The allure of a classic car is undeniable. For me, that allure took the form of a 1999 Mercedes-Benz SL500 I discovered at my Uncle Dave’s shop in New Hampshire. Visiting family with my Aunt Kate, I stumbled upon this beauty needing some tender loving care. Despite its age, a year older than myself and boasting 121,000 miles, its charm was irresistible. My mindset was simple: acquire this stunning machine, and tackle any challenges that arose. Little did I know, this decision would be the start of a profound learning experience in car repair and the unique ownership journey of a 1999 Mercedes.
Liam Sullivan
Having purchased the 1999 Mercedes SL500 with my savings, the long drive back home to Virginia commenced. A stop in Massachusetts to visit Aunt Karen and Uncle Erik marked an early sign of the adventures to come. The hydraulic system for the convertible top, a signature feature of the SL500, decided to announce itself with a fluid leak. Pistons controlling the top’s locks began spraying fluid, creating a mess quickly remedied with borrowed paper towels. Looking back, I was fortunate; despite numerous leaks during my ownership, the Mercedes’ carpet remained untouched.
Leaving Massachusetts, a new issue emerged – engine misfiring. Being unfamiliar with this symptom at the time, I pressed on. The robust V8 engine of the SL500, equipped with 16 spark plugs across its eight cylinders, allowed it to run, albeit roughly. Each cylinder still fired, masking the severity of the problem initially. Upon arriving home, curiosity led me to inspect under the hood, eager to understand the source of the newfound engine ailment in my 1999 Mercedes.
Seeking answers, I took the car to a local repair shop to decipher the check engine light codes. This experience offered a valuable early lesson: shops accustomed to modern daily drivers aren’t always equipped for the nuances of older, classic vehicles like a 1999 Mercedes. The technicians, while capable, lacked specific training for my car’s era. Combined with cost considerations, I opted to bring the SL500 home and embark on a journey of self-diagnosis and repair.
My initial diagnosis pointed towards either coil packs or spark plugs as the culprits behind the misfire. Employing a process of elimination, I began testing coil packs by swapping them and resetting the engine codes. Frequent trips to AutoZone followed, utilizing their code reading service to track the effects of my adjustments. This iterative process of changing components and code checking continued until I pinpointed two spark plugs that weren’t firing correctly. Replacing all spark plugs proved to be a significant step, and the 1999 Mercedes ran smoothly for a while thereafter.
However, the repair saga was far from over. Fuel injector replacement became another significant undertaking. Initially, I attempted to just replace the O-rings, but the precise seating required proved challenging. Ultimately, opting for new injectors with pre-installed O-rings became the solution. This task, like many others, was a first for me, and reassembly often brought new challenges, including broken bolts and screws. One instance required professionally drilling out a stubborn screw – a minor setback in the grand scheme of learning to maintain a 1999 Mercedes.
The convertible top hydraulics, initially leaking, demanded further attention. Attempting to rebuild the hydraulic cylinders myself seemed like a cost-effective solution. While cheaper, I soon learned why professional remanufacturing is often the better route. Rebuilding worked temporarily, but the small seals, difficult to install perfectly without specialized machinery, couldn’t withstand the high pressure. Hoping for the best, I started using the convertible top, but the pressure buildup eventually caused a line to pop, leading to another fluid spray. Finally, I conceded and installed professionally remanufactured pistons, resolving the issue properly.
The 1999 Mercedes SL500 came with a hardtop, a fortunate inclusion as the soft top deteriorated during my ownership. What began as a perfect soft top quickly developed holes within a few months of daily driving. To preserve it somewhat, I utilized the hardtop during inclement weather and only removed it on nice days, storing the soft top in my parents’ garage when possible.
Brake work, both front and rear, became another essential maintenance item. Upgrading the rotors presented a particularly stubborn challenge: a seized caliper pin. Despite forceful hammering, it wouldn’t budge. This impasse led me to a local Mercedes-Benz dealership, parts in hand, seeking assistance. The service staff and other Mercedes owners, accustomed to dropping off their cars for service and driving away in loaners, likely found my DIY approach and parts-counter visit somewhat unusual. Nevertheless, I utilized the dealership’s diagnostic expertise on a few occasions for major issues, preferring their insights to pinpoint problems before tackling the hands-on repairs myself on the 1999 Mercedes.
A significant air leak in the intake manifold presented another major repair. Replacing the manifold was a complex job, requiring disconnection of coil packs, spark plugs, and numerous vacuum lines – all while meticulously remembering their original positions for reassembly. The maze of vacuum lines was particularly daunting. Upon completing the reassembly, turning the ignition key and hearing the engine roar to life was a moment of immense satisfaction and surprise. During the test drive, expecting something to go wrong after such a complex repair performed for the first time, the engine performed flawlessly.
Even routine maintenance had its learning curves. Replacing the fuel filter resulted in an unexpected gasoline shower when I neglected to depressurize the fuel system – a vivid reminder of the importance of proper procedures.
Reflecting on my experience, I wouldn’t necessarily recommend a project car, especially a complex one like a 1999 Mercedes, as a first car. The intricate computer systems add layers of complexity to repairs. At times, it felt like I was working to fix the car just as quickly as I earned money for parts. This financial aspect was a primary motivator for undertaking the repairs myself; professional labor costs would have been prohibitive.
Despite eventually selling the 1999 Mercedes SL500, I genuinely miss it. The journey was an invaluable education in car mechanics, transforming me from automotive novice to someone with a solid understanding of car repair. My interest in the repair process itself blossomed, leading to deep dives into the specifics of the SL500 and automotive systems in general.
Looking ahead, the search for a new project car has already begun. A classic Triumph is tempting, though my height might be a limiting factor. Alternatively, a 5-speed 1992 Mercedes 300SL, in blue on blue on blue, holds significant appeal. The lessons learned from the 1999 Mercedes SL500 have undoubtedly shaped my future automotive aspirations.
