Diagnosing plug faults

[Tea]

I just found a great book on cars (maintenance, tools, etc) published in 1970 at my grandparents and thought this page may come in useful. Saying that, that every one of the 440 pages are brilliant. You may need to get out a magnifying glass to read the descriptions
Not sure of the copyright laws so I'll not put up the name and understand if taken down.

[frame][/frame]

[bmcecosse]

These aren't 'plug faults' - spark plugs are extremely reliable. They are a well known method of diagnosing some engine faults by reading the plugs....

[MrIan]

Yeah I remember it as it was in nearly all manuals I had for various vehicles. Something for the younguns !! to look at n learn about engine condition.

[SteveClem]

Without being pedantic I do think that Tea's picture is a very useful guide.