2017 Peterbilt 389 Serpentine Belt Routing & Replacement Guide

Quick Answer

• Belt Length: Varies by engine configuration (see below for specific engine details)
• Rib Count: 8-rib (common for heavy-duty applications)
• OEM Belt PN: Varies by engine
  • For Cummins ISX15: Expected PN 4962967 (verify with VIN)
  • For PACCAR MX-13: Expected PN 1933069PE (verify with VIN)
• Aftermarket Cross-references:
  • Gates: K08xxxxRP (Verify specific engine application)
  • Dayco: 508xxxx (Verify specific engine application)
  • Continental Elite: 408xxxx (Verify specific engine application)
• Auto-Tensioner PN: Varies by engine
  • For Cummins ISX15: Expected PN 4930600 (verify with VIN)
  • For PACCAR MX-13: Expected PN 1930263PE (verify with VIN)
• Idler Pulley PN: Varies by engine
  • For Cummins ISX15: Expected PN 3698889 (verify with VIN)
  • For PACCAR MX-13: Expected PN 1930264PE (verify with VIN)

Belt Routing

The 2017 Peterbilt 389 can be equipped with either the Cummins ISX15 or the PACCAR MX-13 engine, and the serpentine belt routing will vary slightly between these two. Before you begin any work, it is crucial to take a clear photograph of your current belt's routing path from multiple angles. This will serve as an invaluable reference during reinstallation.

Here’s a general text-based description of a common heavy-duty serpentine belt routing, which you can adapt to your specific engine by observing your photo:

1. Begin at the crankshaft pulley (the lowest, largest pulley).
2. From the crankshaft, the belt typically travels up to the A/C compressor pulley.
3. From the A/C compressor, the belt may run to an idler pulley for proper tension and alignment.
4. Next, the belt wraps around the alternator pulley.
5. From the alternator, it often proceeds to the power steering pump pulley.
6. Following the power steering pump, it will engage the water pump pulley.
7. Finally, the belt routes to the automatic tensioner pulley, which maintains proper belt tension across all accessories.

Remember to verify this against your engine's specific configuration using the photos you took. If your truck has additional accessories, the path may include more idler pulleys or accessory drive pulleys.

How to Replace the Serpentine Belt

Replacing the serpentine belt on a 2017 Peterbilt 389, while not overly complicated for an experienced technician, requires proper tools and attention to detail.

Tools You'll Need:

• Serpentine belt tool or a long 3/8" drive breaker bar
• Socket to fit the tensioner arm (usually 1/2" or 3/4")
• New serpentine belt
• Possibly a pry bar (for stubborn tensioners)

Steps:

1. Safety First: Ensure the engine is off and cool. Disconnect the negative battery cable to prevent accidental starts.
2. Document and Remove: Refer to the photographs you took of the belt routing. Locate the automatic belt tensioner. Insert your serpentine belt tool or breaker bar into the square drive opening on the tensioner arm. Apply pressure to release the tension on the belt. While holding the tensioner, carefully slip the old belt off one of the easier pulleys (like the alternator or power steering pump).
3. Inspect Pulleys: With the old belt removed, take this opportunity to manually spin each pulley (alternator, power steering, A/C compressor, idlers, water pump). Listen for any grinding, squeaking, or excessive play. Worn pulleys should be replaced to prevent premature belt failure.
4. Install New Belt: Route the new serpentine belt according to your photographs and the diagram on your engine (often found under the hood). This is where your photos are crucial. Ensure the ribbed side of the belt is properly seated in the ribbed pulleys and the smooth side is against any smooth idler pulleys.
5. Tension and Verify: Once the belt is almost fully routed, use your serpentine belt tool or breaker bar to again release the tensioner. Slip the remaining part of the belt onto its final pulley. Slowly release the tensioner, allowing it to apply pressure to the new belt. Double-check all pulleys to ensure the belt is properly seated on each one. Start the engine briefly and check for any belt squeal or misalignment. If everything looks good, reconnect the battery.

Replacement Interval

The serpentine belt on a heavy-duty truck like the Peterbilt 389 is a critical component. While there isn