2014 Isuzu NPR Serpentine Belt Routing & Length

As an ASE-certified master technician, I regularly see commercial workhorses like the 2014 Isuzu NPR in the shop for routine fleet maintenance. While Isuzu offers this truck with both the 5.2L 4HK1-TC diesel and the 6.0L GM-sourced V8 gas engine, the gas models utilize a traditional single serpentine belt system that is easy to service. Keeping up with this belt is crucial to preventing expensive downtime.

Below is your comprehensive reference guide for servicing the serpentine belt on a 2014 Isuzu NPR equipped with the 6.0L Gas V8 engine.

Quick answer: 2014 Isuzu NPR (6.0L Gas) Belt Specs

• Belt Length: 93.5 inches (approximate outside circumference)
• Rib Count: 6-rib
• OEM Belt Part Number: Isuzu 8-12626-222-0 (GM 12626222)
• Aftermarket Cross-References: Gates K060935, Dayco 5060935, Continental Elite 4060935
• Auto-Tensioner Part Number: Gates 38158 / ACDelco 38158
• Idler Pulley Part Number: Gates 38008 / ACDelco 38008

(Note: If your NPR has the 5.2L Diesel engine, the accessory drive uses a different multi-belt configuration. Always verify your engine code and VIN with your parts supplier before purchasing.)

Belt routing

Since we cannot render an image of the engine bay here, it is highly recommended that you take a clear photograph of your existing belt routing with your smartphone before you remove anything. This will save you a headache later if you get turned around.

For the 6.0L gas V8, the grooved side of the belt will ride on grooved pulleys, while the smooth back of the belt rides on the smooth idler and tensioner pulleys. The routing follows this path:

1. Start by looping the belt around the bottom of the Crankshaft pulley.
2. Route it up and over the Water Pump (smooth pulley).
3. Bring it down and around the Power Steering Pump.
4. Pull it straight up to the top corner over the Alternator.
5. Route it down under the smooth Idler Pulley.
6. Bring it across and over the A/C Compressor.
7. Finally, slip the belt under the Auto-Tensioner pulley (you will need to relieve the tension to slide it over this final pulley).

How to replace the serpentine belt

Replacing the belt on the 6.0L Isuzu NPR is a straightforward job thanks to the spring-loaded automatic tensioner.

1. Prepare your tools: You will need a dedicated serpentine belt tool or a long-handled 3/8" drive breaker bar.
2. Relieve tension: Locate the auto-tensioner on the passenger side of the engine block. Insert the 3/8" square drive of your tool directly into the square receptacle on the tensioner arm. Rotate the tensioner arm clockwise (toward the driver's side) to compress the spring and relieve tension on the belt.
3. Remove the old belt: Slip the belt off the tensioner or idler pulley, slowly release the tensioner arm, and then remove the belt from the remaining pulleys.
4. Inspect the pulleys: Spin all pulleys (idler, alternator, AC, power steering, water pump) by hand. They should spin smoothly with no grinding, squeaking, or wobble. If the tensioner is leaking grease or feels loose, replace it now.
5. Install the new belt: Route the new belt following the path described above, leaving the tensioner for last. Compress the tensioner again, slide the belt over the pulley, and carefully release the arm to apply tension. Ensure the belt ribs are perfectly seated in all pulley grooves before starting the engine.

Replacement interval

For commercial vehicles like the Isuzu NPR, preventative maintenance is the name of the game. The serpentine belt, tensioner, and idler pulley should typically be replaced every 60,000 to 90,000 miles. Because these trucks often idle for extended periods, engine hours can dictate replacement sooner than mileage. I recommend inspecting the belt at every oil change interval.

Signs of a failing belt or tensioner

Don't wait for a roadside breakdown. Keep an eye (and ear) out for these common warning signs:

• High-pitched squealing or chirping: Usually most noticeable on startup, this indicates a slipping belt, worn ribs, or a weak tensioner spring.
• Visual degradation: Look for fraying edges, chunks of missing rubber, deep cracking across the ribs, or a shiny, glazed appearance on the belt surface.
• Loss of accessories: A suddenly heavy steering wheel (loss of power steering), an overheating engine (water pump not turning), or a battery warning light (alternator not charging) mean the belt has likely snapped or slipped off completely.
• Tensioner bounce: If you look at the tensioner while the engine is running and see the arm bouncing violently, the internal damping mechanism has failed.

If you don't have the tools or time to tackle this repair yourself, let the professionals handle it to keep your fleet running smoothly. Find a trusted shop on Repairius.