When a beautiful 1999 Mercedes Sl500 Roadster crossed my path at my Uncle Dave’s workshop in New Hampshire, it was hard to ignore. Despite needing some tender loving care, its classic lines and roadster allure were undeniable. The idea sparked: why not choose a car that stirs the soul? Even though this SL500 was a year older than myself and clocked 121,000 miles, the mindset was simple – tackle any issue as it arises and learn along the way.
Armed with hard-earned savings, the purchase was made, and the long drive back to Virginia began. A stopover in Massachusetts to see family was when the first sign of classic car ownership quirks appeared. The hydraulic system for the convertible top’s locking mechanism decided to introduce itself with a spray of fluid. Quick thinking and some paper towels averted a messy situation, thankfully sparing the carpets – a small mercy in a journey filled with learning curves.
Leaving Massachusetts, the engine started misfiring. Inexperienced at the time, the nuances of a misfire were unknown. This generation of SL500, with its 16 spark plugs across eight cylinders, masked the issue initially, allowing it to drive, albeit not perfectly. Back home, curiosity led to lifting the hood and a deeper dive into the engine bay, the starting point of a comprehensive DIY repair saga.
I sold the car but I miss it. I learned a lot of skills and a lot about cars. I went into this knowing nothing to now knowing most of what you could know.
Seeking answers for the check engine light and misfire, a local garage visit ensued. This quickly highlighted a crucial lesson: modern garages aren’t always equipped for classic cars. The technicians, skilled in contemporary vehicles, lacked the specific expertise for this older Mercedes. Faced with this and escalating costs, the decision was made to embrace the DIY route.
The likely culprits for the misfire were narrowed down to coil packs or spark plugs. A process of elimination began, swapping coil packs, resetting codes, and frequent trips to AutoZone for code readings. This iterative process, though time-consuming, eventually pinpointed two non-firing sparks. Replacing all spark plugs provided temporary respite, and the SL500 drove smoothly, for a while.
Fuel injector replacement became another challenge during ownership, quickly escalating into a frustrating ordeal. Initially attempting to just replace the O-rings, the importance of a perfect seal became apparent. Ultimately, new injectors with pre-installed O-rings were the solution. This period was marked by broken bolts and stripped screws during reassembly, common pitfalls for DIY novices. One particularly memorable incident involved needing a screw professionally drilled out – a stark reminder of the learning curve.
The convertible top hydraulics, initially a minor leak, demanded more attention. A rebuild of the hydraulic cylinders seemed like a cost-effective solution compared to full replacement. While initially successful, the limitations of DIY repairs on precision components soon emerged. The pressure within the system proved too demanding for hand-installed seals. Hopes dwindled as a line popped, resulting in another hydraulic fluid leak. The eventual fix involved investing in remanufactured pistons, a more robust and reliable solution.
The SL500 came with a hardtop, a fortunate inclusion. As the soft top deteriorated rapidly, developing holes within months, the hardtop became essential. Daily driving took its toll, and finances weren’t immediately available for a new soft top. On pleasant days, the hardtop was removed, transforming the car back into a true roadster, and it was safely stored in the garage.
Brake work, both front and rear, was another necessary maintenance task. Upgrading the rotors introduced a new level of difficulty. A seized caliper pin refused to budge, even with brute force. A trip to the local Mercedes-Benz dealership became necessary, parts in hand. The contrast was stark: other Mercedes owners arrived in modern vehicles, dropping them off for service and leaving in loaners, while I presented a component needing urgent attention. Despite this, the dealership proved invaluable for major diagnostic assistance on a few occasions. While DIY repairs were preferred, professional diagnostics helped pinpoint the issues accurately.
An intake manifold leak presented a significant undertaking. Replacing the manifold was a complex job, requiring the removal of coil packs, spark plugs, and careful attention to vacuum lines and connections during reassembly. The fear of incorrect reconnection loomed large. However, upon completion, the engine roared to life on the first try – a surprising and rewarding moment of DIY success. The subsequent test drive, completed without any catastrophic engine failure, was a testament to perseverance and careful work.
A less successful repair moment involved the fuel filter. Forgetting to depressurize the fuel system resulted in a face full of gasoline – a messy but memorable lesson in automotive safety.
Reflecting on the experience, a 1999 Mercedes SL500 Roadster as a first car and project car is a bold choice, especially a Mercedes-Benz with its complex systems. The financial aspect became a balancing act, with repair costs often matching available funds. This financial reality was a primary driver for tackling repairs independently, learning and saving simultaneously.
I sold the car but I miss it. I learned a lot of skills and a lot about cars. I went into this knowing nothing to now knowing most of what you could know.
Ultimately, selling the SL500 was a practical decision, but the experience left a lasting impact. A wealth of automotive knowledge and repair skills were gained. The initial automotive ignorance transformed into a solid understanding of car mechanics, particularly for the SL model and classic cars in general. The journey ignited a passion for automotive repair and a desire for the next project. The search has already begun, with classic Triumphs and perhaps a 5-speed 1992 Mercedes 300SL in blue on blue on blue on the radar.
Liam Sullivan is a student at Virginia Commonwealth University studying exercise science.
Piston Car Stories, Preserving Car Culture
