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Submitted byCategoryChassis
Public
Ken K. Yee
on 01/11/2004 at 03:32 AM
DIYW163
How do you change the spark plugs?

According to Gilly on ShopForum, it's a fairly simple thing to do except you need an old M110 engine valve adjusting wrench to get the wires off the spark plug. It's an open end 17mm wrench that you use on a groove in the metal end, then you can pry it against the valve cover to lever off the plug wires from the plugs. Works pretty slick. A normal 17mm open end won't work, this tool has a pretty deep offset and aloows you to get in there:

HAZET Valve Adjustment Wrench for M110 engine.
p/n 110 589 01 01 00



randyman on mbworld/benzworld posted this helpful guide:

Tools that I used...


From left to right: WD-40, 17 mm open/closed wrench, Torx screw driver, 5/8" Spark Plug Socket, 3/8" short extension, 3/8" Ratchet, and Torque wrench.




1. Make sure the engine is cold! Proceed by taking off the engine cover -- just pry it out, and the Air box (undo the 8 clips).


Engine cover




Air box



2. After removal of the engine cover, you will see the 3 coil packs on either side of the engine (6 total). Use a torx screw driver to remove them (each pack is held by just one screw). After that, go ahead and unclip the packs from the harness.




Do one side first (I did the driver's side 1st). I sprayed WD-40 on the metal spark plug boots for ease of removal. Once that is done, use a 17 mm open wrench to pry them off.


Passenger's side view. The 17 mm wrench should fit nicely around the boot.




Give the wrench a good push and the boot should come off


Make sure that you don't mix the orientation of the plug wires from the coil pack! Do the plugs and wires one at a time so as not mess up which wire goes where. Or you can label each wire if it's better for you.


3. Once the boot is off, use the spark plug socket/extension/ratchet to remove the spark plug.


Remember: "Lefty loosey, Righty tighty"




Ye olde spark plug


4. Install the new plugs. Use anti-seize on the plug's thread if you wish. This'll make the removal easier the next time you do it again.


Brand new Platinum plugs.


5. Hand tighten the plugs in. If you have a Torque wrench, torque them to 15-20 ft-lbs afterwards. Otherwise, just tighten it about another 3/4 turn with the ratchet (DO NOT overtighten!).


Torque wrench in action.


6. Before installing the plug wire, spray the inside of the boot with some WD-40. This will make it a lot easier to put the boots back. Make sure that the boots "snap" back in. Double check by pulling the boot by hand -- if it comes off, push it in harder.

7. Just keep doing the same procedure to each plug. It gets harder as you go towards the firewall -- not enough room!

8. Once all the plugs are replaced, go ahead and screw the coil packs back and clip them back to the harness -- don't worry about mixing them up since each harness are "properly" positioned...as long as you didn't take the whole coil pack off.

9. That's it! It took me about 1.5 hours to do the job and picture taking. Put everything back together.




Miscellaneous:
* Expect to get some scratches on your hands and arms.

* Make sure that you don't drop anything in the engine bay! It'll be a PITA to reach in and get it.

* When spraying WD-40, you might get some on the headers. When you start the car it'll smoke, but don't worry the smoke will go away once the WD-40 fully evaporates.

* Do this at your own risk. I will not be responsible for any engine failure or any bodily harm.

* Expect more scratches on your hands and arms after a good hand wash.

* Feel free to add more info to this write-up if I missed anything.



From carson356 on shopforum on replacing the spark plug wires:
I think you could DIY, the only trick is using a 17mm wrench to remove the wire ends. Bremi is what mercedes uses and my source says if you buy 12 of 112-150-01-18 they will be long enough to fit all, I would recommend using the plugs mercedes recommends. The +4 is a good plug, I however have never used it in this application. The MB part number you need is 003-159-66-03-26 which is the same plug as the Bosch F 8 DPP 332.

From arkie on shopforum:
I just changed mine this past weekend, the ones that I took out were made by Beru (OEM, as it even had the star printed on the plug). Beru is not well-represented in the USA, so Bosch is your closest thing. The original plug is platinum and platinum should be used as the wires are resistor wires (2 Kohm according to the wire boot). I used the Bosch platinum +2 plugs that are $3.98 each at any of the major auto chains. The NGK's sounded good, but at $10 each I couldn't see getting them. The plug job is easy, mine weren't seized but took a good amount of torque to remove even after the initial loosening. The trick is to do it on a STONE COLD engine. I think some of the people who have problems with spark plug seizure try taking them out on a hot engine. I bought a set of KD spark plug wire pliers (the really nice stamped steel pair) and was able to easily remove all twelve wires without a hitch. I did the job this way:

