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I'm installing new spark plugs (MB part # 004-159-81-03) on M278 engine. I've marked the open side of electrode position on the socket and after torquing to 23 N-m, the open side of electrode is about 90 degrees out from facing the fuel injector. Has anyone experienced this? Should i not worry about this if the torque is correct?
There's only one thread on the plug and in the head, so only one possible point of engagement when installing them. The threads on the plugs and in the heads are so accurately machined that if the torque is correct, the plugs automatically 'index' themselves. Don't worry about it; just get the torque correct.
The WIS bulletin is really just a marketing puff, to frighten ignorant people into fitting only MB plugs. The damage in the picture was probably caused by an incorrect spark plug; no surprise there. Use the correct plugs, though - Bosch ZR6SII3320. If you buy them in an MB box, they will have the same Bosch part number, a little blue MB logo, and a higher price...
Savage212...what are the front splitter and rear diffuser. Does the rear hang down further than stock?
They're on my car in the pictures above. Carbon fiber add ons front rear and sides. The rear is a little lower with the diffuser on. Not really low enough to hit anything that you wouldnt have hit with the stock rear parts. The front is super low and scrapes on everything. Lol.
There's only one thread on the plug and in the head, so only one possible point of engagement when installing them. The threads on the plugs and in the heads are so accurately machined that if the torque is correct, the plugs automatically 'index' themselves. Don't worry about it; just get the torque correct.
The WIS bulletin is really just a marketing puff, to frighten ignorant people into fitting only MB plugs. The damage in the picture was probably caused by an incorrect spark plug; no surprise there. Use the correct plugs, though - Bosch ZR6SII3320. If you buy them in an MB box, they will have the same Bosch part number, a little blue MB logo, and a higher price...
FALSE.
DO NOT listen to this guy or you may cost yourself an engine. The plugs are indeed indexed by torque
They're on my car in the pictures above. Carbon fiber add ons front rear and sides. The rear is a little lower with the diffuser on. Not really low enough to hit anything that you wouldnt have hit with the stock rear parts. The front is super low and scrapes on everything. Lol.
Sorry byroll01. What manufacturer are the front splitter, side and rear diffusor?
I know a lot of people are using techs to change their plugs and that may not be a bad idea on these engines.
Two warnings up front, the new plugs or any plugs installed must be Torqued to Mercedes spec to make sure the plug is indexed or MB says cylinder wall damage can occur. Second, removing the plug wires from the plugs is really hard no matter how strong you are Damaging the plug wires is easy during removal, so be prepared to replace a couple. The two plugs in the back of the engine next to the firewall are really tough and those are most likely to be damaged.
1) Remove air boxes and engine covers
2) remove large rubber coil fuel rail insulation and be careful to not break or drop the two plastic clips attached to them. Pic below shows large rubber coil insulator covers.
3) Remove all coil plugs and and go slow , so you do not crack the coil plug clips or locking tabs on the coil. Pic below shows coils with covers removed
Pic below shows short plug wires with hard plastic sheating on them. They have to be pulled straight out of the plug hole and room is very limited.
4) Remove two screws per each coil pack. Do not remove plug wire on the coil side but grip coil and plug and pull off the wire from plug side. Twist wire first and then pull. On plugs that lack room , you may have to use a open end wrench to pry wires or worst case, rip them off and replace with new wires Note: On Passenger side, it helps to remove the one screw and clip that holds a wiring harness over the spark plug area.
5) Remove old plus using 14mm socket.
6) Note: Stock plugs are gaped to about 32 thou and if you are adding mods or tuning your engine, then colder plugs are needed. Also a tighter gap helps under heavy boost.
7) Put a drop of engine oil on each plug thread before installing and then drop the plug in the hole. The plugs on this engine are pretty much self guided into the threads, so pretty easy to get them started.
8) follow reverse order and re-install all parts.
Tools needed are 1/4 drive ratchet, swivel and several size extensions.
Flat head screw driver, 2 x 3/8 drive 3" extensions and swivel, plus 3/8 ratchet and 14mm deep socket.
