2020 Isuzu NPR Serpentine Belt Routing, Length & Part Numbers

As an ASE-certified master technician, I’ve serviced countless commercial work trucks, and the 2020 Isuzu NPR is a staple in many fleets. Keeping these trucks on the road means staying on top of routine maintenance, and the serpentine belt drive system is a critical component that should never be ignored.

For this guide, we are focusing on the highly common 6.0L GM V8 Gas engine option found in the 2020 Isuzu NPR. If your truck is equipped with the 5.2L 4HK1-TC diesel engine, please note that belt lengths, routing, and part numbers will differ.

Quick answer

Here are the crucial specifications and part numbers you need for the 2020 Isuzu NPR (6.0L Gas V8) serpentine belt drive system:

• Belt Length: 93.0 inches (Outside Circumference)
• Rib Count: 6-rib
• OEM Belt Part Number: GM 12626222 / Isuzu 8983248380
• Aftermarket Cross-References: Gates K060930, Dayco 5060930, Continental Elite 4060930
• Auto-Tensioner Part Number: Gates 38159 (or ACDelco 38159)
• Idler Pulley Part Number: Gates 38008

Belt routing

Since we cannot render an image here, it is extremely important to take a clear photograph of your existing belt routing before you remove it. This ensures you have a personal reference tailored to your specific truck's accessory layout.

For the 6.0L V8 2020 Isuzu NPR, the standard serpentine belt routing path flows as follows:

1. Start by looping the belt around the bottom of the main Crankshaft Pulley.
2. Route the belt down and around the A/C Compressor.
3. Bring the belt up and under the smooth Idler Pulley.
4. Pull the belt up and over the top of the Alternator.
5. Route it across to the Power Steering Pump.
6. Bring it down and under the smooth pulley of the Water Pump.
7. Finally, pull the loop back towards the Auto-Tensioner to provide the slack needed to slip the belt over the final pulley.

Always ensure the ribbed side of the belt rides on the ribbed pulleys (crank, A/C, alternator, power steering) and the smooth side of the belt rides on the smooth pulleys (idler, water pump, tensioner).

How to replace the serpentine belt

Replacing the serpentine belt on a 2020 Isuzu NPR is a straightforward job that can usually be completed in under 20 minutes with the right tools.

Tools required:

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

Step-by-step instructions:

1. Locate the tensioner: Find the automatic belt tensioner on the front of the engine block. It will have a 3/8" square drive hole cast directly into the tensioner arm.
2. Release the tension: Insert your 3/8" breaker bar or serpentine belt tool into the square drive hole. Rotate the tensioner arm to relieve tension on the belt.
3. Remove the old belt: While holding the tensioner back, slip the old belt off the easiest accessible pulley (usually the idler or alternator). Carefully release the tensioner and unthread the old belt from the engine bay.
4. Route the new belt: Following your reference photo and the routing path outlined above, thread the new belt around all pulleys except for the final one.
5. Install the new belt: Rotate the tensioner once more to create slack, slip the belt over the final pulley, and slowly release the tensioner.
6. Verify seating: Double-check every single pulley to ensure the belt ribs are perfectly seated in the pulley grooves before starting the engine.

Replacement interval

For commercial vehicles like the Isuzu NPR, preventative maintenance is the key to preventing downtime. The serpentine belt and the automatic tensioner should be inspected every 30,000 miles. As a rule of thumb, you should plan to replace the serpentine belt every 60,000 to 90,000 miles.

I highly recommend replacing the auto-tensioner and idler pulley at the same time as the belt. Tensioners lose spring rate over time, and idler pulley bearings dry out. Replacing them as a set ensures total system reliability.

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 cold startups or when the A/C compressor engages. This indicates belt slip or a weak tensioner.
• Visible wear: Look for missing ribs, deep cracking, fraying edges, or a shiny, glazed appearance on the belt's ribbed side.
• Tensioner bounce: While the engine is idling, watch the tensioner arm. A slight vibration is normal, but excessive bouncing or jumping indicates the internal dampener has failed.
• Heavy steering or overheating: If the belt slips badly, it can under-drive the power steering pump or water pump.

If you don't have the time or tools to tackle this job yourself, don't risk your fleet's uptime. Find a trusted shop on Repairius.