Frequently Asked Questions About Peterbilt 359 Fan Blades & Shrouds
Will these fan blades and shrouds fit my specific year Peterbilt 359?
Most fan blades and shrouds for the Peterbilt 359 are compatible with models from 1967-1987, as the cooling system remained relatively consistent throughout production. However, there are variations between early models (1967-1972) and later models (1973-1987) in mounting hole patterns and shroud dimensions. Always verify your engine model (CAT, Cummins, or Detroit) as this affects fan blade pitch and diameter requirements. We recommend checking your existing fan blade part number or contacting us with your OEM for exact fitment confirmation.
What's the difference between steel and aluminum fan blades, and which should I choose?
Steel fan blades are heavier but more durable, typically lasting longer in severe-duty applications and providing better cooling at lower RPMs. Aluminum blades are lighter, reducing strain on your water pump and bearings while improving fuel economy slightly. For daily drivers and highway trucks, aluminum works well. For heavy-haul, vocational, or extreme temperature conditions, steel is preferred. Both materials are available in standard and high-performance configurations with varying blade counts (typically 7-11 blades).
Do I need to replace my fan clutch when installing a new fan blade?
While not always necessary, it's highly recommended to inspect your fan clutch whenever replacing the fan blade. A worn clutch can cause premature blade failure, excessive noise, and poor cooling performance. Signs you need a new clutch include: oil leakage around the clutch body, fan freewheeling when engine is hot, or excessive play when wiggling the fan blade. If your clutch is over 5 years old or has 200,000+ miles, consider replacement as preventive maintenance.
Can I upgrade to a larger diameter fan and shroud for better cooling?
Upgrading fan diameter is possible but requires careful consideration. Moving from a standard 24" to a 26" or 28" fan requires a matching shroud and adequate clearance from radiator, hoses, and frame rails. Larger fans move more air but also create more parasitic drag on the engine. Ensure your fan clutch is rated for the larger blade weight and that your alternator and A/C compressor brackets won't interfere. Many drivers find that a properly matched OEM-size setup with a quality fan clutch provides optimal cooling without modifications.
Why is my new fan blade making noise, and how do I ensure proper installation?
Fan noise usually indicates improper installation or component mismatch. Common causes include: incorrect spacer thickness between fan and clutch, bent or imbalanced blades, misaligned shroud causing blade contact, or wrong fan pitch for your application. During installation, ensure the fan blade has 1-1.5 inches clearance from the shroud on all sides, use a dial indicator to check blade runout (should be less than 1/8"), and torque mounting bolts to manufacturer specifications (typically 35-45 ft-lbs). Always install blades with the concave side facing the radiator and verify the rotation arrow matches your engine rotation.
