Serpentine Belt Replacement on the HEMI: DIY Guide

When to Replace the Serpentine Belt

Replace the serpentine belt:

• Every 60,000–100,000 miles (check your owner's manual)
• If you see cracking, fraying, glazing, or rib wear
• If you hear squealing at startup or under load

Tools Required

• 3/8" drive breaker bar or serpentine belt tool
• Replacement belt (Gates, Continental, or Dayco — avoid no-name brands)
• Belt routing diagram (on sticker under hood or in your owner's manual)

Belt Routing

The 5.7L and 6.4L HEMI belt routes differ slightly based on whether you have A/C, a supercharger idler, etc. Before removing the old belt, photograph the routing or locate the underhood sticker. Re-routing incorrectly causes immediate failure or accessory damage.

Step-by-Step Removal

1. Locate the tensioner pulley — spring-loaded, typically on the driver's side of the engine
2. Insert breaker bar into tensioner square drive
3. Rotate tensioner clockwise (on most HEMI configurations) to release tension
4. Slide belt off the alternator pulley (easiest slip point) while holding tension
5. Slowly release tensioner
6. Remove old belt

Installation

1. Route new belt following the diagram — every pulley except the tensioner
2. Using breaker bar, rotate tensioner clockwise
3. Slip belt over alternator pulley while holding tension
4. Slowly release tensioner onto belt
5. Verify belt sits centered in all pulley grooves — no edges hanging off

Run the Engine and Verify

Start the engine. Watch the belt for 30 seconds at idle. It should run smoothly with no wobble. Listen for squealing (misrouted belt or pulley issue).

Idler Pulley and Tensioner

If the old belt shows uneven wear or the new belt squeals after installation, suspect the tensioner or an idler pulley. These can be replaced individually. Tensioner failure is common after 80,000–100,000 miles — replace it proactively when doing a belt service.

Cost: OEM belt ~$30. Tensioner ~$40. Total DIY cost under $100 vs $200–300 at a shop.