2025 GMC Yukon Serpentine Belt Routing, Length & Part Numbers

As an ASE-certified master technician, one of the most common maintenance items I see on modern SUVs is the accessory drive system. If you are servicing a 2025 GMC Yukon, getting the right serpentine belt and routing it correctly is crucial to keeping your alternator charging, water pump flowing, and climate control blowing cold.

The 2025 GMC Yukon is available with a few different engine options, most notably the 5.3L V8, the 6.2L V8, and the 3.0L Duramax inline-six turbo-diesel. The specifications below focus primarily on the popular V8 powertrains. Always verify your specific engine option when ordering parts, as belt lengths and part numbers can vary depending on the exact trim and engine configuration.

Quick answer

Here are the essential specifications and part numbers for the primary accessory drive belt on a standard 2025 GMC Yukon V8:

• Belt Length: 37.5 to 38.5 inches (varies slightly by aftermarket manufacturer for the main drive)
• Rib Count: 6-rib
• OEM Belt Part Number: ACDelco 12695666
• Aftermarket Cross-References: Gates K060373, Dayco 5060373, Continental Elite 4060373
• Auto-Tensioner Part Number: ACDelco 12668977 (Gates 39396)
• Idler Pulley Part Number: ACDelco 12668978

(Note: Many modern GM V8s utilize a separate, stretch-fit belt for the A/C compressor. The parts listed above are for the main serpentine drive).

Belt routing

Because modern engine bays are tightly packed, it is incredibly easy to forget the exact belt path once the old belt is off. Pro tip: Always take a clear photograph of your existing belt with your smartphone before you remove it. Since we cannot render an image here, follow this text-based step-by-step description of a traditional routing path:

1. Start by looping the belt around the bottom of the Crankshaft Pulley (the largest pulley at the bottom center of the engine).
2. Route the belt up and around the outside of the A/C Compressor.
3. Bring the belt across the smooth Idler Pulley (the smooth side of the belt will ride against this).
4. Pull the belt up and over the ribbed pulley of the Alternator at the top.
5. Route it down around the Power Steering pulley (if applicable to your specific hydraulic/electric setup).
6. Loop the belt under and around the Water Pump pulley in the center of the block.
7. Finally, slip the belt over the Auto-Tensioner pulley while applying pressure to the tensioner arm to create slack.

How to replace the serpentine belt

Replacing the belt on your Yukon is a straightforward job that can usually be completed in under 30 minutes.

Tools needed:

• A dedicated serpentine belt tool or a long 3/8" drive breaker bar.
• Safety glasses and gloves.

Step-by-step procedure:

1. Locate the automatic belt tensioner on the front of the engine block.
2. Insert your 3/8" breaker bar or serpentine belt tool into the square drive hole on the tensioner arm.
3. Rotate the tensioner arm (usually clockwise, but verify by the tensioner's spring direction) to relieve the tension on the belt.
4. While holding the tensioner open, slip the old belt off the easiest-to-reach smooth pulley (usually the idler or water pump).
5. Slowly release the tensioner arm and remove the old belt from the engine bay.
6. Route the new belt following the path described in the section above, leaving the tensioner or idler pulley for last.
7. Rotate the tensioner arm again, slip the new belt into place, and carefully release the tensioner.
8. Double-check that all ribs of the belt are seated properly in the grooves of every ribbed pulley.

Replacement interval

For the 2025 GMC Yukon, the recommended replacement interval for the serpentine belt is typically between 60,000 and 90,000 miles. However, as a master tech, I recommend inspecting the belt at every oil change once you surpass 50,000 miles. Modern EPDM belts do not crack the way older neoprene belts did; instead, the ribs wear down and lose material, much like a tire losing its tread.

Signs of a failing belt or tensioner

Don't wait for the belt to snap on the highway. Look out for these warning signs:

• Squealing or chirping noises: Especially on startup or when accelerating. This indicates the belt is slipping.
• Visible wear: Look for missing rib sections, fraying edges, or a shiny, glazed appearance on the back of the belt.
• Accessory failure: A heavy steering feel, dimming headlights, or an engine running hot can all point to a slipping belt.
• Tensioner bounce: While the engine is running, look at the tensioner arm. If it is bouncing excessively or making a rattling noise, the internal spring or dampener has failed, and the tensioner must be replaced alongside the belt.

If you don't feel comfortable tackling this repair yourself, don't sweat it. Find a trusted shop on Repairius.