A Practical Guide to the 1998-2007 Audi A8 Quattro Accessory Drive Belt
Everything you need to know before replacing the accessory drive belt on your D2 or D3 generation Audi A8 Quattro.
- A squealing noise on an A8 is often the fault of a bad tensioner or idler pulley, not just the belt. Replace them together.
- If the belt breaks, you will lose power steering and the engine can overheat in minutes. Pull over immediately.
- There are no major recalls for this system; failure is typically due to age and wear.
- High-quality aftermarket brands like Continental, Gates, ACDelco, and Bando are reliable alternatives to expensive OEM parts.
Is Your Audi A8 Quattro's Accessory Belt Failing?
The accessory drive belt is a wear item. It lives in a hot engine bay and is under constant tension. Over time, the rubber will crack and wear out. Ignoring the signs of a bad belt can leave you stranded and could lead to more expensive repairs. When the belt fails, all the parts it powers stop working at once.
Symptoms of a Bad Accessory Drive Belt
Listen and look for these common signs that your belt, or a related part, needs to be replaced:
- Squealing or Chirping Noises: A high-pitched squeal is the most common symptom. This noise is often worse when you first start the car or when you turn on the air conditioning. It's caused by the belt slipping on the pulleys.
- Visible Damage: Open the hood and look at the belt. If you see cracks, frayed edges, missing pieces, or a shiny, glazed surface, it needs to be replaced immediately.
- Accessory Problems: If your power steering feels heavy, your A/C isn't cold, or the battery warning light comes on, the belt may be slipping or broken.
- Engine Overheating: If the belt drives your water pump, a failure will cause the engine to overheat very quickly. Pull over immediately if you see the temperature gauge rise.
Pro Tip: Check the Tensioner and Pulleys
A squealing noise on an A8 is often caused by a bad belt tensioner or idler pulley, not the belt itself. The tensioner keeps the belt tight, and the pulleys guide it. When their bearings fail, they can make noise or seize, which can shred a brand-new belt. It is highly recommended to replace the belt, tensioner, and any idler pulleys at the same time for a complete and lasting repair.
Choosing the Right Aftermarket Belt: OEM vs. Aftermarket
For a vehicle like the Audi A8, using a quality part is important. The original OEM belt is excellent but often expensive. High-quality aftermarket belts can provide the same performance for less money. Brands like Continental and Gates are often original suppliers to Audi, so their aftermarket products are a trusted choice.
The brands ACDelco and Bando are also available and are known to produce quality belts. Bando is a major OEM supplier for many Japanese carmakers, and ACDelco is the original parts brand for GM. While they are reliable, many Audi specialists and owners prefer to stick with European brands like Continental for the best compatibility and peace of mind.
Known Issues, Recalls, and Bulletins
As of early 2026, there are no specific recalls or Technical Service Bulletins (TSBs) from the NHTSA for the accessory drive belt system on the 1998-2007 Audi A8 Quattro. Any recalls found for this vehicle relate to other systems like airbags or the sunroof. Failures of the drive belt are almost always due to normal wear and tear or the failure of a related component like the tensioner.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Belt | $44.32 - $57.50 |
| New OEM Belt | $65 - $90 |
| Shop Labor | $120 - $250 |
| Total Aftermarket Repair (Belt, Tensioner, Labor) | $250 - $500 |
Frequently Asked Questions
Can I drive my A8 with a bad accessory belt?
No. If the belt is broken, the car will lose power steering, the battery will stop charging, and the engine may overheat in minutes. This can cause serious engine damage. You should stop the car immediately in a safe place.
Is replacing the accessory belt a DIY job?
For someone with mechanical skill and the right tools, yes. The process involves using a wrench to release the belt tensioner, removing the old belt, and routing the new one correctly. The engine bay on the A8 is tight, which can make it challenging. Always take a picture of the belt's routing before you remove it.
How often should the accessory belt be replaced?
There is no exact mileage. A safe practice is to have it inspected after 60,000 miles and replaced if it shows any signs of wear. Many mechanics recommend replacing it proactively between 80,000 and 100,000 miles to avoid being stranded.
What's the difference between an accessory belt and a timing belt?
They are two separate parts. The accessory belt is outside the engine and runs things like the alternator and power steering. The timing belt (or chain, in many A8s) is inside the engine and keeps the engine's internal parts moving in sync. A timing belt failure is catastrophic, while an accessory belt failure will just disable the car.
Technical Specifications
OEM Part Numbers: 077903137S
The accessory drive system on the 1998-2007 Audi A8 Quattro uses a single multi-rib (serpentine) belt. The belt is typically made from EPDM rubber and its length varies depending on the specific engine (e.g., 4.2L V8). The system includes a spring-loaded automatic tensioner and one or more idler pulleys to maintain tension and guide the belt.
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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.
- Audi A8 Quattro: