*Spark plug replacement for the M-Class (W-163)*

Tools that I used...

From left to right: WD-40, 17 mm open/closed wrench, Torx screw driver, 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.


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.



Cheers!

 

well done ... *CLAPS*

 

anybody know of any free sites that'll host my pics? imagestation is giving me a hard time.

 

here's another link --> http://www.mbnz.org/forums/forums/th...171331&posts=8 just in case the pics still don't show up.


hth.

 

Good job Randy. Saw your write up on BenzWorld also since they fixed their server problem.

 

thank you!

 

I know it's been two years from your post but it worked like a charm. It took me good three hours since I had to run Lowes to grab a star wrench (torx). Other than that it went smoothly!
My 2000 ML320 has 85K on it and it started having rough idles and lower MPGs. I ordered OEM platinum plugs from IMPORTECH for $82 (I believe they are in Texas) and they arrived in two days (California).
Driver side is so tight!
Kicked my dealer's #ss and saved bundle!

 

Hi all, due to these excelent instructions, I did mine today. Took about 2 Hours total because I messed up a part. I used Champion platinums (3.99 at O'reilly and they came ungapped. The gap was supposed to be 0.032 but I somehow got confused starting up and gapped them at 0.036. When I finished doing the passenger (easy)( side, and started working on driver side I realized the box says 0.032 and not 0.036 OH *****!

So I finished driver side and returned to pass which was a breeze - I did not even take the coils off this time.

Old plugs were probably original since the gap had come to 0.41 by now. All intake ones had oil on the threads. Exhaust ones had metal rust goo on the threads. Overall they were "working" but not properly

Engine came on strong like new!!!!!!! No CEL either! The idle stutter is gone as well that prompted me to replace the spark plugs.


I am surpized CEL reset itself immediately. WOW. Total cost $38 for plugs, $1.35 for cofee, Satisfaction of saving over $600 in stealer labor - priceless.

 

I did my ML500 about a year ago.

Things that surprised me: -
(a) there were 16 spark plugs. In my head was 1 per cylinder and so I was surprised at the parts department
(b) It didnt take long at all - compared to what the MB garage was quoting for time to do it.
(c) I spoke to my friendly MB tech and he can change 16 in 30 minutes !!

Things I learned: -
(1) If you use some 'thick' medical gloves they act like a second skin and you get less damage to your hands
(2) really, really, wait until the engine is cold

Richard

 

After the plugs I want to also replace the spark plug wires. I have no problem getting the plug side off using the wrench trick, but the harness side is very tight. Any tricks?

 

I just noticed today that those Bosch platinum plugs are $7.38 per pair at Wal Mart and I use 8 pairs! They only had seven on the rack!

P.S.-- The video thingie that helps you locate the proper plugs said very clearly "DO NOT GAP PLUGS"

 

Get them at NADA. I got 16 the other day @ $4.95 per.

 

Nice writeup!

Just changed the plugs on my parents ML430 this afternoon. Took me 3 hours...damn 16 plugs. Its crazy! Well, the extra time was due to the non existant room on the drivers side and non-cooperative boots.

The passenger side only took an hour to do. Then the drivers side was so damn tight and stubborn boots took forever to loosen up.

Nice scratches on my right arm, no deep cuts. Phew! Wore garden gloves so that helped a lot too.

Used Bosch platinum +2 plugs, car fired right up. Revs were nice and smooth, deep sounding exhaust. Sounds better than the stock original plugs. Car runs smoother and general acceleration is better too. The original plugs have 93k miles on them. Definitely doable for DIY but take your time and stubborn boots can be a b!tch.

 

Thanks for the great pictures! I just replaced the plugs on my 01 E430 4Matic using your pictures. 118,000 miles - plugs came out easily once the plug caps were removed.

The 17 mm wrench and WD40 tips made a big difference. It still took me 4.5 hours to do 16 plugs - the shop manual calls for 4 hours. Only ripped my thumb open once trying to remove a spark plug cap without the wrench - metal's stronger than skin. Couldn't get access with the torque wrench everywhere.

Next, I want to do shocks. Any pictures removing shocks on a 4Matic? I saw pictures for an E320 but I think the 4Matic may be more complicated.

