Replacing Fuel Injectors In A Mercedes 560Sl: Step-By-Step Guide

If you're looking to replace the fuel injectors in your Mercedes 560SL, you've come to the right place. This job is definitely doable as a DIY project, and you can source the parts you need from several online retailers. Fuel injectors are small valves that spray a fine mist of fuel into the combustion chamber, and over time they can become fouled, leading to decreased engine performance. By replacing them, you can improve combustion and fuel economy. You'll want to make sure you have the necessary tools and safety equipment, and it's recommended to replace the fuel lines as a complementary modification.

How to remove old fuel injectors

To remove the old fuel injectors from your Mercedes 560SL, you will need a 14mm open-end wrench and a 10mm socket wrench with a 6-inch extension. It is important to prioritise your safety by wearing safety glasses and work gloves, and ensuring that you dispose of all fluids in a safe manner.

First, use the 14mm open-end wrench to loosen and remove the fuel line which feeds the injector. These lines come directly from the fuel distributor and may contain residual fuel, so use a shop rag to absorb any spills.

Next, after the line has been removed, use the 10mm socket wrench to loosen and remove the flange which keeps the injector in place. Once the flange has been removed, the injector can be pulled out from the engine.

It is worth noting that the plastic/rubber seal should make a slight "click" when it seats properly around the injector. Additionally, the injector holders may come with a black rubber o-ring, but some people prefer to use green Viton o-rings, which may need to be ordered separately.

How to install new fuel injectors

To install new fuel injectors in your Mercedes 560SL, you will need the following tools: a 14mm open-end wrench, a 10mm socket wrench with a 6-inch extension, and safety equipment, including gloves and safety glasses. It is also important to wear protective clothing and to dispose of all fluids in a safe manner.

The fuel injectors are small valves that spray a fine mist of fuel into the combustion chamber. Over time, they can become fouled, resulting in an inefficient spray pattern, which leads to decreased engine performance.

• Loosen and remove the fuel line feeding the injector using a 14mm open-end wrench. These lines come directly from the fuel distributor, and there may be residual fuel in them, so use a shop rag to absorb any spilled fuel.
• After the fuel line is removed, use a 10mm socket wrench to loosen and remove the flange that keeps the injector in place.
• Once the flange is removed, carefully pull the injector out of the engine.
• Inspect the old injector for any signs of soot or build-up, which could indicate poor combustion, poor fuel, a timing issue, or contamination.
• Prepare the new fuel injector by removing any protective caps and installing the new seals. The seal should slide over the tip of the injector, and you may need to use a light coating of grease or soap to help it slide into place.
• Insert the new fuel injector into the engine, ensuring that the seal seats properly with a slight "click."
• Reattach the flange and fuel line using the appropriate wrenches, and ensure that all connections are tight and secure.

Remember to dispose of any old parts and fluids properly and to recycle whenever possible.

Fuel injector seal placement

When replacing the fuel injectors in a Mercedes 560SL, it is important to wear safety glasses and work gloves, and to dispose of all fluids in a safe manner.

The first step is to loosen and remove the fuel line which feeds the injector using a 14mm open-end wrench. These lines come directly from the fuel distributor and may contain residual fuel, so use a shop rag to absorb any spills. Next, use a 10mm socket wrench to loosen and remove the flange which keeps the injector in place. Once the flange is removed, the injector can be pulled out of the engine.

Now, inspect the injector. If the injector has a build-up of soot, this indicates poor combustion over time, which could be due to poor fuel, a timing issue, or contamination. If you are installing a new injector, the white plastic caps will need to be removed. The rubber seal should slide over the tip of the injector and make a slight "click" when it seats properly. You can use a light coating of grease, motor oil, or dish soap to lubricate the seal and help it slide into place.

Finally, to reassemble, simply follow the steps in reverse.

Fuel injector parts to order

When it comes to fuel injector parts for your Mercedes 560SL, there are a few key components that you'll need to order to ensure a successful repair or replacement. Here's a detailed list of the parts you should consider:

Fuel Injectors

The fuel injectors themselves are the most crucial component. These are small valves that spray a fine mist of fuel into the combustion chamber. Over time, they can become fouled, resulting in an inefficient spray pattern, which leads to reduced engine performance. It is recommended to replace them with new ones to restore optimal fuel delivery and combustion.

Seals and Sleeves

Seals and sleeves are essential for ensuring a tight fit and preventing fuel leaks. Seals, such as O-rings, are used at various connection points in the fuel injection system, including between the injector and the fuel rail, and between the injector and the intake manifold. Sleeves are used in conjunction with seals to provide a secure and leak-proof connection.

Fuel Pressure Regulator

The fuel pressure regulator controls the fuel pressure in the system. It is responsible for maintaining the optimal fuel pressure required for efficient fuel injection. A faulty regulator can lead to either too much or too little fuel being delivered to the injectors, affecting engine performance.

Fuel Accumulator

The fuel accumulator stores a small amount of pressurised fuel to ensure that the fuel injectors have a consistent supply during transient conditions, such as rapid acceleration or deceleration. This component helps to smooth out fluctuations in fuel pressure, ensuring that the injectors receive a steady flow of fuel.

Fuel Injector Guide

The fuel injector guide helps to ensure the proper alignment and positioning of the fuel injectors. It acts as a mounting point and provides stability for the injectors, ensuring they remain securely in place during vehicle operation.

Cold Start Valve

The cold start valve assists with starting the engine when it is cold. During cold conditions, the engine requires a richer air-fuel mixture to start. The cold start valve helps to achieve this by providing additional fuel to the injectors until the engine reaches its optimal operating temperature.

When ordering fuel injector parts for your Mercedes 560SL, it is important to ensure compatibility with your specific vehicle model and year. Additionally, always refer to a trusted mechanic or repair manual for guidance on the exact parts required for your particular situation.

Safety precautions

Changing fuel injectors can be dangerous, so it is important to take precautions to ensure your safety. Here are some detailed safety measures to follow when changing the fuel injectors in your Mercedes 560SL:

Wear Protective Gear

Before starting, put on safety glasses and gloves. Protective gear will shield your eyes and skin from any harmful substances or debris. It is also recommended to wear long gloves and boots for additional protection.

Disconnect the Battery

Before you begin any work on the fuel injection system, disconnect the battery. This is an essential step to prevent any accidental electrical discharges or sparks, which could be dangerous when working with flammable fuel.

Let the Engine Cool

Allow the engine to cool down completely before starting work. A hot engine can cause burns and make the fuel injection system more volatile.

Have a Fire Extinguisher Handy

Keep a fire extinguisher nearby whenever you are working on the fuel system. This precaution is crucial as fuel is highly flammable, and you want to be prepared in case of a fire.

Relieve Fuel Pressure

Before removing any components, relieve the fuel pressure to prevent unexpected fuel spray. You can do this by pressing a valve on the fuel line or pulling the fuel pump relay and cranking the engine for a few seconds.

Work in a Clean Area

Choose a clean, well-ventilated workspace to avoid dirt and debris from contaminating your new fuel injector and fuel system. Contamination can cause issues with the fuel injection process and engine performance.

Dispose of Fluids Properly

When working with any fluids, such as engine oil or coolant, make sure to dispose of them safely and responsibly. Coolant, in particular, is poisonous and should be treated as such. Keep it away from children and pets, and never pour it down the drain.

Use Jack Stands and Wheel Chocks

If you need to jack up your car, use jack stands and chock your wheels. Engage the parking brake as well to prevent the car from moving unexpectedly.

Disconnect the Electrical System

If you are working with the electrical system, always disconnect the battery first. This will prevent any accidental electrical discharges, which could be hazardous when working in tight spaces with sensitive components.

Be Mindful of High-Temperature Water

Be cautious of the engine cooling system, as it can reach very high temperatures. If the injector sleeve pulls free during maintenance, high-temperature water could escape under pressure and cause severe scalding. Consider isolating the engine cooling system before starting work.

Follow Manufacturer's Instructions

Refer to your Mercedes 560SL's manual for specific instructions and safety precautions. The manufacturer's instructions are designed with your safety in mind, so it is important to adhere to them closely.

Don't Work Beyond Your Ability

If at any point you feel that the task is beyond your ability or comfort level, stop and seek professional help. It is always better to be safe than sorry when dealing with complex automotive systems.

Frequently asked questions