SethP

Hi guys,

I'll be changing the plugs on my 2008 E550 once they arrive (went with the Bosch Platinum plugs that are the factory plugs).

I've seen in all the DIY guides that an offset wrench is highly recommended, but all those guides are for e320s/350s or E500s. I haven't seen anyone say that in the context of a w211 E550.
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Can anyone advise whether this tool is needed or will even fit or work?
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if you have first hand experience with w211 e550s and have used a tool, I'd love to see the tool you used.

Thanks!
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Roop94

I havent done anything to the car, it is a-z stock lol wondering If i should be changing the plugs on mine as well...?

rtbrjason

No special tools required. Need a T27 to remove the coils and a regular spark plug socket to pull the plugs. Advise doing it on a cold engine but other than that one of the easier plug changes I've ever done.

SethP

This isn't about stock vs oe, you're supposed to replace them at least every 100k miles.

Roop94

no i meant like nothing has been changed on it. It's at 130k atm. Wondering, what could be the concern for not changing the plugs? What would go wrong? low power output?

SethP

Worst case they seize up and you can't remove them.

marlinspike

The real worst case is the modern car systems are compensating for a miss that you would otherwise be noticing and you are killing the catalytic converter.

SethP

And this is what you call a thread hijack... 6 replies and only one are about my question.

bbirdwell

"Mercedes spark plug boot removal tool" in Google will bring up all you need to know. You want one of these. Made the job much easier on both of my V8 Mercedes.

Search for "Mercedes spark plug socket" also. This is also nice to have.

A calibrated torque wrench is nice; if not, after gasket contact, tighten additional rotation as noted on the spark plug packet.

Heck, so long as I'm here, I'll tell you to replace the spark plug wires also. Be advised the wires are of multiple lengths and part numbers! As you pull them off, lay them out on the floor, then match the new wire part number to the old and install in the correct location. Silicon (aka "dielectric" grease (only a thin film!) on the inside of the boots for spark plug and coil is also a good thing.

SethP

Thanks for the reply, I've seen those and the only thing that's holding me back is that the descriptions say it works on E-class models up to 2005. The engine in the 2006-2009 are a little different so I'm concerned it won't work. Meanwhile I can't find anyone anywhere that sells this tool that actually states that it will work on a 2008 E550.

gafitanu

A 17mm wrench worked very well on all my 16 plug boots. Actually the tool is a longer 17mm wrench with an offset.

kajtek1

Instead paying arm and leg for the "special tool" you can go on garage sale or fleemarket and buy 17mm or 5/8" ofset wrench for +- $1.
45 seconds with haksaw to cut it open and you are set for life.
I bought our E320 at 143k miles and having records about dealer maintenance, I simply assumed the plugs were changed at 100k.
Car pass CA smog test just fine. Only a year later I reread the records and the code I took for plugs was something else.
So finally at 156,000 miles I put new plugs and the old one were definitely original as center electrodes were gone.
I observe mpg very carefully and new plugs did absolutely 0 change.

Sydwayz

1) There are no "spark pug wires" on a W211 E550. There are 8 coils directly over the plugs. You don't even have to disconnect the wire harness to the coils.
2) You do not need ANY special tools, like boot removers, etc. etc.
It's literally one of the easiest spark plug jobs to do.
3) The majority of the people posting above have no idea what they are talking about regarding the W211 E550 and spark plugs.

3/8 ratchet
spark plug socket (small)
3" extension (give or take)
8" extension (give or take)
T27 (I think) socket
3/8 universal
Dielectric Grease

You will be done in 45 minutes TOPS. Give a slight tug on each of your coil wire harnesses. If any of them come loose off the coil, you may have to wrap a zip tie around the coil and the end of the plug, just to make sure they are secure.

SethP

Wow huge thanks. I also validated through other sources the tool everyone is thinking about isn't applicable to the w211 e550 but your detail provided a great deal of clarity.