A few days ago on the newsgroup alt.auto.mercedes, a question was posed about the Bosch platinum plugs. The original poster stated that he had heard of the platinum plugs coming apart, leaving chunks of metal or porcelean in the cylinders. He went on to say that platinums should not be used in 117.XXX engines, his being a 117.985.

I have used Bosch patinums for about 10 years now, first in an old Ford, and latest in my 73 280 SEL (117.984). As soon as I bought the car, over a year ago, I put a set of platinums in. Runs fine, no broken plugs, no chunks of metal etc.

Has anyone here heard of the problem the original poster referred to? If there truely is a problem with platinums in 117.XXX engines, I'll change them out ASAP. If not I'd just as soon keep using them.

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Mike Tangas
73 280 SEL

Any spark plug can come apart due to excessive spark knock. Platinum plugs are designed for much newer engines, the size of the electrode is very small & can foul very easy. Copper core plugs will perform much better on cars with 2 valve cylinder heads.

[This message has been edited by M.B.DOC (edited 04-05-2000).]

A MBZ dealer friend told me of a customer who ruined an M103 motor with Bosch Platinums. And because they were not approved plugs MBZ would not warranty the motor (car was a year or so old at the time).

I trust this guy, so I'll be staying clear of the platinums myownself!

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Best regards, Michael
'92 500E
'88 300TE

Thanks for the input. Looks like I'll be changing out plugs here pretty quick.

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Mike Tangas
73 280 SEL

Lots of Independent shops use platinum plugs, they are often used for an engine that is starting to burn oil because they burn a little hotter. I have never heard of a problem with Bosch platinum plugs and do not remember ever seeing any technical info from Mercedes-Benz to the contrary (20+ years at dealers).

A properly running Mercedes will run just fine with the normal Bosch plugs.

How about a discussion about Spark plug replacement intervals?? Some change them at 15,000 miles or at 30,000 or more. Assuming we are talking only about fuel injection, would the different fuel injection systems (CIS, CIS-E, LH, HFM, or ME2?) require less frequent changes??

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What happens to the porcelin in the cylinders and will it damage the engine? I will put Bosch copper back in, does anyone else suggest a better plug?

Stiefel,

Are you saying that there is porcelain inside a cylinder?



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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

I went to purchase spark plugs for my 1990 190e 2.6 at a reputable foreign auto parts store, that happens to be an authorized Bosch parts distributor. They told me not to run platinum plugs in my Benz. They said the platinums rum fine in other cars but not German cars due to the high voltage ignition output. They told me to run the regular Bosch plug due to complaints of misfiring and such.

I never found out what happened internally on that engine. About the time that I had read that message I stopped looking at the newsgroup and stayed right here. But I imagine that a chunk of porcelin rattling around in the chamber could do some damage if big enough. Porcelin, is pretty dense stuff, in fact the porcelin part of a plug will break a car window.

Shortly after asking my question, I pulled my plats and went to Bosch copper core, AutoZone had a sale on them for something like 59 cents a pop. I had a slight miss at idle, and with changing to copper cores the miss was eliminated.

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Mike Tangas
73 280 SEL 4.5