The serpentine belt on a 5.7 Hemi drives the alternator, power steering, and air conditioning (and, on some setups, the water pump). You’ll know it’s failing from noises, visible wear, looseness, and performance problems. If you notice any of these signs, inspect and plan for replacement promptly.
Common warning signs
These are the most frequent indicators that the belt needs attention. Look for multiple signs to confirm wear or failure.
- Squealing, chirping, or whining noises from the engine bay, especially on startup or when revving
- Visible cracking, fraying, glazing, or chunks missing from the belt
- A glossy, glazed belt surface or hard, brittle feel when you run your fingers along it
- Cracked or missing ribs, edge wear, or belt misalignment with pulleys
- Excessive belt slack or a belt that rides high/low on pulleys
- Electrical or cooling symptoms such as a dim battery light, weak or failing power steering, or AC that won’t engage
- Overheating or reduced heater performance if the belt drives the water pump (in engines that do)
If you notice any of these signs, get the belt and belt-driven pulleys inspected promptly and plan for replacement as needed.
How to inspect and diagnose
Follow these steps to assess belt condition and tension safely and accurately.
- Park on a flat surface, engine off, and the keys out. Let the engine cool before you touch anything.
- Open the hood and locate the serpentine belt routing and the tensioner pulley. If you have a service diagram, use it to verify routing.
- Visually inspect the entire belt for cracks, fraying, glazing, missing ribs, or signs of wear along the length and at the belt edges.
- Check belt tension by hand with the engine off: the belt should have minimal side-to-side play and should not feel overly loose. Do not force the belt; if in doubt, do not pry on it.
- Check the tensioner and idler pulleys for smooth operation: rotate by hand (engine off) and listen for roughness or grinding; check for wobble or misalignment in pulleys.
- If you hear squeal when starting the engine or while running, or you observe any belt wear, plan to replace the belt and, if necessary, the tensioner and idler.
Regular inspection helps catch wear before it breaks, reducing the risk of belt-driven accessory failure while driving.
Replacement considerations and maintenance
If the belt is worn or damaged, replacing it is prudent. Consider replacing the belt along with the tensioner/idle pulleys to restore reliable operation.
- Ensure you have the correct belt size and, if applicable, the correct tensioner/idle pulleys for your 5.7 Hemi; check your owner’s manual or parts diagram for the exact part number.
- Relieve belt tension with the tensioner tool or a wrench, loosen, and carefully slide the belt off the pulleys. Take a photo or note routing for reinstallation.
- Install the new belt, following the routing diagram precisely. Ensure the belt seats fully into the pulley grooves on all accessories.
- Recheck tension and alignment after installation; start the engine and observe that all accessories run smoothly without slipping or noise.
- Consider replacing the tensioner and idlers if they show any wear or noise; a failing tensioner can accelerate belt wear.
Note: belt life varies with driving conditions and maintenance. Typical OEM-recommended replacement intervals range from about 60,000 to 100,000 miles, but inspect more frequently in harsh conditions or if your vehicle has high mileage or has experienced previous belt failures.
When to seek professional help
If you are unsure about diagnosing belt wear, or if you’re uncomfortable removing or installing a serpentine belt, have a qualified technician inspect or replace the belt and tensioner to avoid injury or engine damage.
Summary
Key signs of a worn serpentine belt on a 5.7 Hemi include noises such as squealing, visible wear like cracks or fraying, glazing or cracking, and performance symptoms like dim lights or poor AC. Visual inspection, tension checks, and pulley condition are essential. If the belt shows wear or the tensioner is weak, replace the belt (and often the tensioner/pulleys) to prevent a breakdown. Regular checks at routine service intervals help keep the belt in good condition and avoid surprise failures.