Beru Plug Replacement 4 Defunct Bosch H9DCO - My Story - Page 5 - PeachParts Mercedes-Benz Forum

Cal Learner · #61 02-11-2009, 09:12 AM

Just went through the aggravation of finding the correct non-resistor plugs for the M103 motor. Finally ended up with 12 new NGK BP5EFS plugs from a UK online merchant (what a mess, but it all eventually worked out). But here's the good news: Tom Hanson at the MB Classic Center in Irvine says they stock these NGKs, so that ought to be a reliable source for anyone looking for copper core, non-resistor plugs. And with your MBCA discount, they're 15% off MSRP. Of course, you'll miss out on all the aggravation of doing it the way I did, but maybe you can live with that??

Hit Man X · #62 02-11-2009, 05:04 PM

BP5EFS seem to be resistor, when I ordered some I received TR5s.

Car runs on them, FWIW

babymog · #63 02-11-2009, 06:10 PM

I've not been able to find non-resistor plugs for the M104, bought NGK BKR5E (resistor) instead and have had no trouble.

I've also never gotten an answer here what the non-resistor plug for the M104 is, nor have any others who I've found who posted the question here, so I'm not sure that they exist.

JamesDean · #64 02-11-2009, 07:31 PM

NGK Racing R5724-9 Plugs:

They seem to run well in the car. A lot better than the Bosch +4 platinums.
I didnt get to snap a pic, they look like just as you would expect a plug to look. They DO NOT look like the pic on the JEGS website.

Sources for these plugs:

http://www.jegs.com/i/NGK+Spark+Plugs/739/R5724-9/10002/-1
http://speed-eng.com/store/ngk-spark-plugs-m-77.html
http://www.scpraceparts.com/circle_track_racing_parts/ngk-708-full-thread-5-8-hex-projected-tip-spark-plug-1.html

They are fairly cheap @ ~$2.70/each

Pic:

babymog · #65 02-11-2009, 08:44 PM

Are these for the M103 or M104 JD?

JamesDean · #66 02-11-2009, 08:46 PM

Quote:

Originally Posted by babymog

Are these for the M103 or M104 JD?

These have been tested in the M103..not sure about the M104. If it takes H9DC0 then these will work...

babymog · #67 02-11-2009, 08:50 PM

The M104 takes a different size plug, but the NGK heat range 5 is correct, I thought that the M103 took a NGK heat range 4 (hotter) plug for stock performance, perhaps this is colder for higher-rpm / racing?

Hit Man X · #68 02-11-2009, 08:51 PM

Bosch/NGK fade together for heat ranges, they're weird.

cliffmac · #69 02-11-2009, 08:56 PM

the resistor plug is simply to keep clicking out of your stereo...that's all...has nothing to do with the actual firing of the plug....just put whatever the damn car calls for....

babymog · #70 02-11-2009, 09:02 PM

Tell it to the waste-spark gurus here, welcome to the middle of the movie.

JamesDean · #71 02-11-2009, 09:09 PM

why does it not have anything to do with the firing of the plug?
arent you adding resistance to the power being sent in?

cliffmac · #72 02-11-2009, 09:15 PM

Holland Michigan, interesting place. what was it GE Westinghouse or whatever that shut down over there. I go to Grand Haven every fall for an
annual golf outing, killer courses around there. I especially dig Brigadoon, Grand Haven CC and Lake Michigan Hills. But I digress, why would anyone put a resistor on a spark plug when the idea is to throw as much power to the plug to fire the cylinder as possible? Why? Think about that for a minute

babymog · #73 02-11-2009, 09:22 PM

The story here is that the cars (M103 & M104) were designed with resistor wires, and non-resistor plugs. Since that time, Bosch et al have phased out the non-resistor plugs and only the resistor versions are available, which are not optimum with the resistor wires (actually ends) that are in these cars.

So, non-resistor plugs seem to be the holy-grail of plugs for these cars, and non-platinum (especially for the waste-spark system of the M104 and others). Problem is finding them. Many have told me that I need non-resistor plugs for the M104, but nobody is able to supply a part number, and NGK's website doesn't list a non-resistor version of the BKR5E / BKR5ES plug, ... neither does Bosch, so I'm guessing that there is no such animal.

So, I put the resistor NGK plugs in one of my M104s, have used it for city/mixed driving, and after approximately 5,000miles so far it runs and idles perfectly. Rather find the "correct" plugs, but will buy what I can find.

babymog · #74 02-11-2009, 09:23 PM

Yeah there was a GE plant, it's now a Menards. They haven't shut down Lake Michigan though, so not much has changed.

cliffmac · #75 02-11-2009, 09:27 PM

why would you introduce resistance into a circuit where the whole idea is to provide as much non-resistance as possible? come on here....you have to think about the principle of operation....