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I’m undertaking the changing of plugs on my CLS550 and have reviewed prior posts on the process. It appears to be fairly straightforward but I’m unsure on the best tool for the removal of the spark plug wires to avoid damaging them. I’ve seen the official Mercedes tool, which looks like a long, bent wrench and have seen some other posts using wires or zip ties. I also see a large variety of tools available at the local auto parts stores so want to solicit advice on tools that you all have found useful and will fit in the tight spots.
Thanks Beer_Bandit. I have all of that, just looking for the best spark plug boot removal tool that can be used in that tight space.
I use long reach hose grip pliers. They're around 11 inches long. I try and grab the rubber boot as low as I can. Get at any good tool shop or maybe Amazon.
I couldn’t find a set of long reach hose grip pliers but really don’t see how those could fit anyway so after trying 90 degree long reach pliers to no avail, I went with the zip tie method. Looping long zip ties behind the plastic tab on the spark plug wires really gets a good grip on them and allows for a pretty good pull. At 120k miles and possibly original plugs, those wires are firmly affixed to the plugs.
After about 60 minutes of effort I managed to get the front 3 off the left bank but that back cylinder is a *****. So far all effort has been fruitless so I’ll have a fresh go at it tomorrow and hope I can get this job done.
2013 Weistec 540/715 tuned CLS 550, 2008 E350, and '07 Jaguar S-Type R
Originally Posted by Shotime
I couldn’t find a set of long reach hose grip pliers but really don’t see how those could fit anyway so after trying 90 degree long reach pliers to no avail, I went with the zip tie method. Looping long zip ties behind the plastic tab on the spark plug wires really gets a good grip on them and allows for a pretty good pull. At 120k miles and possibly original plugs, those wires are firmly affixed to the plugs.
After about 60 minutes of effort I managed to get the front 3 off the left bank but that back cylinder is a *****. So far all effort has been fruitless so I’ll have a fresh go at it tomorrow and hope I can get this job done.
Pretty sure you just convinced me to have my mechanic handle this job - thank you
Pretty sure you just convinced me to have my mechanic handle this job - thank you
Glad I could help you come to a reasonable decision! I’m still wrestling with the last 3 plug wires so in hindsight, the couple hundred I saved by doing myself just ain’t worth it!
I use long reach hose grip pliers. They're around 11 inches long. I try and grab the rubber boot as low as I can. Get at any good tool shop or maybe Amazon.
I used the exact same tool for my plug change and they worked perfectly! I found them on amazon for pretty cheap...worth buying and will save you from tearing up your rubber boots.
I may be too late to help you, but perhaps this will assist others who find this thread. I meant to write something up when I did my spark plug change in 2019. My 2012 CLS550 had 152,000 miles when I got it. As it turned out, it still had the original plugs in there. The grease they used on the spark plug boots dries out over time and becomes like glue, making removal of the boots very difficult! There was a TSB on this I believe. They changed the grease around 2015.
The key to getting the boots off is HEAT! I figured this out because the 1st boot came off easily, since the engine was slightly warm at the time. They got more difficult from there, until I started breaking boots trying to remove them. At that point, the car was not driveable, so I used a heat gun to warm up the boot, and it made a huge difference! It just popped off!
My suggestion - warm up the engine first. Once cool enough to work on, pull all the boots first, before changing any plugs. This would apply to all models with M276 and M278 engines. I ended up replacing all 8 boots on mine, since I broke half and the rest were kind of brittle after all those miles.
Thanks for the info. I followed all the tips except for the warm engine, as mine had been sitting for a
couple of days prior to undertaking this. I did borrow a tool from local indy that helped tremendously with the boot removals because as you mentioned, they are virtually glued on. Unfortunately tools don’t fit well on the back cylinders so I finally got one off with zip ties. Dont think I’ve broken a wire yet but I am stymied by the rear pass side coil bolt that has no room to work on. I can get the socket on the bolt but even a flexible extension won’t fit. Thinking about floor jacking the motor up an inch to see if that helps.
Regardless of the eventual outcome, this job is a real pain in the axx!
Does anyone know how much dealers charge for spark plug change?
I think it is about $400. Plugs and the swivel socket cost me $93 so I am saving a few hundred bucks but in hindsight I'm not sure it was worth it since it has been such a difficult job.
On a good note after much effort, I did finally get the last coil and spark plug wire off so am ready to finish the job. I pulled one plug out just to have a look. At 120k miles and likely original plugs, I expected it to look worse but still see that they need to be replaced so I'm glad that I'll have a new set in.
Yes it was a difficult job and one I wouldn’t want to repeat but after spending an inordinate amount removing the coils and wires, the actual removal/replacement of the plugs was very smooth and took less than an hour.
For those contemplating, call your mechanic! If you do undertake this task, use the swivel socket and make sure to wrap a wire around it so you can retrieve it after torquing the plug
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