3/8" torque wrench
Spark plug gap tool
Di electric grease to put back on the plug wires , so next time they come off easier.
E8 torx socket
MB master tech told me 23NM torque setting for the plugs but double check the torque spec before torquing each plug.
Has anyone used a different brand of plug? Denso? Any issues?
If I had to do it again, I'd just buy the tool off eBay to pull the boots off. It saves a lot of messing about and time if any of them don't want to come off....
I'm attempting to change my spark plugs and just can't seem to get these little plugs off. They're the ones that connect to the coil, as indicate by the red circle here. Any special instructions on how to get them off?
Slide the gray tab out as far as it will go, then press down on it and push out the connector.
Thanks for the quick response. The gray tab comes out a little when pulled backward but pressing it down doesn't do anything. Am I just not pressing it down hard enough? I feel like if I give it any extra muscle, I may break the whole plug.
You probably wont break it and it does only come out a little bit, it kind of clicks out, pressing down on the tab lifts the part thats hold the connector to the coil. I would give it a good press and wiggle as you pull back on the connector.
I was able to pull the plugs off the coils but getting the coil and boot out as one piece has been unsuccessful. The coil part seems like it's about to break from the boot if I yank at it, being all filmsy. It's at a weird angle that provides no room for pulling. I tried the wire method mentioned by another poster but no success. Any other ideas?
Get ready to order some boots, there is a good chance they will break. The wire method was the only thing that was easy and actually worked for me. I used an old long mini usb cable, made a loop under the protruding plastic tab that's on the boot and pulled the crap out of it. Before I reinstalled my boots I added a very small amount of dielectric grease around the edge of the inner boot and now I can pull the boots off with my hand and minimal effort.
The official mercedes instruction does not say to use a boot puller on this engine, you are supposed to be able to pull it by hand which is true if there is grease on the lip of the boot. You can use a generic boot puller but you risk crushing the plastic boot if its really stuck in there. In my case a cable was the best option and its only a one time thing if you apply grease afterwards.
There is/was a boot puller available; I saw one on eBay, but I'd done the job by then - much swearing, loss of temper, broken plastic tabs on leads, and a couple of new leads - so I didn't buy it. It gave you something rigid to get a grip on. It was I think aftermarket, and does not seem to be there now. It was a kind of sleeve, open along most of one side, with a little lip all round at the open end, that pushed down the spark plug tunnel along the lead, and once in place the lip would catch the end of the boot and enable you to pull it off. The tool doesn't seem to be there now.
It's all very well saying that the grease on the leads makes it easy to pull them off, but after 40k miles that grease is just a memory, the tabs are very brittle and break easily, and the leads are rubber, so they stretch. If there was room to get a hand in and pull straight for a decent distance, it wouldn't be a problem, but there isn't, particularly on No.1 and No. 8 cylinders..
On my No.8 pot, I almost ran out of ideas. Eventually, in desperation, I locked a pair of Mole-Grips on the metal insert in the lead at the plug end, used a piece of pipe pushed over the mole-grips as a lever (vertical in the engine bay), and stretched a bungee cord across the engine bay to pull on the end of the lever. I went and got a beer then, and when I came back, the bungee cord had won the struggle. The lead was destroyed, of course, but they're cheap enough.
I tried replacing the plugs on my M157 (W218) today & I could not figure out how to get that last screw on the passenger side, closest to the firewall, out. It looks like its under part of the coil pack & angled so that you have no room because the side of the engine bay is right next to it. Any tips? TIA
It is pretty tight in there; as I recall, I used 1/4-inch drive sockets, with universal joint adapter and extensions when necessary, on the job, and one way or another managed to get everything out. The metric E sockets don't have to be a perfect fit to remove the bolts, so a bit of an angle on them will still work - they don't have to be a totally snug fit.
10-04-2018, 03:17 PM
Damaging the plug wires is easy during removal, so be prepared to replace a couple. The two plugs in the back of the engine next to the firewall are really tough and those are most likely to be damaged.
