Changing Spark Plugs on an ML320

[Woolybear]

Hello:

I'm new to this forum so please pardon my seemingly basic questions. I've worked on cars for years professionally but, other than for maintenance on my own vehicles not very recently, and never on an MB engine.

My wife has a 1998 ML320 6 cyl. which is in need of new spark plugs which I'd like to replace for her. I've been told that on some models of MBs the plug wires screw on to the plugs. In attempting to check on whether or not that is true for this model I found that I could not easily (by hand) remove the plug wire from the plug. The wire has a metal cap where it attaches to the plug which appears to be able to accept some sort of tool. Being somewhat reluctant to attempt to "muscle them off" I thought it best to check with those that know more.

Can anyone tell me:

1. Are the wires on this model screwed on to the plugs, pushed, or something else?
2. Is a special tool needed or recommended to make the job easier?
3. In reading some of the other posts, for some models it was recommended for people that never did this before that some assistance (a mentor) might be required. Is this one of those models (maybe I should have asked this question first)?
4. Do I need to know anything else before I undertake this effort?

Thanks

[tgmiller77]

If you have changed spark plugs before then it is not much different. 12 plugs and some of them are in tight spots. I have done the job twice on E320s it just takes a few hours. Be sure to get the proper Bosch Platin plugs. The best tool for removing the spark plug boots is a 17mm open end wrench. Moving a few of the coil packs out of the way is necessary but simple.
Just take your time, don't cross thread the plugs and make sure you get the boots fully seated on the new plugs.
Wires push on and pull off nothing fancy.

[azinn]

Originally Posted by Woolybear

Hello:

I'm new to this forum so please pardon my seemingly basic questions. I've worked on cars for years professionally but, other than for maintenance on my own vehicles not very recently, and never on an MB engine.

My wife has a 1998 ML320 6 cyl. which is in need of new spark plugs which I'd like to replace for her. I've been told that on some models of MBs the plug wires screw on to the plugs. In attempting to check on whether or not that is true for this model I found that I could not easily (by hand) remove the plug wire from the plug. The wire has a metal cap where it attaches to the plug which appears to be able to accept some sort of tool. Being somewhat reluctant to attempt to "muscle them off" I thought it best to check with those that know more.

Can anyone tell me:

1. Are the wires on this model screwed on to the plugs, pushed, or something else?
2. Is a special tool needed or recommended to make the job easier?
3. In reading some of the other posts, for some models it was recommended for people that never did this before that some assistance (a mentor) might be required. Is this one of those models (maybe I should have asked this question first)?
4. Do I need to know anything else before I undertake this effort?

Thanks

This link should help -
http://www.keysolutions.com/M-Class.nsf/Home?OpenFrameSet&Frame=Main&Src=%2FM-Class.nsf%2Faac7d56ca8fd884b852563be00610639%2Fb8a89966a39517fc85256e1800137e98%3FOpenDocument%26Aut oFramed

[lkchris]

Originally Posted by Woolybear

I've been told that on some models of MBs the plug wires screw on to the plugs.

You've been told wrong. Perhaps in the 1950s.

Check the Mercedes tech lit for these and you'll find the special tool recommended for snapping the plug connectors off the plugs. It's basically an offset open end 17mm wrench the techs will have in their collection for adjusting valves on another engine.

BTW, last time I checked, plug wires for these engines were $24 each from Mercedes (list). That means a set is 12X24 = $288 so be careful with the wires. This was a couple years ago and with the economy what it is I'd guess the cost at maybe $36 now.

Here are the special tools:

http://www.startekinfo.de/etools/content/tool.jsp?toolno=110 589 01 01 00

http://www.startekinfo.de/etools/content/tool.jsp?toolno=112 589 01 09 00

Also, you'll probably have to remove some intake stuff from the right side--check to be sure you don't require outside torx sockets for some of this.

[Woolybear]

Thanks all for your help and advise.