Has anyone had a problem with the Bosch spark plug insulators breaking . I have a 87 2.3-16 this weekend while driving to the coast I had a failure of a HR8DPX plug part of the center electrode broke . The end result is no compression in cyl no 2 .About 12,000 miles ago I had a similar failure where only a small part broke off. This happened on the same road same place it is an up hill passing lane running at nearly full throttle and part way up the hill the plug failed . Has anyone had similar failures ?

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THIS is a result of excessive combustion temperature and(or) spark knock. POOR quality fuel or very low octane.
ALSO platinum plugs DON'T work well in older cars!!!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Is that plug a platinum? If so, do a search on platinum plugs. Your picture shows very well, what some of us have tried to describe with words. As Doc said, plats do not work well in the older cars...stick with copper core plugs.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

I've had platinum plug in my '89 2.6 for at least 60k miles with no problems whatsoever.

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

I used the Bosch platinum once in my 1990 300E for about 15 kmi with no problem either.

But I replaced them with regular plugs based on what I heard.

I still have these plugs in my trunk as spare.

Bo

Just a little more information I always use Chevron premium fuel . I also have good hearing and have never heard any spark knock with this car . Unfortunately this type of plug was in the car when I bought it ( the previous owner said always maintained by dealer ) .

Well I got the head off tonight and the results are 1 exhaust valve has a chunk out of it . The piece of spark plug got under the valve and cut a notch in the valve then the blow torch effect set in . No damage to the seat or piston or cylinder head . I wish I would have found this site sooner . Now to get the Bosch plugs out of the Alfa . Do you service technicians recommend replacing all of the head bolts , the manual says to just check for stretch 120,000 miles on the car .

Just measure the total length of each bolt(not including head or washer). I have found that they can go thru 3-4 head gaskets as long as the engine hasn't overheated.
Length new is 110mm & max length is 113mm

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator