I don't think us W211 owners have a spark plug change tutorial on our own so I decided to write up one with pics!

Step 1
Grab a beer or two, this is going to take you at least 1hr and a half

You will need the following tools seen in this picture


From left to Right:
-Mercedes Benz V6/V8 Spark Plug boot puller - Available on Ebay for less than $22 shipped
-Bosch Platinum Spark Plugs 12ea part number #7422/FR8DPP33 These are the updated plugs that are OEM in the car and will give you 100,000 miles, don't waste time and money fooling around with +4 or +2 plugs or other marketing gimmicks, its useless. These are available at the dealer for a whopping $12 or from online for as low as $4.37 from Rockauto.com
-3 inch Spark Plug Socket, 5/8 with 3/8 drive,
-3 inch extension 3/8 drive
-Typical Ratchet
-Folding Torx set for the T27 Torx screws on the coil packs, all of those items are available from your local Autozone.

Step 2

Open the hood and remove the intake manifold by first removing the front piece as shown in the above picture. Simply pull up and off at the same time.
Then locate the two front tabs holding the intake manifold in place and lift up on them, they will eventually pop up so you can remove the manifold, there are also two in the back so becarefull not to brake them.
Take the intake tubes off


Step 3

Here you can see the coilpacks for cylinder's 1-3 were going to start out on this side first.

Remove the three wire harness that power the coils so you can begin using the torx bit to take out the screws. A normal bit will not work here since it is not long enough and a normal screwdriver will not have the clearance

Step 4
Take the spark plug wires out using the Mercedes Spark plug puller (which is a 17mm open end wrench but with a dip at the end) You will need to move the coils around so you can grab the boot. Simply grab the end of the boot and push against the motor to take them off. Repeat this process until all the plugs are out and coils are off. One coil will have to stay as it is hooked into the wire harnesses.

Step 5

Grab the socket and feel around until it goes into the plug hold and grabs the spark plug, make sure its on there.
Take the 3" extension and hook it on the end of the socket like below:

Take the ratchet and hook that onto the extension, take off the plug by turning counter-clockwise (lefty loosey <-> righty tighty)
You can speed things up by unhooking the extension and ratchet and hand un-screwing the plugs once they become loose enough.

New plug next to old plug


Step 6
Put the new plug into the socket and you will simply reverse the way you took the old plug out by fitting it into its hold and hand tighten the plug before you attach the extension and ratchet to finish the job. I did not have a torque wrench so I just tightened it until it became hard to use 1 hand to tighten it.

1 down 11 more to go! Simply repeat this process for the rest of the plugs and the other side as well.

Step 7 putting it all back


Make sure you put the coils and plugs on back in the order they were taken off or you will have some serious misfires. Here's a helpful hint, when you hold take off the coils, put them in your trunk and line them up as they would be sitting on the engine. Notice the wire on the top always goes to the right hole and the bottom one always goes to the left hole.

DONE! Now put your intake manifold and tubes back on and go out for a drive and enjoy the new responsiveness and acceleration.

Most annoying part of this task was screwing in and out the T27 screws as on the driver side last bank there is a hose there that limits twist action.

 

i was thought to do one plug - one wire @ a time. you can never screw it up

 

Great write-up, but spark plugs need to be torqued to the proper spec as this impacts the plug's ability to transfer heat into the head.

BTW, you didn't mention using any anti-seize or dielectric grease for this job. Is there any reason why?

Regards,
paul...

 

Its been said on the forum bosch did not reccomend using anti sieze. You can do it one plug at a time as well I took them all off so I can knock them all out. I can feel how much the old plugs were torqued to I just felt for the same resistance

 

Good write-up!!! And great pics...

I need to replace my plugs. This is just the kinda DIY illustration I need.

 

Does anybody know the torque number?

I'm about 5k away from 100k, and I need to do this....

 

I believe its between 18-22Nm you can run em past 100k if tour not getting misfires

 

Paul I did use a small amout of antizeize on each plug. AND dielectric grease on the boot to make easier removal next time and easier installation.

I could not torque all my plugs due to wrench handle being too long so I used my wrist clicker on the correct torque. That was about 15,000 miles ago and all is well.

 

so what would be the benefit of replacing the coils too

 

@ my local stealership, I inquired about them doing this same job, 1200 dollars!

I didnt say much after I was told that. Although, I thought to myself 1200 for some wires & plugs.

wow!!

