The 2004 Audi S4, a performance variant of the A4, is known for its powerful V8 engine and Quattro all-wheel-drive system. However, with age and complexity comes the potential for intricate repairs. In this post, we delve into a recent case at Pawlik Automotive in Vancouver, where a 2004 Audi S4 Avant presented with sudden engine issues. Join us as Bernie Pawlik, a seasoned auto repair expert, walks us through the diagnosis, repair process, and crucial insights into owning this generation of Audi S4.
Sudden Engine Roughness: The Initial Problem
A loyal client of Pawlik Automotive brought in their 2004 Audi S4 after experiencing a sudden onset of rough engine running. Without warning, the car began to perform erratically, prompting an immediate visit to the trusted Vancouver auto repair shop. This abrupt change in engine behavior was the starting point of a complex diagnostic journey.
Under the Hood of a Hot Rod: The 4.2L V8 Engine
The 2004 Audi S4 is equipped with a 4.2-liter V8 engine, a significant upgrade from the standard A4 models. Bernie Pawlik describes this engine as “shoehorned” into the engine compartment, emphasizing the tight packaging and complexity. While routine maintenance like spark plug replacement might be straightforward, most service procedures on this vehicle are notably challenging due to the confined space and intricate design.
Diagnosing the Misfire: Compression is Key
The diagnostic process began with a computer scan, revealing engine misfire codes across multiple cylinders. To pinpoint the issue, a compression test was performed. The results were telling: one cylinder, believed to be cylinder number two, showed no compression. This pointed to a serious internal engine problem, potentially involving valve or timing chain issues. At this stage, it was clear that engine removal and disassembly were necessary to uncover the root cause.
Engine Removal: A Labor-Intensive Process
Removing the engine from a 2004 Audi S4 is no small feat. As Bernie explains, accessing critical components like cylinder heads is virtually impossible without taking the engine out. The process involves removing the front bumper assembly and radiator components, a common procedure for extensive Audi repairs at Pawlik Automotive. In this case, complete removal was required.
The engine and transmission, along with the subframe, are dropped as a unit from underneath the vehicle. This is a time-consuming task demanding precision due to the tight tolerances and complex integration of components. Once removed, the engine and transmission are separated for further investigation.
Unveiling the Culprit: Broken Valve Spring
With the engine out and cylinder heads removed – another intricate task due to the elaborate timing chain mechanism – the problem was identified. A broken valve spring was the culprit, causing a valve to drop slightly and lose compression. Fortunately, the damage was minimal. The valve had just tapped the piston, averting a more catastrophic engine failure. Early detection and bringing the vehicle in promptly were key in preventing further damage.
Cylinder Head Overhaul: Addressing Potential Weaknesses
The cylinder head, with its five-valve design (three intake and two exhaust valves surrounding the spark plug), was sent to a machine shop for a complete overhaul. Crucially, all valve springs were replaced. Bernie emphasizes this proactive approach, stating, “you never know if one breaks when’s the next one going to go.” Reconditioning and resurfacing the heads ensured they were in optimal condition for reinstallation.
The Timing Chain Maze: A Known Achilles’ Heel
Bernie then addressed another well-known weak point of this 4.2L V8: the timing chain system. Located at the rear of the engine, between the engine and transmission, the timing chain assembly is incredibly complex. It features four timing chains, numerous guides, and tensioners.
Guide failure is common in these engines, leading to timing chain issues. In this repair, all guides and tensioners were replaced as preventative maintenance. While the chains themselves typically don’t wear, the plastic guides are prone to chipping and breaking down over time, potentially causing significant engine damage. Regular oil changes are critical to prolonging the life of these components, although Bernie notes that timing chain problems can still occur even with diligent maintenance due to the inherent design.
Addressing Fluid Leaks: Seals and O-rings
During disassembly, fluid seepage was noted from various engine seals. This led to the discovery of coolant and oil leaks originating from the front and bottom of the engine. The engine’s intricate casing, including the main bearing case, utilizes numerous seals and O-rings. With the engine already out, it was prudent to address these potential leak points. All affected seals and O-rings were replaced, requiring meticulous work and special sealant in certain areas. At 16 years old, seals and gaskets are prone to deterioration, making this preventative work essential.
Is Repairing a 2004 Audi S4 Worth It?
Given the extensive labor and cost involved in such a repair, the question of value arises. Bernie states that for the owner of this particular S4, the answer was yes. The owner loved the car and was committed to its upkeep. However, the decision is subjective and depends on individual factors like emotional attachment to the vehicle and financial considerations. Some owners may have a threshold beyond which repair costs outweigh the car’s value.
Smooth Performance Restored
Following the comprehensive repairs, the 2004 Audi S4 ran “really awesome.” The engine was smooth and powerful, with no fluid leaks. The repairs performed were not only reactive but also preventative, addressing common issues to enhance the vehicle’s long-term reliability. The naturally aspirated V8 provides a responsive and enjoyable driving experience, especially in the practical Avant wagon body style with Quattro all-wheel drive.
Buyer Beware: Considerations for Used 2004 Audi S4 Purchases
Bernie offers a word of caution to those considering purchasing a used 2004 Audi S4 with the V8 engine. Within the same week as this repair, another client with a newly acquired S4 experienced a catastrophic engine failure on a road trip. Diagnosis suggested a similar valve spring failure, leading to significant engine damage.
This highlights potential common issues with aging 4.2L V8 engines in these models:
- Timing Chain Failure: Guide and tensioner wear are well-documented problems.
- Valve Spring Failure: Emerging as another potential weakness due to age and fatigue.
Bernie advises that while these cars can be appealing, potential buyers should be aware of the risks of expensive repairs. He recommends caution when considering any high-performance or complex vehicle, emphasizing that thorough inspections and awareness of potential issues are crucial. While the 2004 Audi S4 offers a fantastic driving experience, prospective owners should factor in the potential for significant maintenance costs.
Vancouver’s Audi Repair Experts
For Audi owners in Vancouver seeking expert service and maintenance, Pawlik Automotive remains a top choice. With decades of experience and a commitment to quality, they provide reliable repairs and informed advice. To schedule an appointment, call Pawlik Automotive at (604) 327-7112. Visit pawlikautomotive.com for more information and explore their YouTube channel, Pawlik Auto Repair, for a wealth of automotive knowledge.
