1989 Mercedes Benz 560SL Workshop Service & Repair Manual

1989 Mercedes Benz 560SL V8-5.6L RWD Automatic FAQs: Troubleshooting, Maintenance & Repair Guide

• Why does my 1989 Mercedes-Benz 560SL (V8-5.6L) have an oil smell or noticeable leaks?

  Oil leaks are quite common on the M117 V8 engine in your 560SL due to its age. Often, a 'stinky oil smoke' comes from oil dripping onto the exhaust. Start by checking the valve cover gaskets. They tend to harden, and oil can seep out, sometimes looking like it's from the head gaskets. Also, examine the oil filler cap seal; a brittle one can let oil drool down the cam cover. Another spot to check is around the oil filter housing and cooler gaskets on the front driver's side of the engine. These rubber components just wear out over time, it seems.

• What should I do if the ABS warning light comes on in my 1989 Mercedes-Benz 560SL?

  If your ABS light illuminates, it's a good idea to check a few things first. Many times, the issue is simply dirty wheel speed sensors. There's one at each front wheel and another at the differential for the rear. Remove them carefully and clean off any accumulated brake dust or metallic particles. Also, inspect the Over-Voltage Protection (OVP) relay, typically found near the passenger footwell fuse block. Check its 10-amp fuse, and sometimes resoldering cracked connections on the relay itself can fix it. Don't forget to confirm your brake fluid level, too.

• Why isn't my 1989 Mercedes-Benz 560SL's climate control blowing cold air or directing air correctly?

  Climate control issues in an older 560SL can certainly be puzzling. If you're not getting cold air, first ensure your refrigerant level is adequate, as leaks from old seals are common. The monovalve, which controls hot water flow to the heater, is a frequent culprit; if it's stuck open, you'll get warm air. For issues with air not coming from the right vents, suspect a vacuum leak. The system uses vacuum actuators with rubber diaphragms that degrade over time, affecting vent flap operation. Sometimes just checking the main vacuum lines can help.

• What causes a ticking noise from the engine of my 1989 Mercedes-Benz 560SL, and what should I do?

  A ticking noise from your M117 V8 engine, especially at startup, often points to hydraulic lifter failure. Over time, these lifters can lose their ability to maintain proper valve clearance, leading to that characteristic tick. It's also a strong indicator that you should have your timing chain and its guide rails inspected. The plastic guides are known to become brittle and fail, which could lead to much more serious engine damage if not addressed. Getting these checked promptly by a specialist mechanic is really important for the health of your 560SL.

• How can I improve the 'rumbling' feeling or increased cabin resonance in my 1989 Mercedes-Benz 560SL?

  That 'rumbling' sensation, especially noticeable during startup or at certain RPMs, often comes from worn engine and transmission mounts. Over decades, the rubber in these mounts deteriorates, losing its ability to absorb vibrations. This means more road noise and engine resonance gets transferred directly into your 560SL's cabin. Inspecting these mounts for cracks, tears, or excessive sag is the first step. Replacing old, collapsed mounts with new ones can significantly improve your driving comfort and restore that smooth, quiet ride Mercedes-Benz is known for. It’s a worthwhile fix.