A Journal of Project Cars: The Strategy To Restore My $925 Audi S4

Fortunately, the S4 started up smoothly and idled well with a new battery. Starting the engine is often a distant dream for some restoration projects, and although it had a coolant leak, I managed to get a glimpse of the powerful twin-turbo 2.7-liter V6’s sound for a brief moment.

Prioritizing the battery last time, the next issue became the coolant leak. By carefully listening to the engine during startup, idle, and light revving, I gathered more insights. Surprisingly, the engine sounded quiet and smooth, despite running on gasoline that had likely been sitting for several months. The real test will be when the engine is fully warmed up and under load, but that will have to wait until the cooling system is fully operational.

Next, I employed some detective-level analysis akin to Gil Grisham to delve deeper into the situation. Upon opening the trunk, I discovered a nearly full bottle of Mobil 1 0W-30, indicating potential oil consumption or leaks. It was evident that the previous owner did not pay much attention to using the correct viscosity. Nevertheless, I would prefer thin oil flowing through the small turbochargers’ passages than using oil drastically out of specifications like conventional Shell Rotella.

Following that, I equipped myself with a pair of nitrile gloves, grabbed my reliable floor jack, sturdy jack stands, and a powerful flashlight, ready for a detailed inspection.

I came across a discovery that the front suspension had been recently upgraded. There were new Bilstein B8s at the front, along with fresh suspension arms and bushings. This was a pleasant surprise and a welcome sight. Replacing all of that would have been costly. Checking the wheels for any movement by grabbing and rocking them revealed no issues with the wheel bearings. However, a torn outer CV boot was found in the front suspension, prompting me to order two new complete CV axles as a precaution.

Inspecting the Quattro sedan from underneath, supported safely, did not reveal any worrisome issues. While it was dirty, a brief cleanup only exposed undercoating, metal, and some minor seepage. California living has its perks.

A noticeable seepage was observed at the transmission pan—hence, I will procure a new gasket, filter, and a couple of bottles of ATF.

Heading towards the oil pan, it surprisingly appeared clean. However, some oil leakage down the driver’s side of the engine from certain oil lines hinted at a minor leak somewhere—further investigation is necessary.

The timing belt and its components form a complex system that can lead to potential issues. The recommended timing belt service interval for the B5 S4 is every 75,000 miles (most enthusiasts prefer not to exceed 60,000 miles), and accessing it requires removing several components. As a result, many opt to replace the thermostat and water pump during this service. The process involves removing the front bumper, radiator, and other parts without much ease.

If the timing belt was last replaced on time, it is definitely due for a replacement. The accessory belt is often replaced at the same time, and upon inspection, it showed a date code from early 2017. Regardless, these are critical items that require immediate attention. The last timing belt replacement remains uncertain.

Examining the rear suspension at the back of the S4’s chassis, it seemed to be in its original state. However, no signs of excessively worn or flexible bushings were found, so this area is not a top priority at the present moment. Additionally, the CV axles appeared to be in good condition without any tears, so monitoring them is advisable for now.

All the brake pads are nearly worn out, and the rotors are starting to develop a slight lip, necessitating the purchase of two sets of pads and four rotors. The power steering and brake fluid also require replacement.

To assess the condition of the paint and glass, I washed the car quickly using O’Reilly’s solution and a wash mitt, then dried it with some Mother’s Instant Detailer. A thorough buffing and paint correction are needed, especially on the roof where the clear coat is beginning to fade. Despite this, the car cleans up well, and I look forward to dedicating more energy to it.