JohnnyC

So here is a (work-in-progress) guide for removing the spark plug to your engine. This guide is also applicable to other Mercedes-Benz models such as the ML350, E350, C350, and GLE350.

Take precaution and use the proper tools to avoid damage to the engine. A broken spark plug will cause internal damage to the engine.

TOOLS REQUIRED:
• 1/4" drive torque wrench capable of 9nm / 80 in-lbs
• 3/8" drive torque wrench capable of 23nm / 204 in-lbs / 17 ft-lbs
• 14mm / 9/16" spark plug socket, 12 point
• Clic-R pliers
• Spark plug boot pliers or puller
• External Torx 8 socket
• External Torx 10 socket
• Torx 20 driver
• Torx 25 driver
• Torx 30 driver
• Long socket extensions
• Plastic trim tools

PARTS REQUIRED:
• Di-electric spark plug grease (Mercedes-Benz 002-989-80-51 / Versachem 15309 )
• Spark plugs (Bosch ZR6SII3320 / Mercedes-Benz 004-159-81-03)

OPTIONAL ITEMS:
• Upper air intake seals (276-141-01-80)
• Ignition coil packs (276-906-05-01)
• Vacuum with narrow hose
• Spark plug gap gauge
• Shop towels
• Magnetic retrieval tool
• Video borescope
• Cotton swab
• Fender liner
• Electrical contact cleaning spray
• Engine cleaning spray

STEP 1:
Ensure engine is off and key removed from ignition. Pull the red lever in the driver's footwell to release the engine cover. Set the engine cover to the vertical position and remove the first cover. I recommend doing this service while the engine has been deactivate for some time so yo avoid the thermal heat.


STEP 2: Disconnect battery using 10mm socket.

STEP 3:
Remove the engine cover (276-010-02-67).


STEP 4:
We need to remove the air filter box. If you have fender liners place them now to prevent scratching your paint. Remove the sensor, clic-clamp, two E10 bolts, and air nozzle clip. Then remove the rubber boot and lift the whole assembly out. Set aside the sensor.

STEP 4a:
Disconnect the ECU wires by pulling on the 2 opposing tabs. Use a plastic wedge tool to assist if the tab is difficult to release. The outward position is about 25mm or 1 inch away.




STEP 4b:
Remove the clips that hold down surrounding wires and lift the entire ECU unit straight up. You can see it is held in place by these four protrusions.

STEP 4c:
Remove this Torx 30 M6x1 - 14mm pan head screw and the bracket (276-150-37-73). Remove the cable harness clip if you have not done so previously.


STEP 5:
Remove the V6 plastic cover plate (276-141-00-21) by unscrewing the top two Torx 20 screws. Using your E10 socket with an extension, undo the two steel bolts inside the hole. They are recessed approximately 75mm / 3" deep, a magnet is recommended to retrieve them. Note that the mating insert appears to be a brass alloy, so be careful not to cross thread the insert.



STEP 6:
Remove the two E10 bolts in the back of the housing.


STEP 7:
Remove these two sensors near the back. They are different lengths and cannot be mixed up.



STEP ?:

STEP ?:


STEP ?:
So now you have the intake manifold off, plug each cylinder intake with clean plugs or towels.


STEP ?:
Undo the ignition coil connector by pulling the grey tab all the way out. Simultaneously press down on the grey tab and pull the connector out of place.

STEP ?:
Remove the two E8 bolts per ignition coil pack. Then using the spark plug boot pliers or puller, yank on the boot and you should hear a popping sound. Set aside.

STEP ?:
Extract the old spark plug using the provided 14mm socket and a ratchet. Take precaution when inserting the socket to prevent the ceramic breaking. When you are ready to remove the old spark plug out of the hole, ensure it is being securely held by the rubber ring, magnet, or spring clip depending on the type of socket you are using.

STEP ?:
Start the threads of the spark plug by your fingers only. Set torque wrench to 23nm or 17 ft-lbs and gradually reach target torque.


STEP ?:
Pack the greased ignition coil back into place. Start the E8 bolts then torque them to 9 nm / 80 in-lbs. It does not matter which bolt you torque first.

Ale Raineri

Tokkie

Thank you for the pdf. Excellent work! Much appreciated!