Starting on driver's side of engine first, unhook the primary side of the three coils and swing the harness back out of the way. Next, remove the wires from the coils (still leaving them attached to the plugs) making sure to use a twisting motion initially. Remove the 3 T30 bolts from the coils and remove the coils. Lay the coils out in the order removed (not that it is critical, but I like keeping it straight in case I find anything funky with the plugs) and use your pliers mentioned above to remove the wires (again starting with a twisting motion). Standard 3/8" ratchet, 3" extension (although a 4" would have been nicer), and usual spark plug socket will get all of the plugs. Remove plugs and replace. Put everything back on that side. The passenger's side side is the same except you will need to take the top of the airfilter box loose and out of the way. I actually went a step further and took the bottom out, it is held in place by rubber bushings underneath but was tricky to take out and put back in. Entire job took my two hours, working at a leisurely pace. $75 for plugs, extra tools, and a box of ArmorAll rags for cleaning the interior of the ML was much better than $225 quoted by indie shop.



From blueeagle289 on Shopforum:

I finally got into a spark plug change on an ML320 and thought the experience might be worth adding to the large group of comments on that subject. This was the second plug change on this car. To summarize:

I used all the tools mentioned in other threads and then some. These included the normal wrenches and sockets and other attachments, PLUS a pair of curved needle nosed pliers and a short length of pipe to use as an extension of the ratchet handle. That became necessary on 4 or 5 of the plugs -- which were firmly seized in the block and took tremendous leverage to start them out of the "socket" in the block. The short length of pipe provided that leverage handily.

I used the curved needle noses to help pull off the metal plug boots, which were very tight. By carefully inserting one side of the needle nose pliers into the outer end of the boot, it was possible to exert significant pulling force on them in some cases and remove them. I also used the 17mm open end wrench and a wire removal tool with padded jaws -- that wasn't too sturdy as it turned out.

I did not remove fender liners or the bottom of the air filter module, etc. I simply took off the top engine cover and the top of the air filter module, moving the air intake up out of the way and tying it up slightly with nylon cord.

I then simply disconnected the coil modules from the harness and removed the coil module bolts; then pulled the metal boots off the plugs, placing the coil modules with wires attached near the car in their respective sequence for reinstallation. The driver's side was more difficult in terms of access to the boots themselves (less room to get at them). Do it first and the job remainder will be easier!!

All in all, it was not an extremely difficult DIY job, with the exception of those cantankerous metal boots -- which were very tightly ensconced around the plugs. The rest of the job, tight spark plugs included, was fairly straight forward.

I installed Bosch +4's, putting a little dielectric paste in each boot and some anti-seize on the plug threads.

I hope this helps others who plan to do this job and recommend the curved needle nose pliers for careful use on the metal boots, and a short piece of "leverage pipe" for the ratchet handle, in order to break lose the stubborn plugs you may encounter.




From Graham Challis:

It's not that bad once you realize that the coils on the driver's side need to come off first. I used a plug lead remover from Lisle tools to get the boots off the plugs:
http://www.lislecorp.com/tool_detail.cfm?detail=934

I think MAC and Snap-On also have similar grips - it makes the job much easier and reduces the skinned knuckles! I used a plug socket, universal joint and a 6" extension on a 1/2" ratchet. The coil units can also be taken off with a 5mm allen wrench. I put the Bosch +4's in, used anti-seize on the threads as well, plus permatex blue threadlocker on the coil units.




From timf on ShopForum:
1. The hardest part imho is getting the covers of the spark plugs - here's a tip which helped me.
When using a 17mm open ended spanner to pry off the spark plug covers, make sure you counter balance the leverage you're applying to ensure the cover comes off in line with the plug. Otherwise there's a tendency to push down on the cover which actually makes it very hard to remove. Also I gave the covers a slight tweak to rotate them a little first before attempting to lever them off.

2. When doing the drivers side make sure you cover the top of the exhaust heat shield - it has a very sharp edge and will cut your hands.



From Graham Challis:
For the sparkplugs, it's handy to have a variable angle set of pliers/grippers so that you can get the plug leads off - they can be a real PITA. I used these: http://www.lislecorp.com/tool_detail.cfm?detail=934

Apart from that it's fairly easy with a socket wrench with an extension and universal joint attachment. Good idea to put anti-seize compound on the threads seeing as they'll be there for the next 100,000 miles!




From WolfWinter on Benzworld:
WD40 is your friend doing this job. Before pulling the wire I soaked the plug with it and let it sit for a couple of minutes. I was able pull some of the plugs by hand.
After pulling the plug I sprayed the inside and outside of the plug and wire, makes it easier for the re-install and cleans them nicely.
The 17mm wrench is a must for this job.
The heat shield on the driver side (fuse box) is like a sushi knife. I ended up ripping an old t-shirt and stuffing it over the shield after I cut myself pretty bad. All you have to do is touch the sides and it will slice a good chunk of your hand.




From 43sqd on Benzworld:

Yes they are very difficult to remove but they have a special designed tool to aid in removal. Go to ebay and search for the "Benz Spark Plug Wire Remover Wrench" offered by KNK Tools; it's made by JTC model J-1308 and looks like this:


Another bit of advise, go to an automotive store (like Pep Boys) and purchase a tube of Silicone Boot Grease. After you remove the wires from the spark plugs apply a small amount of the grease to a cotton swab and spread the grease on the inside of the boot and then put it back on the spark plug. This will make the wire very easy to remove the next time you have to.




The correct gap for the MB spark plugs is 0.032


AC_ML posted the WIS page on this:
 


From Ard on Benzworld:

Difficulty: moderate

(only because of the sheer amazing amount of force needed to remove the spark plugs - which gave me fits of self doubt: "WAIT, I didn't miss some advisory about them using left-handed threads on this car...". You almost have to put aside your [perceived] knowledge about fastening torque and aluminum heads)

Also, I removed the left tire and fender liner to get better access - others have reported not needing to do so.

Tools:
* floor jack
* jack stand
* tire iron
* T-30 Torx bit
* 10 mm socket
* 5/8 deep-well sparkplug socket
* ratchet (swivel-head preferable) and extension
* torque wrench
* phillips screwdriver
* 17mm wrench (I did NOT use the Hazet wrench others have referred to, just a standard open wrench)
* masking tape

Steps:
--------
1) jack left front tire up and place jack stand under car (being sure rear wheels are chocked, transmission in park, etc.), and remove left front tire

2) unscrew 6 nuts holding the left fender liner. If you have fender moldings installed, remove the 4 screws holding the molding, and remove the attached clips. Now remove the fender liner - no need to remove the fender molding (if applicable)

3) unscrew 3 10mm nuts holding the heat shield above the manifold in place, and remove the heat shield

4) remove plastic engine cover from top of engine

5) remove engine air filter box by unclipping air intake tube (to manifold), and box cover, then removing air filter, and finally the bottom part of the box. The bottom of the box is NOT held in by screws, so you need to give it a firm tug

6) now pry off the spark plug boots with the 17mm wrench, using the manifolds on the left and right as a fulcrum - others have reported using a piece of wood to get additional leverage. Be careful not to damage the boots, in particular note that the metal part of the boot has a ridge running along it. Note that the 2 wires for each respective cylinder are labelled A and B. Although both the coils and the head have clear labelling, I prefered an additional visual hint and wrapped the bottom of each "A" boot with a piece of masking tape. For the passenger side, I was able pry the boots off from the top, whereas for the driver's side, I accessed the boots from the left wheel well.

7) Unbolt the 6 T-30 Torx screws holding the 6 coil packs (3 left, 3 right) in place and move the coil packs and attached plug wires out of the way - this facilitates access to the plugs

8) Unbolt each spark plug using the deep-well socket and ratchet - NOTE: the factory-installed plugs are AMAZINGLY tight - I'd like to hear from others (DIYs and Pros) whether this is common. I changed the plugs with the engine cold - perhaps that's part of the problem?

9) NOTE: I do not intend to start a flame war - on the installation I do some things that may or may not be commonly accepted. I am always happy to hear differing opinions, but FWIW, this is how I do it.

Check plug gap and gap new spark plugs to 1.0mm (if you are using the Bosch plugs sold on FastLane, they come pre-gapped at 1.0 mm)

Lube threads of new spark plugs with antiseize compound, and lube ceramic body of new spark plug with dielectric grease

Screw each plug in finger-tight, then tighten with torque wrench to 25Nm

10) reattach coil packs, and put a dab of dielectric grease inside each spark plug boot

11) reconnect boot to respective plug (remembering "A" vs. "B"), making sure the boot "snaps" on - don't forget to remove the masking tape from the boots if you used that to keep track of "A" vs. "B"

12) reinstall air filer box and reconnect intake hose

13) reattach heat shield

14) reattach fender liner (and fender molding if applicable)

15) snap plastic engine cover in place

16) reattach left front wheel, being sure to torque lug bolts to proper specs

Done.



From sunedog on shopforum:

I changed plugs over the weekend. Took about 30 minutes of prep (check gap, anti-seize threads, dielectric both ends of each plug wire) and about 90 minutes to do the R&R. Thanks for the excellent write ups in this forum. My experience:

1) I was really surprised how deep the plugs fit into the side of the block. It's like a Hemi. I wasn't expecting to be working mostly by feel. But didn't run into any problems.

2) I read in multiple places a 17 mm wrench is used to pop the wires off the plugs. I checked and a 17 mm wrench may have worked but it did not fit around the metal shaft of the wire. I used an 18 mm. It fit perfectly.

