Beru Plug Replacement 4 Defunct Bosch H9DCO - My Story - Page 3 - PeachParts Mercedes-Benz Forum

JamesDean · #1 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 · #2 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

Cal Learner · #3 02-12-2009, 07:58 AM

Quote:

Originally Posted by babymog

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

Yeah, buddy! Welcome to the never ending saga of "what plug goes where."

babymog · #4 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.

cliffmac · #5 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....

cliffmac · #6 02-11-2009, 09:40 PM

the whole deal is the little cap on spark plugs that come attached and you have either leave on or remove, depending on your car. On BMWs the little cap has to be removed to fit the wires, on MB you have to leave them on...different horses for different courses...the bottom line is static in the sound system. Now there is the matter of heat rise and disappation on the electrode, my 633CSi required Silbers (as they say in Germany) $10 a pop. Faster heat rise and dispersion than normal plugs, car wouldn't run properly without them...truth...but that was pretty much the last series that those were required.....I say again, just install what the manual says to, and if that particular part has been superceeded go with that. I would not get fancy with upgrades/alternative versions, doubt it'll work

JamesDean · #7 02-11-2009, 10:03 PM

Quote:

Originally Posted by babymog

...the BKR5E / BKR5ES plug

I decoded that to be: 14mm thread,5/8 projected tip, resistor,19mm (3/4" reach)

Non-Resistor version, This should do:
NGK-7405

pawoSD · #8 02-11-2009, 11:37 PM

Quote:

Originally Posted by JamesDean

I decoded that to be: 14mm thread,5/8 projected tip, resistor,19mm (3/4" reach)

Non-Resistor version, This should do:
NGK-7405

Those have the wrong seat style. Can't use them.

babymog · #9 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.

pawoSD · #10 02-11-2009, 10:18 PM

Quote:

Originally Posted by babymog

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

LOL.

Holland is the only place I've been where the roads make 0 sense at all. I did a tech project at the schools there.....what a confusing city.

Our 300E is running resistor champions right now, and runs just fine...they've been in it a long time though, so I just ordered some NGK's (probably resistor) and will throw those in when they get here and see what happens....

Tonight I found that the serpentine belt has snapped a cord and is dying....so I need to order a belt!

Annoyingly enough, I just placed an order yesterday for some stuff (lock tumbler) and such....I wish I had known about the belt then!

babymog · #11 02-11-2009, 10:31 PM

Summit lists the 7405 as a "manufacturer heat range: 9" and the BKR5E as "...range: 5". The BKR7E is closer to the 7405, possibly the 7942 but there's no direct reference to the heat range. I'll check on the NGK site to see, hopefully you've found the plug series.

Still, as much concern as there seems to be about running the resistor plugs, I've found the resistor copper NGK to work quite well.

babymog · #12 02-11-2009, 10:35 PM

There's one at LKQ, I left it there when I scrounged the tensioner LOL.

Don't expect changing the belt on that gasser to be as simple as the diesels, I am beginning to think that the Engineers at Mercedes-Benz were trying to punish people for making them design cars with gasoline engines by making the maintenance so rediculous (in comparison to similar tasks on the diesels).

I think I have found a way to curb my Mercedes buying habit: buy a couple of gassers, cured!

pawoSD · #13 02-11-2009, 11:39 PM

Quote:

Originally Posted by babymog

There's one at LKQ, I left it there when I scrounged the tensioner LOL.

Don't expect changing the belt on that gasser to be as simple as the diesels, I am beginning to think that the Engineers at Mercedes-Benz were trying to punish people for making them design cars with gasoline engines by making the maintenance so rediculous (in comparison to similar tasks on the diesels).

I think I have found a way to curb my Mercedes buying habit: buy a couple of gassers, cured!

Was the belt in very good shape? I can't remember how new it was/the condition. If it was I'll go pick it up!

Maybe the M103 is easier than the M104.....in the FSM it just says to remove the fan, and then remove/reinstall belt. No touching the tensioner or anything! Sounds simpler than the v-belts on a 617......