 

Hi Vettdvr,

Good hearing from you!! I did the same thing when I did my plugs, and it's really a hassle to get a torque wrench in there but I managed.

Although many of these "100K mile" plugs come with a coating to prevent them from seizing up, I have heard of cases where they did seize up when the plugs were left in at 100K (and above) miles.

BTW, my E320 has 110K miles on it now and a couple of months ago, the right rear spring broke (non-airmatic) so I had to replace that -- what a hassle. I realize that I should have replaced both springs, but I figured that my wife drives the car and she wouldn't have felt any difference (her commute is 10 miles roundtrip!).

Hope you're doing well and still flying!

Regards,
paul...

 

An entire set of Spark plug wires can be bought for $140 and Sprark plugs $60, save the grand in stealer profit and go to autozone/ebay and do it yourself This is a very easy task, only annoying part is the T27 screws coming out and in. Just be careful not to drop anything, its like a bottomless pit down there.

 

again, whats the benefit of changing the coils along w/ plugs - wires?

 

Not much. Coils will work fine, until they don't. Coils are replaced when they fail.

 

Nice well thought out write-up - I've received quotes all over the place but typically for spark plugs at an indy it's $700 vs. DIY $75 (only 53 if you have the special tool)!

If you DIY, I'm told if you don't use the 17mm offset wrench suggested in this DIY, it's super easy to tear the coil boot. Still on Ebay for 21.50 shipped!

Glad I waited to do this job until the right DIY came along.

BTW, the OEM bosch plugs are on sale at AutohausAZ for $4.47. Get 12 and you're over 50 bucks and UPS shipping is free. I literally ordered at 10am Monday and got them 5pm Tuesday, AZ to CA.

I do plan to use a torque wrench if I can, and on the Bosch Spark Plug box, it indicates torque spec at 21ft.lbs./28Nm.

 

Thanks again for the write-up. Just did the spark plug change this weekend. Here's my 2 cents on the experience.

1 - The 17mm offset wrench is extremely useful for removing the coils from the spark plugs. I also used the wrench to install the coils on the new plugs. I used a soft mallet for leverage only. I placed the wrench handle area against the mallet which was placed against the firewell next to and above the spark plug and levered the coil against the plug. You'll know it's seated right since it does take some force and then you'll hear a very muted thud indicating proper installation.

2 - If you use a 5/8" spark plug socket that is smallish (not sure how else to describe it), then you'll encounter the same problem I did which is not having enough space between the valve cover and the socket wrench to properly remove the spark plug. What worked for me was using one of those 3/8" articulating socket adapters.

3 - Proper torque specs and your torque wrench, dielectric grease for the coils and anti-seize for the plugs.

enjoy!

 

Ditto on #2, gotta use a 3" spark plug socket and a 3" extension with the 3/8 drive. Gave me perfect clearance for all 12

 

Great write up! I have one question for clarification. Do the Bosch plugs come gapped from the factory or do I need to gap them myself. If so, what is the gap?

I am a new MB owner and I have come to love the information available in here for the DIY individual.

Thanks in advance!

 

Sand320....

OE factory replacement pre gapped @ (.040 and/or1.0mm 0.039" +/-)I believe. I always double check for accuracy and torque to 20-30 Nm (15 - 22 ft.lb). Just replaced (2) weeks ago.

 

Thanks for the great info, I will tackle this myself when it comes times and save some serious cash. The dealer quoted $500 for the job.

 

just did this on my E500 16 plugs. i just followed the DIY, thanks DEXION for the great writeup, it was very helpful. i did use antiseize and the dieletric grease really helped on pushing the wires onto the plugs, especially towards the back of the engine where you have very limited space.. to me that was the worst part . all in all, wrench from ebay, 2 beers, 2 hours , all is good..

 

Fantastic post! I tackled this job in just under two hours with your help. I love the added pep from the new plugs. My e320 has 80k miles and original plugs from the previous owner. That's no way to treat your pride and joy.

Thanks for your help, Dexion!

 

Congradulations, Here's a You Tube link for the forum for future reference:

http://www.youtube.com/watch?v=qzCdqlpRN3g

 

Same process with the newer motors?

 

AutohausAZ only shows 6 plugs required per car for my 2006 E350 4Matic. I have to do mine in the spring so I'm not sure if that's correct (haven't pulled the engine shroud to see how many wires are coming from the coil packs). I did get the special wrench on ebay for $20 so I'm ready when it's time to do this.