3) I did not remove a wheel or inner fender. I did remove all coil packs as I went and removed the air box to do the passenger side.

4) I wasted about 20 minutes chasing a new plug I dropped into the nether regions of the engine compartment. Got smart and stuffed an old bath towel in the gap between the engine and inner fender. The towel trick saved me twice after that.

5) I bought Beru wires (part number ZEF 1442 and 300.891.442 on the box) and I have a concern for the next plug change in 100K miles. Look at the image. The old plug wire is on top. The new Beru is on bottom. The Beru has much less metal and no lip to grab onto. The only thing you see when they're installed is the rubber part of the connector. Not sure how I'll get those baby's off in four years. Hopefully the dielectric will enable me (or future owner) to pop them off by hand. I may proactively pop them off and re-seat them every six months or so (if I can remember to).



Notice also my old plug with right at 100K miles on it. The center electrode is worn to a nub. The gap probably opened from 1.00 mm to 2.00 mm. Amazingly, the truck ran smoothly with the old plugs. Wife needs to give me some gas numbers from before and after so I can see if it made a difference in mileage. But this is still hard evidence you should change them AT LEAST every 100K miles.




From 2002ml320 on Benzworld:

I was told that the wires should be Bremi or Beru to ensure factory quality. I found those for $200. Then I was told the factory plug is a Bosch part# FR8DPP33. I also ordered these online for $4.71 each. I wanted to use the Bosch 2's but I was told not to. I am not sure how accurate that is but why take a chance. Could not find or order the plugs from Autozone or Advance Auto they both said they could not get them. So in total it cost me about $260 in parts incl S&H. WHAT A DIFFERENCE.

Here are some pointers as I just finished the project. Took me 2.5 hours.

+ First two steps: Make sure engine is COLD!
- Take off engine cover. Just pops off by lifting up from front
- Remove top of air filter box 6 clips on box and 2 clips on hose

+ ML320 is a 6 cylinder but it has
TWO PLUGS PER CYLINDER so you need 12 plugs and the ignition wire set comes with 12 wires.

+ Start the with passenger side much easier. Learning curve is fast and once you do 2 plugs and wires it will go faster. You DONT want to learn on the driver's side.

+ Wear gloves or your hands will get cut up. Especially on the drivers side from the heat shield

+ You DO NOT have to take off the coil packs on the passenger side as long as you have an extension long enough to get into the cylinder and clear the coil packs.

+ I found it easier to pull the wires off the coil packs with the coil packs
STILL ATTACHED to the engine block. You can get more leverage... use pliers. I actually found this to be the hardest part.

+ Tools needed: Pliers, Spark Plug tool 5/8" w/extension(s) 2.5" & 5", and Torx #T30, some WD-40 or plug grease will help the wires pop on easier. A flashlight will also help but not necc.

+ I found that having different size extensions small 2.5" and medium 5" was very helpful b/c the spaces to get the plugs are different on each cylinder due to hoses and other engine parts.

+ On the drivers side remove coil packs after popping off old wires and then connect all new wires.

+ You really dont need to do one at a time as I have read on other posts. You will notice that each coil pack is labeled A & B for each wire.... AS IS the cylinder. So really as long as you can read A & B you will know where each wire needs to go. I needed a flashlight to actually read the lettering. Without it I could not see A & B.

+ Out of the 12 wires 4 are longer. These are for the two cylinders closest to the windshield. 2 on driver side and 2 on passenger side. The other 8 wires are all the same length.


From 43sqd on Benzworld:

Get yourself a tube of dielectric grease, and with a Q-tip coat the inside of each end of every wire. Only use a small amount just to make it look wet. This will prevent the rubber from sticking to the porcelain on the plug and will aid removal in the future.



From Jeff968:
I replaced the plugs on my 02 ML320 and thanks to Randyman’s post on how to do the job and another poster’s input the job was a piece of cake. It took me just under 2 hours but I spent some time cleaning my wheels and wheelhouse. That is because I took the advise of another poster and approached the task from underneath. After removing the wheel and the wheelhouse the plugs were right there. It was straightforward. 7 plastic nuts hold the wheelhouse in place, then push it forward so it can clear the fender. Reverse for reinstall. I started with the passenger side which was very simple. I used the WD40 as Randy suggested and took my time and did them one by one. The driver’s side was a little more complicated as there was a heat shield staring at me when I removed the wheelhouse. However, I removed the three nuts and moved it to the side and there were the 6 plugs. The Power steering line was also present on the driver’s side but I got around it. The job was very straight-forward. With the rebate from Bosh on the plugs I only spent $36. The dealer quoted me $660 for the job. What a savings and no bruised knuckles either. I’ve attached a photo of what I saw on the driver’s side. Notice the heat shield pushed to the right. I couldn’t have done it without the help of the board and Randy’s instructions and photos.




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