Changing the spark plugs on your Mercedes-Benz is not as difficult as you think. If you have the right tools, we will show you what you need, it is a straight forward task. This guide provides step by step instruction and video clips to help you on replacing the spark plugs.
While most spark plugs can last over 100,000 miles, it is recommended that you change the spark plugs more frequently than that for optimal performance and better fuel economy.
It will take you a couple of hours to change the spark plugs, maybe even longer if you are changing spark plugs on a Mercedes-Benz for the first time. In the end, you will have a smoother running engine, get better fuel economy and even get rid of that misfire or check engine light.
You can change the spark plugs on your Mercedes-Benz for under $80 and save hundreds compared to the typical quote of $300 – $500 at most auto repair shops. You don’t need to be a mechanic.
|Model:||E CLA SLK ML S-CLK CLS GL SL|
|Frequency:||Every 60,000 -100,000 miles|
Parts and Tools Needed to Replace the Spark Plugs on your Mercedes-Benz
Here is a list of all the parts that you will need. We have provided links to Amazon for all the parts that we use to make it easier for you if you need to purchase any parts.
Try to stay with the original equipment if at all possible. If you want your spark plugs to last longer and provide a better spark, our recommendation is to install iridium tipped spark plugs instead of the platinum. Mercedes-Benz cars are equied with two spark plugs per cylinder, including the E 320. ML 350, S 500, CLK 55 AMG. If you have a six cylinder engine, multiply that by two and that’s how many new spark plugs you need.
- 6 cylinder engine, you will need 12 .
- 8 cylinder engines, require 16.
- 12 cylinder engine, you will need 23.
Did you catch that? For a 12 cylinder engine, you won’t need 23 but 24 spark plugs. Just making sure you are staying awake.
You have several options such as iridium, platinum or copper when it comes to the material of the center core. Iridium spark plugs perform better but also are the most expensive. Copper plugs are the least expensive and will get the job done but don’t last as long. Below we have provided recommended brands for each type.
Iridium Spark Plugs
Iridium plugs tend to cost a little more, but if you decide to invest in your car, Bosh Iridium Spark Plugs work flawlessly on the Mercedes-Benz Engines. NGK Iridium and Denso Iridium also work great on Mercedes-Benz. While Bosch is the OEM plug for Mercedes-Benz cars, some AMG models are equipped with NGKs.
Platinum Spark Plugs
Most Mercedes-Benz cars since 1995 and after are powered by Bosch Platinium spark plugs. They are cheaper than iridium plugs and you will be staying with stock performance.
Cooper Spark Plug
The least expensive plugs, but they also don’t last that long. If you really wanted to go this route you can go for the Bosch F8DC4 copper plugs. These spark plugs have a heavy duty copper core center electrode for superior reliability. They have insulator design to help avoid current leakage and misfires. Make sure to gap these spark plug to 0.044
You could choose either one of these spark plugs. Just remember to order the correct quantity.
There is one tool that you must have to be able to change the spark plugs in your Mercedes-Benz. That is the Spark Plug Wire Remover Wrench Tool 17mm. You will need this tool to remove the ignition wire boot. We will show you in the video clip how to use this too.
In addition, you will need a
- 3/8 ratchet drive,
- spark plug socket set,
- 3/8″ drive extension set
- magnetic pickup tool.
- torx socket set and a
- torque wrench in ft-lb.
If you clink on any of the links above you will be redirected to the Amazon if you need to purchase any of them.
Step by step instructions on how to replace the spark plugs on your Mercedes-Benz
Step 1. Open hood
Prepare the area around your car. Make sure there is no object nearby where you can trip and fall. Next make sure to work on a cold engine. If the car was running right before, then wait an hour or so for the engine to cool down or your can burn your hands. Use a pair of gloves to protect your hands.
Step 2. Disconnect the battery
We recommend that you disconnect the battery before you start work. The battery is located in one these three places: the engine bay, under the rear seat or the trunk. Disconnect the negative battery cable only, no need to disconnect both terminals.
Step 3. Remove engine cover
You may be intimated by the engine cover that doesn’t allow you to see anything on the engine or where the spark plugs are but don’t be. The engine cover can be easily lifted up. It is not held in place with any bolts or screws. There are four clips that hold it in place, so go ahead and pull it up. The cover may look slightly different on your car but the principle is the same.
Step 5 Location of spark plugs and coils
Next, locate the spark plugs and coils. We will need to remove the coils to make it easy to access the spark plugs. Don’t worry it is easy. Here is a picture that shows all the spark plug coil location.
Step 6 Unplug ignition coil packs
Disconnect the electrical connector from the spark plug ignition coil. You can press on the plastic tab and pull the connector away from the ignition coil. The plastic connectors can break easily, so be careful. If it any them don’t panic, you can use zip ties around the connector when you install them.
Step 7 Remove ignition coil
It will be easier to remove the spark plug boots if you can move the ignition coils out of the way. Remove the bolt at the center of the ignition coil pack using a torx socket wrench.
Step 8 Remove ignition wire
Use the 17 mm special tool to remove the ignition coil wire. Note that the top ignition coil wire goes to the forward plug marked with an A, and the bottom ignition coil wire goes to the rear spark plug marked with a B.
Here is a clip that summarizes all these steps.
Step 9 Remove old plugs
Use the a socket, extension and a rachet to remove the old plugs. It will be difficult to see the spark plugs as there isn’t enough room for you to look at. The picture below is worth gold and is the best picture you will get of the spark plugs and where they are installed.
It will take a while to remove all the 12 , 16 or the 24 spark plugs depending on your application. It is a good idea to remove and install new plugs one at a time. Be careful not to drop anything inside the engine via the spark plug hole. You may want to use some anti-seize lubricant to put on the threads when you install the new plugs. If you have a magnetic pickup tool keep it around because you will need it.
Step 10 Install new plugs
Install new spark plugs one at a time. If you are installing copper spark plug make sure to gap them to 0.044 using aspark plug gauge.
Step 11 Torque spark plugs to 18 lb-lbs
Use a torque wrench such as the Tekton 3/8 torque wrench to tighten the spark plugs to to 18 ft-lb (~25 Nm) for engines 113.987/988/990/991. Most other engines require 21 ft-lb (~28 Nm) of torque . This is very significant, especially for the aluminum alloy head. You should avoid over tightening the new plugs to prevent damage to the threads. Also, don’t want to leave the spark plugs loose as it is important that they don’t allow any leakage during compression or even worse pop out and damage your car.
A helpful hint would be to remove the rubber plug insert in the spark plug socket when installing the new spark plugs, especially for the driver’s side since it’s a little tighter on that side. That way, the socket won’t become detached from the extension when removing the socket after installation. Suggestion by Bill A.
What are the best spark plugs for Mercedes-Benz?
We would recommend that you install the original equipment spark plug. If you do want to upgrade a good choice would be BOSCH Iridium Spark Plug for Mercedes-Benz.