Shock absorbers free from leaks or damage

Uneven tire wear often signals underlying suspension problems that should be addressed.

Fun Fact– All our trucks sold here are All American Truck Sales come with new drive tires! 

8. Electrical Systems and Electronics

Test all electrical components thoroughly:

• All lights and signals working properly

• Gauges displaying accurate readings

• Battery condition and charging system output

Electrical issues can be frustratingly intermittent and time-consuming to diagnose and repair.

Let Our Experts Help You

At All American Truck Sales servicing the Chicago area, every truck in our inventory undergoes this comprehensive inspection and more before being offered for sale. Our experienced team can guide you through this inspection process on any of our available models.

Call us at 563-587-8844 or visit our dealership at 175 N Crescent Ridge, Dubuque, Iowa to experience the difference professional inspection makes in your truck buying journey.

Need help inspecting a used semi truck? Trust the experts at All American Truck Sales. With over three decades of experience inspecting commercial trucks, we know exactly what to look for to ensure you make a sound investment.