Steves40th

Outstanding write up. I now feel like I need a couple beers.. Not sure I want to tackle this job... How many hours for dealership to do this?

lkchris

This is an awful lot of work to install the wrong spark plugs.

i have no M276 engine experience, but know for certain that correct spark plugs for the M272/3 series engines are NOT available from Bosch in the USA aftermarket. Know that Bosch USA is a nearly completely separate company from Bosch Germany and seldom sells the same products. For spark plugs they seem to think Americans won’t install anything except resistor spark plugs (or maybe they are cheaper to produce). Mercedes did NOT install resistor plugs on the assembly line and the plugs sold by your Mercedes dealer are not resistor plugs either. It’s pretty suspicious to see the R included in the Bosch number listed in the write up. I’d compare that with the number on a factory or dealer plug. A different number is a different plug, and the R is the number difference when comparing M272/3 plugs and it wouldn’t surprise me if it’s the case regarding M276. It won’t break the bank to install the correct plugs

Steves40th

We were quoted 845 to replace the GLK 350s spark plugs.. thats just amazing..

chassis

Great post. Some questions

- Are the photos available anywhere else? They do not appear on my browser.
- Are the M276 3.5L naturally aspirated engine spark plugs torque + rotation specified? Or as the post above mentions, torque only? There is a 2014 QEC/EC Technical Update from John Dahlquist at Mercedes noting the importance of spark plug orientation for the M276, to avoid valve erosion.
- Can someone please post the WIS pages for spark plug replacement on this engine?
- Does anyone have a recent dealer cost they paid for spark plug replacement on this engine?

Thanks in advance.

JohnnyC

https://mbworld.org/forums/c-class-w...moval-diy.html

You torque it as the threads on both parts are timed. Dealer cost has been report to be around $700 to $800 USD

chassis

Thanks for the clarification. This is an excellent M276 3.5L NA spark plug change video from Senior Leigh. He posts on this site using a userid with all numbers.

https://en.leighsr.com/spark-plugs-replace-m276

formerjeepguy

I paid $350 to the dealer service center to get my plugs replaced on a 2015 GLK with the m276. Anyone paying $700-800 is getting ripped off.

JohnnyC

I was personally quoted $650 from my dealership in Los Angles years ago. That's when I decided to do it myself and save $$$.

Also having done the replacement about 4 times, I recommend the actually Mercedes-brand plugs instead of the Bosch ones. They are made by Bosch, but the spec is different.

purserg

How can I get the pictures that go with your post? Thanks

chassis

@purserg Look at this site:
https://en.leighsr.com/spark-plugs-replace-m276

Also look in the W166 section for my GLE 350 4MATIC ownership report. I did the M276 spark plugs last week.

JohnnyC

Sorry pictures got removed, there are alternative guides in this thread that equally as useful! If you have any question difficulties, feel free to reach out.

Maduro

I almost done mine (M278 engine - 2012 CLS550) but I can't for the life of me figure out how to reinstall and secure the wiring harness clips that go back into the top of the ignition coils. The grey tab is pulled all the way out, I insert the harness, and try to push the grey clip back again it'll either A not budge or B will snap back in but doesn't lock onto anything as I can simply pull the plug back out!

chassis

@Maduro Go slowly and don't force anything. Clean both sides of the coil wire connector and harness, then push the connector firmly and all the way into the coil. This should allow you to push the tab in and click or lock it. When pulled gently, the connector should not come off.

Maduro

Thanks for the reply, I swear I must've tried a half dozen times with some of these stubborn connectors. I'll try what you suggest though, I'll use some CRC Electronic Cleaner on both parts, some compressed air, and see if anything gives.

Maduro

Doesn't help. Upward pressure on the grey tab, downward pressure, pinching, wiggling, some grease etc etc nothing works. You'd think getting the coils/boots and plug themselves out of their sockets would be the toughest most time consuming part but no, for me I've wasted over an hour trying to get this clips to lock back in properly! Don't think I can go anymore slowly. Extremely frustrating,

WhathaveIdone

I agree, Struggled for two hours to get them off, ended up breaking the clips off, and still can get the connectors off. I put them all back. No new plugs for me this time.

JohnnyC

Squeeze the grey tab, then shove it back in.

Bay Leaf

At what mileage would the plugs need changing. I've got an SL350 with 34k on the clock. Will they need to come out at some point to check the gap etc.

NYCGLK

Check the service interval. There is no gap checking, you just replace them.

chassis

@Bay Leaf The 2017 maintenance booklet including the SL calls for replacement every 50k miles. The plugs are one time use items, because the crush washer is used to set plug orientation via installation torque. Once the crush washer has been deformed, it is not reusable. So gap can't be checked. It doesn't need to be checked.

Bay Leaf

Wow I've never heard of that before so thanks for the heads up. Is it just MB that adopts this or are other marques the same nowadays. It's quite a while since I replaced plugs (apart from the wife's Corsa) as my previous car was a diesel that I had for eleven years. So is the torque setting critical.

chassis

@Bay Leaf Mercedes specifies a torque setting, so in their eyes it is critical. I follow the manufacturer’s specifications. Buy a torque wrench if you don’t have one and plan to do the plugs. It’s far less than paying a dealer or an Indy.