Accessory Drive Belt Guide for the 1981-1985 Mack RWS
Your classic Mack RWS uses multiple V-belts, not a single serpentine belt; here’s what you need to know to choose the right replacement.
- Your 1981-1985 Mack RWS uses multiple V-belts, not a single serpentine belt; you must confirm the layout before ordering.
- If you experience repeated belt failures, the cause is likely a misaligned pulley or failing accessory, not the belt itself.
- Stick with reputable heavy-duty aftermarket brands like Gates, Continental, or Dayco for reliable performance.
- Before installing a new belt, always inspect the pulleys for wear and clean the grooves to ensure better grip and longevity.
Signs of a Failing Accessory Drive Belt
A failing V-belt on your Mack RWS gives several warning signs. Ignoring them can lead to a breakdown and costly engine damage. Be alert for these symptoms:
- Squealing Noises: A high-pitched squeal, especially when starting the engine or under heavy load, is a classic sign of a slipping, worn, or loose belt.
- Visible Wear and Damage: Inspect your belts regularly. Look for cracks, fraying, missing chunks, or a glazed, shiny appearance on the belt's surface. Any visible damage means the belt needs immediate replacement.
- Accessory Malfunctions: If your battery isn't charging (dimming headlights, battery warning light), your engine temperature is rising, or you lose power steering assist, a failed belt is a likely cause.
- Vibrations or Ticking Sounds: A belt that is shredding or has a piece missing can cause a rhythmic ticking or slapping sound as it hits other components in the engine bay.
A Note on Repeated Belt Failures
If your truck shreds or throws belts frequently, the belt itself is probably not the root cause. This issue often points to a bigger problem, such as misaligned pulleys, a bent bracket, or a failing accessory with a bad bearing (like a seized alternator or water pump). Always investigate the pulleys and accessories when replacing a shredded belt.
Choosing the Right Aftermarket Drive Belt
For a classic workhorse like the Mack RWS, high-quality aftermarket V-belts are the industry standard for replacement. Brands like Gates, Continental, and Dayco all manufacture reliable heavy-duty belts.
- Gates: Often considered a top-tier choice by professional mechanics, especially their heavy-duty lines like the FleetRunner. They are known for durability and solid construction.
- Continental: Also a highly-regarded brand, Continental (sometimes sold as ContiTech) is a major OEM supplier and produces belts known for quiet operation and longevity.
- Dayco: A well-established brand that offers quality belts, often praised for their material composition and flexibility.
For most applications on the RWS, any of these three brands will provide dependable service. The most important factor is ensuring you order the correct belt length and profile for the specific accessory you are servicing.
Estimated Replacement Costs
| Part Type | Estimated Cost (Per Belt) |
|---|---|
| New Aftermarket V-Belt | $14.43 - $47.56 |
| Shop Labor | $150 - $300 |
Cost estimates are for a single belt replacement and can vary based on region and the specific belt being replaced. Labor costs may be higher if multiple belts are replaced at once.
Frequently Asked Questions (FAQ)
Does my 1981-1985 Mack RWS have a serpentine belt?
No. Your truck uses a multiple V-belt system, not a single serpentine belt. The exact number of belts depends on the engine and accessories like A/C. You will have separate belts for different components. It's best to inspect your engine to confirm the number and size of belts you need before ordering.
Why does my truck keep breaking or shredding belts?
If you are replacing belts frequently, there is likely an underlying issue. The most common causes are a misaligned pulley, a worn-out pulley groove, or a failing accessory (like a water pump or alternator) with a bad bearing that causes drag or wobble. Have a mechanic inspect the entire drive system.
Is there a quality difference between Gates, Continental, and Dayco?
All three are reputable manufacturers of high-quality belts. Many professional mechanics have a personal preference, but for most uses on a heavy-duty truck, any of these brands will provide reliable service. Gates is often specifically mentioned for truck applications.
Can I replace the V-belts myself?
If you have mechanical experience, replacing the V-belts on an RWS is a manageable job. Access is generally better than on modern, compact engine bays. You will need basic hand tools and likely a long pry bar to create tension when installing the new belts. However, if you are not comfortable with this type of work, it is best to leave it to a professional.
Technical Specifications
OEM Part Numbers: 88GB439P406
System Type: Multiple V-Belts. Belt material is typically EPDM rubber. The exact length, width, and V-angle of the belt are critical and vary based on the truck's specific engine and accessory configuration (e.g., alternator, water pump, A/C). Always verify the correct part number for the specific accessory being serviced.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Mack RWS: