Replacing spark plugs on an E39 5 Series BMW may seem like a daunting task, but with the right tools and a little patience, it can be accomplished in a few hours. This guide will provide you with step-by-step instructions and helpful tips to make the process as smooth as possible.
Before you begin, it’s important to gather the necessary tools. You will need a spark plug socket, a ratchet, a spark plug gap gauge, and a new set of spark plugs. Additionally, you may want to have a pair of gloves and a shop towel on hand. Once you have your tools and materials ready, you can begin the process of replacing the spark plugs.
The first step is to disconnect the negative battery terminal. This will help prevent any electrical shocks while you are working on the engine. Next, remove the engine cover and locate the spark plugs. They are typically located on the top of the engine, and they will have wires connected to them. Use the spark plug socket and ratchet to remove the old spark plugs. Be careful not to overtighten the new spark plugs, as this can damage the engine. Finally, reconnect the battery terminal and start the engine. If you have followed these steps correctly, your E39 5 Series BMW should be running smoothly with new spark plugs.
Safety Precautions
Changing spark plugs is a relatively simple task that can be completed in about an hour. However, there are several safety precautions that you should take before you begin:
- Disconnect the battery. This will prevent any electrical shocks.
- Allow the engine to cool down. This will prevent burns.
- Wear gloves. This will protect your hands from cuts and burns.
- Use caution when removing the spark plugs. They can be brittle and break easily.
- Do not overtighten the spark plugs. This can damage the cylinder head.
Additional Safety Tips
Here are some additional safety tips to keep in mind when changing spark plugs:
- Work in a well-ventilated area.
- Avoid touching the spark plugs with your bare hands.
- Use a spark plug socket wrench to remove and install the spark plugs.
- Inspect the spark plugs for damage before installing them.
- Replace the spark plugs according to the manufacturer’s recommendations.
Tools Required
Socket set
You will need a complete socket set to remove the spark plugs. The socket set should include sockets of various sizes, including a 16mm spark plug socket. A 6mm Allen key socket is also needed to remove the ignition coils.
Spark plug wrench
A spark plug wrench is a specialized tool used to remove and install spark plugs. It is designed to fit snugly around the spark plug, providing a secure grip for removal and installation.
Gap gauge
A gap gauge is used to measure the gap between the spark plug electrodes. The gap should be set to the manufacturer’s specifications, typically between 0.035 and 0.045 inches (0.89 and 1.14 mm).
Torque wrench
A torque wrench is used to tighten the spark plugs to the specified torque. The torque setting should be specified in the vehicle’s service manual, typically around 25 Nm (18 lb-ft) for BMW E39 5 Series engines.
Additional tools
In addition to the essential tools listed above, the following items may be helpful:
- New spark plugs
- Anti-seize compound
- Work gloves
- Shop rags
- Flashlight
Disconnecting the Battery
To ensure your safety when working on the spark plugs, it is crucial to disconnect the battery first. This simple step prevents any electrical shock or accidental ignition during the repair process. Here’s a step-by-step guide to safely disconnecting the battery:
1. Gather the necessary tools: You’ll need a 10mm wrench, a pair of insulated pliers, and a towel or rag.
2. Locate the battery: Open the hood and identify the battery, usually located in the engine bay towards the front of the vehicle.
3. Disconnect the negative terminal first: Using the 10mm wrench, carefully loosen the bolt connecting the negative terminal (marked with a “-” symbol) to the battery. Gently pull the terminal away from the battery post.
4. Wrap the negative terminal: Place the towel or rag over the disconnected negative terminal to prevent any accidental contact with the positive terminal.
5. Disconnect the positive terminal: Repeat step 3 for the positive terminal, which is typically marked with a “+” symbol.
6. Double-check connections: Ensure that both the negative and positive terminals are completely disconnected and no cables are making contact with the battery posts.
| Negative Terminal | Positive Terminal |
|---|---|
| Marked with “-“ | Marked with “+” |
| Disconnect first | Disconnect last |
| Wrap with towel or rag | Do not wrap or cover |
Removing the Engine Cover
1. Locate the engine cover on the front of the engine.
2. Find the rear edge of the cover and push down on the clips that hold it in place.
3. Slide the cover forward and lift it off the engine.
4. Disconnect the electrical connector that is attached to the back of the engine cover. This connector is for the oil level sensor.
| Front | Back | Connectors |
|---|---|---|
 |
 |
 |
The oil level sensor connector is a white connector with a single wire. It is located on the passenger side of the engine cover, near the front.
Once the electrical connector is disconnected, the engine cover can be removed completely.
Locating the Spark Plugs
The spark plugs on an E39 5 Series are located in the engine compartment, near the top of the cylinder head. They are covered by a plastic engine cover, which must be removed to access them.
To remove the engine cover, first locate the two plastic clips that hold it in place. The clips are located on the front and back of the cover. Once you have located the clips, use a flathead screwdriver to pry them out of place.
With the clips removed, you can now lift off the engine cover. Be careful not to damage the cover or the spark plugs.
Once the engine cover is removed, you will see the spark plugs. They are located in the center of each cylinder head.
The spark plugs are held in place by a single bolt. To remove a spark plug, first use a spark plug wrench to loosen the bolt. Once the bolt is loosened, you can pull the spark plug out of the cylinder head.
When removing the spark plugs, be careful not to drop them. If a spark plug is dropped, it can be damaged.
Here is a table summarizing the steps for locating the spark plugs:
| Step | Description |
|---|---|
| 1 | Locate the two plastic clips that hold the engine cover in place. |
| 2 | Use a flathead screwdriver to pry the clips out of place. |
| 3 | Lift off the engine cover. |
| 4 | Locate the spark plugs in the center of each cylinder head. |
| 5 | Use a spark plug wrench to loosen the bolt that holds the spark plug in place. |
| 6 | Pull the spark plug out of the cylinder head. |
Removing the Old Spark Plugs
Once you have access to the spark plugs, you can start removing the old ones. Here’s a step-by-step guide:
- Use a spark plug socket and ratchet: Attach a spark plug socket to a ratchet and carefully loosen the old spark plug by turning it counterclockwise.
- Remove by hand: Once the spark plug is loose, remove it by hand to prevent cross-threading.
- Inspect the old spark plug: Examine the condition of the old spark plug, including the electrodes, insulators, and threads. This can provide insights into any engine issues or maintenance needs.
- Clean the area: Before installing the new spark plugs, use a clean rag or compressed air to remove any dirt or debris from the spark plug wells.
Additional Tips for Removing Spark Plugs
- Use the correct tools: Ensure you have the correct spark plug socket and ratchet to avoid damaging the spark plugs or engine components.
- Be careful not to overtighten: Overtightening the spark plugs can damage the threads or strip the spark plug holes in the cylinder head.
- Replace all spark plugs at once: It’s recommended to replace all spark plugs simultaneously, even if only one has failed, to maintain consistent performance and prevent future issues.
- Avoid cross-threading: Be cautious when installing the new spark plugs and ensure you align them properly with the threads. Cross-threading can permanently damage the spark plug holes.
| Torque Specifications for E39 5 Series Spark Plugs | |
|---|---|
| Spark Plug Type | Torque (Nm) |
| Standard Spark Plug | 30 |
| Iridium Spark Plug | 23 |
Installing the New Spark Plugs
7. Apply Anti-Seize to the New Spark Plugs
The final step in preparing the new spark plugs is to apply anti-seize to their threads. This will help to prevent the plugs from seizing in the cylinder head and make them easier to remove in the future. When applying anti-seize, be sure to use a small amount and only apply it to the threads, not the electrode. Too much anti-seize can actually hinder the spark plug’s ability to create a strong spark. Here is a table summarizing the steps for applying anti-seize to spark plugs:
| Step | Description |
|---|---|
| 1 | Apply a small amount of anti-seize to the threads of the new spark plug. |
| 2 | Use your fingers to spread the anti-seize evenly over the threads, covering the entire surface. |
| 3 | Avoid getting any anti-seize on the electrode of the spark plug. |
Once the anti-seize has been applied, you are ready to install the new spark plugs in the cylinder head.
Reinstalling the Engine Cover
Once the spark plugs have been replaced, it’s time to reinstall the engine cover. Start by carefully aligning the cover over the engine, ensuring that the gasket is properly seated in the groove. Firmly press down on all sides of the cover to secure it.
Next, reconnect the ground cable by tightening the terminal nut. Double-check that the cable is securely connected.
Last but not least, inspect the oil filler cap to ensure it is properly tightened. A loose oil filler cap can lead to oil leaks or contamination. Once you’re satisfied with the cap’s tightness, reinstall the engine cover by placing it on top of the engine and securing it with the clips. Ensure that all clips are securely fastened to prevent the cover from becoming loose while driving.
Reconnecting the Battery
Once the spark plugs have been replaced, it’s time to reconnect the battery. Here are the steps to do it:
- Locate the battery: The battery is usually located in the engine bay, either in the front or the back of the car. It’s a black box with two terminals, one positive and one negative.
- Clean the battery terminals: Over time, the battery terminals can become corroded. This can prevent a good connection and lead to starting problems. Use a wire brush or sandpaper to clean the terminals.
- Reconnect the negative terminal: The negative terminal is usually black or has a negative sign (-). Reconnect this terminal first.
- Reconnect the positive terminal: The positive terminal is usually red or has a positive sign (+). Reconnect this terminal last.
- Tighten the terminals: Use a wrench to tighten the terminals securely. Don’t overtighten them, as this can damage the terminals.
- Check the battery connections: Double-check that the battery terminals are securely connected. Wiggle the terminals to make sure they’re tight.
- Reset the ECU (optional): Disconnecting the battery can reset the engine control unit (ECU). This can be helpful if the car is experiencing any problems after the spark plugs have been replaced.
- Start the car: Once the battery is reconnected, start the car and check for any problems.
- Test drive the car: Take the car for a short test drive to make sure it’s running properly.
Testing the Engine
Before replacing the spark plugs, it’s essential to test the engine. Start the vehicle and let it run for a few minutes until it reaches operating temperature. If the engine runs roughly, idles erratically, or exhibits hesitation, you may have a faulty spark plug. Use a spark plug tester to determine the culprit.
A spark plug tester is a simple tool that connects to the spark plug wire. When the engine is running, it will produce a spark that can be seen through the tester’s window. If the spark is weak or intermittent, you will need to replace the corresponding spark plug.
To test the spark plugs, follow these steps:
| Step | Instructions |
|---|---|
| 1 | Unplug the spark plug wire from the spark plug. |
| 2 | Insert the spark plug tester into the end of the spark plug wire. |
| 3 | Start the engine and observe the tester for a spark. |
| 4 | If the spark is not strong or intermittent, replace the spark plug. |
| 5 | Repeat the process for each spark plug. |
How to Change Spark Plugs on an E39 5 Series
Changing the spark plugs on an E39 5 Series is a relatively simple task that can be completed in about an hour. The following guide will provide you with step-by-step instructions on how to change the spark plugs on your E39 5 Series.
Materials needed
– New spark plugs
– 10mm socket wrench
– 16mm socket wrench
– Ratchet
– Extension bar
– Spark plug gap gauge
Instructions
1. Park the car on a level surface and turn off the engine.
2. Allow the engine to cool completely.
3. Open the hood and locate the spark plugs. The spark plugs are located on the top of the engine, under the valve cover.
4. Disconnect the electrical connectors from the spark plugs.
5. Use the 16mm socket wrench to remove the spark plugs.
6. Gap the new spark plugs to the correct specification. The correct gap specification can be found in your car’s owner’s manual.
7. Install the new spark plugs into the engine.
8. Tighten the spark plugs to the correct torque specification. The correct torque specification can be found in your car’s owner’s manual.
9. Reconnect the electrical connectors to the spark plugs.
10. Close the hood.
People Also Ask
How often should I change the spark plugs on my E39 5 Series?
The spark plugs on an E39 5 Series should be changed every 100,000 miles or 6 years, whichever comes first.
What are the symptoms of bad spark plugs?
The symptoms of bad spark plugs include:
– Engine misfire
– Poor acceleration
– Increased fuel consumption
– Rough idle
How much does it cost to change the spark plugs on an E39 5 Series?
The cost to change the spark plugs on an E39 5 Series varies depending on the labor rate of the mechanic. However, the parts themselves cost around $50 to $75.