 

Thanks for the DIY info. Just finished replacing the spark plugs on my ML320. Took me a little under 3 hours. Half of this time was spent trying to fish a torque screw and a ratchet extension out of the engine. I finally took off the front driver's side wheel and was able to get the screw. The extension is still under the fuse box. Anyone know how I can get to it safely? At any rate, your instructions made it easy. Dealer wanted $500+ to do the job. I spent $50 on Bosch Platinum 2 spark plugs at Wal-Mart and $20 on a torque wrench at Advanced Auto. And eventhough my wife just spent $400 shopping, I'm still ahead!

Thanks again for the info. By the way, not one scratch on my arms or any other part of my body.

 

Just replaced my spark plug on my C280 1999 & the picture that you took in replacing your spark plug was very helpfull. the only question that i had is how will i know if i did it right. i start the car & run it around the block & everything seems ok, the thing that worries me was the spark plug boot, i try very hard to put all the way,but its very hard coz of the space.

 

Don't use WD-40 for lubricating the boots. Use silicone grease, they make a type specially for spark plug boots and it is available at all auto parts stores. Also, use NGK or Bosch plugs. They have the highest dielectric constant in the ceramic insulator. that is the resistance of the insulator against the voltage. Lower DEC, more leakage of voltage through the insulator and less spark. Don't use champion or AC. Autolite is the best american plug. Platinum or Iridium is mandatory.

 

Thank you randyman,

the torx is a T30, I had hard time getting just that. End up buying one from Sears.
I went with Bosch +4 4418 from pepp boys cost me $7 x 12 piece.
besides that, everything went according to randyman's instruction. took me about 1 hour and 30 minute to do my first spark plug change on my ml320. it just dont have enought space to pry the wire off with a 17mm wrench. and a few cuts on my arms but its all worth it.

 

Thanks for all the instructions. It gave me the confidence to go ahead and replaced the spark plugs.

I bought the Bosch IR Fusion +4 from Autohaus Arizona at $6.45 each with total of $103.20. I will be applying for the Bosch Rebate of $2.00 per plug for a total of $32.00 as the max.

I was careful with not dropping anything on the driver side BUT I did drop a spark plug and I was shouting at my mistake #@#$%^&**. It did take some time to fish it out by using a painter's blue tape wrapped around a long metal rod.

Everything went faster after that and I got the engine started again and engine at idle is much more smoother. Mileage also increased.

I used a special

I did take the advice of buying a repairman's gloves.

What was very useful was the Stanley Extendable 3/8"drive rachet that can extend to 14" for better leverage when unscrewing the spark plugs and can retract so you can use it for tight spaces. The other nice thing about it is that the head can flex to different positions.


Independent dealer quoted me $450.00 for labor and that was with the discount applied. Regular dealer $600.00 for labor.

Thanks again!

 

mcphere:

did the plugs come pre-gapped or did you have to gap it?

 

just ordered plugs from autohauz, and checked my toolbox for the proper tools. Looks like a trip to lowes is in order. I have small hands. Will this make it easier or harder. I'm pretty good with DIY projects if I have good instructions. Is this doable for a woman?

 

Small hands should help, get a set of surgical disposable gloves, will stop you cutting hands when the wrench slips (which for me it always does).

Richard

 

Great Write up I'm going with NGK iridium plugs

 

Something very important to note here is when using tools not ment for the job you have to have the skills so you don't break stuff. I used the open end wrench and I didn't get the angle right the first few times and was having a real hard time taking the boots off the spark plugs. I even broke one of the old spark plugs and was lucky to have broken the end of the plug that doesn't have the part where the socket goes to. I was still able to put a socket on it and take it off.
I finally realized all you have to do, whatever size wrench you are using (even a 3/4'' will do) is get the wrench exactly 90 degrees from the boot. In other words, if you have to put a lot of force on the wrench to pry out the boot you are not doing it right, it does not take much force at all. just technique.

 

Hi.
I'm going to replace the plugs on my 99 ML320, after 103k miles.
Does anyone know what size spark plug socket to use and also what size Torx?

Thanks.
Walt