Buying a car is a significant decision, and when I stumbled upon a 1999 Mercedes Sl500 at my Uncle Dave’s shop in New Hampshire, it sparked an idea. Visiting family with my Aunt Kate, the SL500, though needing some attention, was undeniably beautiful. The thought crossed my mind: if I’m getting a car, why not make it something truly special? This marked the beginning of my journey with a ’99 Mercedes SL500, a car that was a year older than me and had already clocked 121,000 miles. My approach was optimistic – any problems that arose, I would tackle them head-on.
Purchased with my hard-earned savings, I embarked on the long drive back home to Virginia. A stop in Massachusetts to see my Aunt Karen and Uncle Erik introduced the first challenge. The hydraulic system for the convertible top’s locking mechanism decided to express itself, spraying fluid. Quick thinking and some borrowed paper towels averted a bigger mess, thankfully sparing the carpet. Little did I know, this was just the prelude to a series of DIY repairs and intimate learning experiences with my ’99 Mercedes SL500.
Leaving Massachusetts, the engine began misfiring. At the time, I was unfamiliar with this symptom. The SL500, with its 16 spark plugs for eight cylinders, cleverly masked the issue by continuing to run, albeit not perfectly. Back home, curiosity piqued, I opened the hood to investigate the source of the check engine light that had illuminated my dashboard.
I sold the car, but the lessons remain. My ’99 Mercedes SL500 was my personal automotive university, transforming me from a novice to someone with considerable car repair knowledge.
Taking the SL500 to a local garage for code reading revealed a crucial insight: not all repair shops are equipped to handle older luxury vehicles like the ’99 Mercedes SL500. The technicians, accustomed to modern daily drivers, lacked the specific training for my car. Faced with this realization and concerned about potential costs, I chose to bring the car home and embrace the challenge of DIY repair.
Suspecting either the coil packs or spark plugs as the culprits for the engine misfire, I initiated a process of methodical testing. Swapping coil packs and repeatedly visiting AutoZone to read error codes became my routine. Through this iterative process of changing components and code checking, I pinpointed two non-firing spark plugs. Replacing all the spark plugs revitalized the engine, and the ’99 Mercedes SL500 ran smoothly, for a while at least.
My ownership also demanded attention to the fuel injectors – another demanding task. Initially, I attempted to replace just the O-rings, but achieving a perfect seal proved incredibly finicky. Ultimately, opting for new injectors complete with pre-installed O-rings was the solution. This fuel injector replacement was among my first serious car repairs, and the learning curve was steep. Reassembly often led to unexpected setbacks, like snapped bolts, one of which required professional drilling out – a less than ideal moment.
The convertible top hydraulics of the ’99 Mercedes SL500 presented another significant project. Rebuilding the hydraulic cylinders myself seemed like a cost-effective approach initially. While it did work temporarily, I soon learned why professional remanufactured parts are often the better long-term solution. The small seals, critical in the high-pressure hydraulic system, were challenging to install perfectly without specialized machinery. My DIY rebuild held for a while, but eventually, the pressure overwhelmed a line, and hydraulic fluid was spraying again. This led to finally investing in remanufactured pistons, a more reliable fix for the convertible top of the ’99 Mercedes SL500.
One fortunate aspect of buying the ’99 Mercedes SL500 was that it came with a hard top. This became invaluable when the soft top deteriorated rapidly, developing holes within months. Replacing the soft top was not financially feasible at the time, so on pleasant days, I would remove the hard top, enjoying the open-air experience and storing it safely in my parents’ garage.
Brake maintenance was another essential undertaking on the ’99 Mercedes SL500. Replacing both front and rear brakes included upgrading the rotors. This seemingly routine job turned into a struggle when a caliper pin seized. Despite forceful hammering, it wouldn’t budge. In a moment of slight desperation, I took the stubborn parts to a local Mercedes-Benz dealership. The service advisor’s reaction when I presented just the car parts, seeking assistance, was memorable. Surrounded by Mercedes owners dropping off their cars for full service, I was definitely the DIY outlier. However, the dealership proved helpful for major diagnostics on a couple of occasions. While I was committed to doing the repair work myself, their diagnostic expertise was invaluable in understanding the more complex issues of the ’99 Mercedes SL500.
A significant challenge arose with a substantial air leak from the intake manifold. Replacing the manifold was a major undertaking, requiring the removal of coil packs, spark plugs, and numerous vacuum lines. Remembering the precise order and connections during reassembly was daunting. The vacuum lines, in particular, were intimidating. However, the moment of truth arrived when I turned the ignition key after completing the manifold replacement. To my immense surprise and relief, the engine roared to life. During the test drive, I half-expected something to go wrong, given the complexity of the repair, but the ’99 Mercedes SL500 ran perfectly. It was a moment of significant accomplishment and boosted my confidence in tackling complex automotive repairs.
Even simpler tasks could present unexpected moments. When replacing the fuel filter, I neglected to depressurize the fuel system. The resulting spray of fuel to the face was an unforgettable, albeit unpleasant, learning experience.
Looking back, while I cherish the experience, I wouldn’t necessarily recommend a ’99 Mercedes SL500, or any complex project car, as a first vehicle, especially a Mercedes-Benz. The sophisticated computer systems in these cars add layers of complexity to repairs. There were periods where my efforts to keep the car running were directly proportional to my income. The escalating repair costs were the primary motivator for tackling DIY repairs – I simply couldn’t afford to have everything done professionally.
Despite selling the ’99 Mercedes SL500, I deeply value the skills and extensive car knowledge gained through this experience. I transitioned from automotive ignorance to a level of understanding I never anticipated. The process of repair itself became fascinating, and I immersed myself in learning everything about the SL and cars in general.
Now, the search for my next automotive adventure has begun. An old Triumph is tempting, though my 6’4″ frame might be a tight fit. Alternatively, a 5-speed 1992 Mercedes 300SL, in blue, would be a dream. My time with the ’99 Mercedes SL500 has undoubtedly shaped my automotive preferences and DIY repair capabilities for years to come.
