white plugs

[sean sherry]

Add this to the list of things I don't understand........plugs by Bosch always darkish Grey. Changed them to NGks after a trip to Cootamundra a week ago. Same petrol from Cowra
Then a couple of shortish runs to the Shops , plugs are now white on the electrodes ( black around the body ) Needed a slight tweak to richer and also to the faster idle speed ( about 50 + revs ). The Bosch Plugs were still good but had a few miles on them. ????????.
.............Sean

 

[Helmet]

Add this to the list of things I don't understand........plugs by Bosch always darkish Grey. Changed them to NGks after a trip to Cootamundra a week ago. Same petrol from Cowra
Then a couple of shortish runs to the Shops , plugs are now white on the electrodes ( black around the body ) Needed a slight tweak to richer and also to the faster idle speed ( about 50 + revs ). The Bosch Plugs were still good but had a few miles on them. ????????.
.............Sean

I'd say they turned white after the long run and starting to darken after the short runs, sounds normal to me.

 

[sean sherry]

No ,the other way round Helmet, grey always ( with Bosch ) including after the trip to Cootamundra. But white after the change to NGKs and after two short runs to the Shops. ....I agree it should be dark around the City and whitish on a long hot run. .... Sean

P.S. I'm trying desperately to avoid opening the engine re the valve stem seals. With an 85% thermostat the Temp. from Cootamundra via Cowra was running at 90% driving in the 3 to 5000 range. I have now fitted a 71 % thermostat and sticking to the speed limits ! The Radiator keeps the Temp to the high seventies. Time will tell.......

 

[sean sherry]

Maybe I need a colder plug. I used the NGK equivalent from the chart. An old Post suggested that I should have gone one number colder with NGKs ????

Sean

 

[Ricord]

Of course, you need colder plug, it pretty much is a must for your situation. Good luck

 

[BenzBoy]

The following may be helpful and supports Helmet's analysis - http://www.ngk.de/en/technology-in-detail/spark-plugs/diagnosis/
and - http://www.ngk.de/en/technology-in-detail/spark-plugs/diagnosis/defects/
Regards,
Brian

 

[sean sherry]

Well it seems that the printed Chart for equivalent NGK from Bosch is wrong. The no 5 is to hot and should be a colder no. 6. .. NGK's own web site recommends no 6 for a 280 SL 107. I'll pull a plug again to be sure and fit the correct plugs........Sean

 

[BenzBoy]

I'm sure you already know that the NGK heat range numbers run the opposite to Bosch's.
Regards,
Brian

 

[sean sherry]

Yes Brain , I've doubled checked on the official NGK site that and 6 is colder than 5..
Sean

 

[sean sherry]

The sixes have it ! ! the difference between 5s and 6s is night and day. Now a light grey instead of a stark white.
I guess it is easier to correct a wrong item on a web page compared to a print run of thousands of Charts.........Sean