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Spark Plugs “92 500E
- Thread starter Eagle01
- Start date
Noooo! Those are fine-wire electrode, resistor-type plugs. DO NOT use those!!
Don't change by time, change by miles, or more specifically condition of the center electrode wear. About 25-30kmi is usually the minimum lifespan where you may see just enough wear to justify replacement. At around 50kmi there's usually significant wear, you probably don't want to go beyond 50k. Interestingly, even with worn plugs, the engine can still run almost flawlessly (assuming the rest of the ignition system is up to snuff).
These distributor-ignited engines need non-resistor spark plugs, which are becoming harder to find, and a LOT of aftermarket vendor catalogs wrongly supercede them to resistor plugs with exotic fine-wire center electrodes (platinum, iridium, yttrium, etc). For reasons I don't fully understand, these engines often run worse with fine-wire center electrodes.
Anyway: You want Bosch F8DC4 (not FR8DC, the "R" indicates "resistor) or equivalent. I believe current F8DC4 are made in Russia. Can't go wrong with the OE/Genuine plugs nocfn shows above, which are Beru 14F-8DU4, made in France. Set the gap to 1.0mm when installing and forget them for another 25kmi+.
I agree with you alot and this, is, also the case for M102/103/104/116/117 etc. Stay with the Bosch. But one point is, getting so bad I have to highly disagree with point of using Beru spark plugs even though they don't have the resistor. That brand has the most notorious bad cheap design you can imagine. Several other types of parts are mentioned and by eksperince here in Europe at least that Beru makes some of the poorest crap and here these won't last 10.000 then your into trouble. Had a set were the ceramic would fall down on to the tip covering up the center electrode. Misfires.
They are, so bad I even prefer Bosch resistor plugs. They do work better and has alot more quality to them than Beru. At least that's, a very common isue with Beru here..
I have, several of my customers bringing in SL S E classes with all sorts of 4 electrode or yrithium sparkplugs. Man they run bad on those. R6 V8 V12 i put bosch in them originals and when they went resistor types. I bought the Beru. And that was a quick no go due to short living errors and cheap quality. So I'm back to the Bosch with resistor. That's not correct, but it works and has less isues than Beru non resistors.
