Super SEC
Since this was not your car you are just uninformed. I have been working on exotic cars for over 25 years professionally; I have seen preignition before I know what it looks like. Since I am the one that removed the head and did all of the repairs I was able to look at the head and pistons to determine if it was preignition and there were no signs of any. This is also not the last time I have seen platinum plugs fail when using them in a car not designed for them. It is easy to sit behind a keyboard and make diagnosis but I toughly researched this problem when it happened and there are many cases of this happening with platinum plugs. I simply posted this to help anybody else from suffering the consequences of using platinum plugs where not specified.

If you are such a firm believer that the plugs and only the plugs were to blame as to your engine damage, take Bosch to court. The company is liable for a defective product and it sounds like you are pushing all of the blame on Bosch Platinum plugs. Were you running resistor plugs in a system that was designed to have non-resistor plugs? What would cause the ceramic insulation to basically explode other than knock, preignition, or excessive heat?

I was running the Bosch recommended plug for the application. When I contacted Bosch thru several avenues I could not get any response. I felt that it would be a large expenditure of money spent on attorneys to recoup my costs. If I had to take my car into a shop for repairs and spent the money there it might have been a different matter. Since this happened I have just been running NGK plugs and have not had any problems like this with no changes to the fuel or spark settings.

If this problem was as rampant as you are suggesting, I'd bet there would be a lawer that would take a class action suit against Bosch so they would pay for your damage as well as all the other engines that were supposedly damaged from platinum plugs. The damage you have just looks suspiciously like a preignition problem caused by a sparkplug that was too hot for the application. It really doesn't matter if it is platinum or a copper core plug because the same damage would be caused to either plug in that situation. I hope you work it out and this problem does not happen again.

I have worked out the problem I have NGK's in it now and have not had this problem since. If you do a search on the Internet you will see that I am not the only one that has had problems. I do not have all of the data still since I upgraded my computer, I did however find enough to satisfy myself that this is a common problem. Bosch platinum’s in high performance applications where the cars are driven hard have the problem with the insulator fracturing and breaking apart. Most people that have had this problem just develop a miss and find a broken insulator. In my case it nicked an exhaust valve and then the valve burned.

What do you think is causing the ceramic to break apart?

My only thoughts are that the electrode wears funny because of the lower voltage or that the electrode expands because of the lower voltage.

I bought some + 4s for my 400-E . The recommended plug for the M119 being Boush 4418. I remembered seeing some negitive comments on these platinum plugs on this site so before installing the plugs I decided to do some more research. My findings are that there will in most cases be a recommended plug for your vehicle as in my case a 4418 which is (1) is a plug of a higher heat range than should be used in this engine causing the plug itself to be overheated especially x-way driving causing plug failure and engine damage. (2) It is a resistor plug, Mercedes has built the resistance into the plug wire end caps thus using these plugs which add more resistance could cause the electrode to explode leaving the fragments in the cylinder, lodged in a valve etc. (3) There are 4 prongs on these plugs with a preset gap of .070. The recommended gap for the M119 in .040 leaving an excessive gap of .030 on 4 prongs which equals .120 excessive gap if it fires to all 4 resulting in an overworked ignition system and a very weak spark resulting in unburnt fuel.

FWIW, I replaced the plugs in my 1998 C43 shortly after I bought it in late 2003. It still had the original plugs from early 1998 although there were only 30,000 miles on them. Several dealerships recommended the Bosch F8DPP332 plug. This is a platinum plug with one side electrode. I installed them and have had no problems in 4,000 miles.

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Dan
1998 C43

I went to napa the other day to purchase some ignition system tune up (cap, rotor, plugs, wires) and the guy said that the wires cost 260$. I thought that was kind of outragous since the wires for my honda only cost 25 or so. I was wondering if you guys knew of a place that sold a "performance" set of wires or even just regular wires for less than 260$.

My car feels like it's missfiring (it shakes alot in and out of gear) and i read this thread and thought maybe it needed new plugs. But then again it has 260K miles so who knows what could be wrong with it.

Go by your local autoparts store and pick-up a set of universal cut to fit. I've got them on my SEC and they work like a charm. Oh yeah, they were only $29.95 and look cool too! Make sure you get the proper end type. They have straight boots or curved boots. I had to use the straight boots on my SEC. The plug wires are made to work with the little screw down caps on the plugs installed. The OE Mercedes ones that came stock on my car will not work with the caps installed so lucky for me I had some old plugs with the caps and transferred them to the ones on the car.

after putting in the new NKG copper cores, my car drives like it is brand new (or close to). It stoped shaking and finally accelerates again. The plugs i pulled out were awfull looking. They were all "gunked" up with grease, corroded, bits of porcelin missing (probably in my engine somewhere), and were over gapped. The gauge i use only goes up to something like .045 and it was bigger than that! I found that amusing as the gap specifications are .30. Time to find a new mechanic i suppose.

Buy the proper original plugs and you dont have to worry.

The ignition system have been tested with the originals but not with the extrasuper or whatever.
My car died for me when i was far away ,i then used platinums and they had totaly been eaten by the hungry benz.
No platinums in my old benz anymore.

Plugs are cheap

Pelle

300E 4M -89

this topic is never end

I'm currently using Platinum +4 in my 1988 MB 560SL. The car is 100% stock.

I can regularly exceed 17 MPG on the highway. (Factory sticker claims 14/17)

My best 1/4 mile time was 15.075 seconds, (This beats any published ET I'v ever seen for this car)

I currently have 20K miles on these plugs

The car idels rougher than I would expect.

My next set of plugs will be Bosch Copper W9DC's and I will try to get the same data.

Also the MB 560SL owners manual does list in the a Bosch platinum as a replacement plug (Not a Platinum +4). The Plug is a W9DP, which I cannot find anywhere.

John Roncallo