98 E320 Spark Plugs
 

I'm attempting to change the plugs in my 98 E320. I got the plugs through Phill at FASTLANE. I've removed the two easiest plug boots (finally) and can see that a regular plug socket can't be used to remove the plugs. I also see that there is a "thinwall" plug socket in the tool kit that came with this car. Is this thinwall socket what those of you who are changing your own plugs are using to perform this service? If so, how do you torque the plugs using this tool? If not, does Mercedes (or somebody) make a thinwall plug socket for this application? Also, how do you ever manage to get the boots off of the plugs in the back of the motor? This car just turned 100K. Thanks for any advice.

Dave M

I've never run into a problem with changing plugs on those engines as I do them quite often. I just use my standard 5/8 plug socket from snap on.

standard socket should work
 

Getting the wires off is quite a chore. Have patience, be careful and DO NOT resort to pliers or to pulling the wires themselves, you will pay for it with a new set of very expensive spark plug connectors. I usually remove the electrical boxes (that's as close as I get to the technical name) from the valve cover to get a bit more clearance. They are the square plastic junction boxes, if I recall they take a torx or hex to remove them. Good luck. Did I mention to have patience?

As enochbell suggested remove the coils to allow more room to work and take your time. I also used a regular spark plug socket. Hand tighten the new plugs. I used high temp anti-seeze on the spark plug threads and dielectric greese on the boots to avoid what you are going through the next time I have to replace my plugs.

What a day! After calling a local Mercedes dealership to see what their guys were using for a plug socket, and going from parts store to parts store looking for a thinwall, I discovered I already had one in my toolbox. It slipped right over the first plug I tried to pull. Man, are they ever tight. It scares me a little because I've broken a plug in a dodge pickup I had once had. I've gotten four boots loose, but I'm still fighting the ones toward the back of the motor. When you remove the coil packs from the cam covers, do you unplug the HT leads at the coil pack, first? Also, do you know the (ft/lb) torque setting on the plugs? I got the anti-seize and the di-electric grease ready to go for the re-install. Now, all I need is the time. Thanks for all the help, so far.

Dave M