M116-M117 Spark Plug Questions? - PeachParts Mercedes-Benz Forum

GradyService · #1 01-02-2007, 09:13 PM

In my M117 560, I installed a set of Bosch Platinum 2's about 6,000 miles ago. It seems to do fine, but looking at other threads, some are saying that non-resistor plugs are the way to go. I believe that the platinums I installed are resistor, and do you think that the next time around the Bosch Platinum 4's are worth the money?
Thanks, and God Bless,
Dave.

troylatif · #2 05-03-2008, 03:49 AM

I've run into the same issue for my 380se. By chance I looked up denso for the m116 (should be the same as your m117), and they suggest a w20epu. the question I have is, does anyone know if this plug has a resistor in it? I'm guessing if it says "r" or "R" in the title then there's the possibility that there's a built-in resistor.

What about NGK's or Beru? I've seen a post regarding the popular NGK plug threads not fitting or something about the geometry not fitting in m103, m104 engines. Does this extend to the m116 and m117 engines?

Can someone second all this?

troylatif · #3 05-03-2008, 04:40 AM

Okay. I think I've found something. I found this nifty cross-reference tool on the Denso website.

http://www.denso.com.au/sparkplug/xref

They list Bosch as an option. Selecting W9DCO, you get the DENSO W14EP-U plug as a possible replacement according to DENSO.

Go to the Champion website (not like I'd actually use these in my car). Search their site and you get their N11YC plug as a replacement.

Go back to the Denso website cross reference page and look for the Champion N11YC plug. It doesn't give you the Denso W14EP-U plug. I think it gives the W16EP-U. Does anyone know the difference between the denso w14 and w16 plugs?

At any rate, go to NGK website. Look it up by car, and I find that the m116/m117 recommendation is the NGK BPR5ES (listing number 7734). This plug has a resistor. They make a nonresistor equivalent which goes by BP5ES. Its not the BP6ES or BP7ES as some of the posts suggest on this site. Is their recommendation wrong? is the 6 or 7 series plugs better for some reason that the manufacturer's not aware of?

Again, go back to the Denso cross reference and the NGK 5 series plug matches to a W16EP-U Denso plug. Is this definitely the non-resistor plug to get?

I also searched Autolite and I found that their website recommends their number 64 plug which is definitely a resistor plug. However, if you go to the cross-reference Denso page, you'll find that the Autolite 54 is the Denso W20 equivalent and the Autolite 55 is the W16 equivalent.

Pheeew! Now that that's been said, I haven't gone to the store to see what's available and I have no experience with the general qualities of all these brands. Can someone put their $0.02 so as to what's the best bang for the buck with regard to brands?

jhodg5ck · #4 05-03-2008, 01:41 PM

I been using NGK BP6EFS and BP5EFS (For cars w/ tired heads) for some time now w/ Great results, in conjunction w/ a .028 gap on the 5's.

I did have some Beru's for a while, but since Borg Warner bough Beru getting ahold of their products has become more difficult and the last set of wires I received had to be re-built before I could use them (ends not crimped properly).

I've been using Denso plugs in my AMG 32V engines as Bosch doesn't make the correct plug anymore...so far no complaints!

BP5's are likely OK for a 380/420 but for a 500/560 I'd go w/ the 6....unless your heads are Tired and your burning a good bit of oil, then I'd run a 5.

Anything w/ an R in it is a NO. A resistor plug combined w/ resistor leads and stock cap/rotor will exceed Mercedes maximum recommended levels of resistance, to which they say damage to ignition componentry could (and IME does) result.

I'd say everyone is referencing what Bosch recommends these days, ie everything w/ a resistor built in..

Jonathan