Purchasing a used Mercedes SL350 can be an excellent way to experience luxury and performance at a more accessible price point. However, like any used vehicle, it’s crucial to conduct thorough checks to ensure you’re making a sound investment. This guide highlights key areas to inspect on a 2018 Mercedes Sl350 before you buy, helping you avoid potential pitfalls and enjoy your roadster with confidence.
Key Inspection Points for a Used 2018 Mercedes SL350
When examining a 2018 Mercedes SL350, focus on these critical systems and components known to sometimes present issues in this model range:
1. ABC (Active Body Control) Suspension System
Alt text: Close-up of a Mercedes-Benz ABC suspension strut, highlighting potential areas for leaks and damage.
The Active Body Control (ABC) suspension is a standout feature of the SL350, offering exceptional ride quality and handling when functioning correctly. However, it’s also a complex hydraulic system requiring careful inspection:
- Struts and Hydraulic Pipes: Visually inspect all ABC struts and hydraulic lines for any signs of leaks or misting. These are common failure points and can lead to costly repairs.
- Fluid Condition: Check the ABC fluid reservoir. The fluid should be green. Brown or black fluid indicates degradation and potential system problems.
- Ride Height: Ensure the car sits level at all four corners. Uneven ride height can signal issues with the ABC system.
- Operational Test: Thoroughly test the ABC system by raising and lowering the car multiple times using the in-car controls. The movement should be smooth and without unusual noises.
2. SBC (Sensotronic Brake Control) System
Alt text: Illustration of Mercedes-Benz Sensotronic Brake Control (SBC) system components, emphasizing brake functionality and the hold feature.
The Sensotronic Brake Control (SBC) system is another advanced feature. While less problematic than ABC, it still warrants checking:
- Brake Functionality: Confirm that the brakes operate effectively and smoothly.
- Hold Function: Test the brake hold function to ensure it engages and releases correctly. This is a standard feature and its malfunction can indicate an SBC issue. Note: While comprehensive SBC diagnostics typically require specialized equipment, these basic checks can reveal obvious problems.
3. Retractable Roof Operation
Alt text: Mercedes-Benz SL350 with its retractable hardtop roof in mid-operation, demonstrating smooth movement.
The SL350’s convertible hardtop is a key selling point. Its operation needs to be flawless:
- Smooth Operation: Cycle the roof mechanism fully, both opening and closing, several times. Listen for any grinding, clicking, or jerky movements that could suggest mechanical issues.
- Seal Inspection: Visually inspect the roof seals for damage or wear, which could lead to water leaks.
4. Water Drains – Crucial for Preventing Electrical Issues
Alt text: Diagram showing critical water drain locations on a Mercedes-Benz SL, including air box drain and rear window drains.
Blocked water drains are a common cause of problems in Mercedes SL models, leading to water ingress and electrical malfunctions:
- Air Box Drain (Passenger Side): Locate and check the drain in the passenger side air box under the bonnet vent. Blockages here can lead to water accumulating inside the car, often manifesting as damp carpets on the passenger side and potentially causing electrical issues.
- Rear Window Drains: Inspect the two drains located either side and below the rear window. Blocked rear drains can result in water in the boot (trunk).
- Boot/Trunk Area: Check for dampness or water in the boot, especially under the floor and around the PSE pump (Pneumatic System Equipment) located in the boot. Wetness here can indicate blocked drains or a leaking boot seal.
- PSE Pump Sponge: If accessible, check the sponge surrounding the PSE pump for dampness. A wet sponge is a strong indicator of water ingress.
5. Electrical System and Battery Age
Alt text: Interior view of a Mercedes-Benz SL350, focusing on the dashboard and center console electrical controls.
A thorough check of all electrical functions is essential:
- Functionality Check: Test every electrical component, including windows, lights, infotainment system, seat adjustments, and all dashboard controls.
- Consumer Battery Age: Locate and check the date code on the consumer battery in the boot. A battery older than 5-7 years, especially in a 2018 model which might have its original battery, might be nearing the end of its lifespan and could require replacement soon.
6. Engine Balance Shaft (Potential Issue in Earlier Models)
While less common in a 2018 model, it’s wise to be aware of potential engine issues:
- Balance Shaft Concerns: Earlier models of the SL350 (pre-2008/9) were known for balance shaft issues. While a 2018 model is less likely to suffer from this, inquire about engine history and listen for any unusual noises from the engine, especially during startup and idle.
7. Fuel Tank Baffle Rattle
Alt text: Underside view of a Mercedes-Benz, indicating the general location of the fuel tank.
An unusual noise from the fuel tank can indicate a specific problem:
- Metallic Rattle: Listen for a metallic rattling noise coming from the fuel tank area, particularly when the fuel level is low. This can be caused by a broken baffle inside the tank. While not a critical fault, it can be an annoying issue to rectify.
8. Wind Deflector
Alt text: Mercedes-Benz SL350 showcasing the wind deflector in its raised position behind the seats.
The wind deflector is a valuable accessory for open-top driving:
- Wind Deflector Inclusion: Ensure the car includes the wind deflector. It significantly enhances comfort when driving with the top down. Replacements can be expensive (around £300).
Desirable Options to Look For
While inspecting the essentials, keep an eye out for these desirable optional extras that enhance the 2018 Mercedes SL350:
- Panoramic Roof: A highly sought-after feature providing a brighter and more open cabin experience.
- Bose Sound System: Offers a superior audio experience compared to the standard sound system.
- Parktronic (Front and Rear Parking Sensors): Extremely helpful for parking, especially in urban environments.
- Staggered 18″ Alloy Wheels: Larger, staggered wheels enhance the car’s aesthetics and handling.
- AMG Body Kit: Adds a sportier and more aggressive look to the SL350. While less common on the 350, it’s a desirable visual upgrade.
By diligently checking these points, you’ll be well-equipped to make an informed decision when purchasing a used 2018 Mercedes SL350, increasing your chances of driving away with a well-maintained and enjoyable vehicle.
