prodigymb

you are not the first to use shorter plugs - people have done it before. i haven't raed about any issues arising from that......but that doesn't mean that there are none. i wouldn't run the short plugs in my car.

here is an actual short article from ngk... where they give both part numbers and say that plugs are available outside of mercedes dealers.
http://fr.ngk.de/NEW_AFTERMARKET_NGK...UG.2985.0.html

"NGK’s ILFR6A iridium spark plug is now available for fitment to 19 Mercedes models introduced between 2000 and January 2005 ranging from C160 1.8 litre Kompressor to the 5.4 litre SLR McLaren. The actual Mercedes Part Number is A0041591303"

sneakyneon

I just got off the phone with MB, they say the longer one is correct, talked to NGK tech said that they(ngk) have the wrong plug listed and to use the longer one. I started another thread looking to see if anyone has a head off, I just cant imagine an engine running with a plug that far in the hole. The whole issue of this thread was due to massive carbon built up on the treads. leads me to belive theres more to this.

GRAFH

You have to first consider the website the 2 posted above are distributors not manufacturers website. You were not on ngk's website.

Here is ngk's recommendation > http://www.ngksparkplugs.com/part_fi...gineid=1465954

Their are also 2 different iridiums available from ngk > http://www.ngksparkplugs.com/product...x.asp?mode=nml

The laser iridiums are the oe plugs per ngk. The iridium ix is not even available for the e55.

The ILFR6A is the part # designated for merc by ngk since they are private labeled with the Merc logo on them. Also that link is for ngk europe.

WL55

Grafh, your link shows IFR5D10 and Prodigy shows ILFR6A. Is there a consensus?

prodigymb

NGK ILFR6A is the longer / correct part #. same as sold at MB dealers.

I also just talked to a friend of mine who is a tech that works on my car and he told me he often sees Bosch plugs being used as well. I do not know the part number for the long Bosch plugs though....

no they are not all labeled with a mercedes logo. only the ones sold at mercedes dealership in mercedes boxes are labeled with the logo. ones sold at advance auto parts do not come labeled witha mercedes logo

GRAFH

Here are the part #'s broken down.

I = Iridium/ platinum. Iridium center electrode w/ Platinum pad ground electrode.
L= Short type.
F= 14mm o.d., 19mm/ 3/4" reach.
R= Resistor type.
6 = Heat range. 2= Hot 12= Cold.
A = Special Design/ Firing End Construction

-------------------------------------

I = Iridium/ platinum. Iridium center electrode w/ Platinum pad ground electrode.
F= 14mm o.d., 19mm/ 3/4" reach.
R = Resistor type.
5 = Heat range. 2= Hot 12= Cold.
D = Special Design/ Firing End Construction
10 = Gap of 1mm, .040"

As you can see the lfr's are the short ones & 1 heat range colder.

GRAFH

According to my info the ilfr6a is for the v12 in the cl65 amg & sl65 amg. As well as the 4 banger in the c230.

komp55

Prodigy is correct.