Frequently Asked Questions About Peterbilt 375/377 Fan Blades & Shrouds

Will these fan blades and shrouds fit my specific year Peterbilt 375 or 377?

Most aftermarket fan blades and shrouds for Peterbilt 375/377 models are designed to fit trucks manufactured from 1987 through 2007. However, there are variations based on engine type (Cat, Cummins, or Detroit) and radiator configuration. Before ordering, check your current fan blade diameter and mounting bolt pattern. The most common sizes are 24", 26", and 28" diameter blades. If you're unsure, provide us with your VIN or call our tech support at 1-888-875-7787 for verification.

What's the difference between steel and composite fan blades, and which should I choose?

Steel fan blades are more durable and better suited for severe-duty applications or if you frequently haul heavy loads. They typically last longer but add more weight to your engine. Composite (fiberglass or nylon) blades are lighter, which reduces engine strain and can improve fuel economy by 1-2 mpg. They also run quieter but may need replacement more frequently in extreme conditions. For most over-the-road applications, composite blades offer the best balance of performance and efficiency.

Do I need to replace the fan clutch when installing a new fan blade?

While not always necessary, it's recommended to inspect your fan clutch whenever replacing the fan blade. Signs of a failing clutch include excessive fan noise when cold, overheating issues, or the fan not engaging properly. If your clutch is more than 300,000 miles old or showing these symptoms, replacing both components together can save labor costs and prevent future breakdowns. A worn clutch can also cause premature fan blade failure.

How difficult is the installation, and what tools will I need?

Installation typically takes 1-2 hours for someone with basic mechanical skills. You'll need a socket set (usually 15mm and 18mm), a torque wrench, and potentially a fan clutch wrench or holding tool. The main challenges are working in the tight space between the radiator and engine, and properly aligning the shroud. Always disconnect the battery first and ensure the engine is cool. Torque specifications vary by model but typically range from 45-55 ft-lbs for blade bolts.

Why is proper shroud fitment so important, and how much clearance should I have?

The shroud directs airflow through the radiator for optimal cooling efficiency. Improper fitment can cause overheating, reduced fuel economy, and fan blade damage. Your fan blade tips should have 0.75" to 1.5" clearance from the shroud on all sides. Too much gap reduces cooling efficiency, while too little risks blade contact during engine movement. The shroud should also overlap the radiator core by at least 1" on all sides to prevent air bypass.