Carbon build-up on spark plug

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Author Message   Damien Vrontisis (Dvrontisis) New Member Username: Dvrontisis Post Number: 12 Registered: 04-2003 Posted on Tuesday, April 22, 2003 - 12:09 am:    About 2 weeks ago, I cleaned and regapped my spark plugs. One particular spark plug was exceptionally dirty with (what i assume is) carbon build up. Why is this? Could this be related to my engine knock?   Damien Vrontisis (Dvrontisis) New Member Username: Dvrontisis Post Number: 16 Registered: 04-2003 Posted on Tuesday, April 22, 2003 - 12:28 pm:    Any Help would be appreaciated.   Ron L (Ronl) New Member Username: Ronl Post Number: 26 Registered: 11-2002 Posted on Tuesday, April 22, 2003 - 03:15 pm:    You may have a valve seal or valve guide starting to fail, which may leak oil onto the plug and burn it to a crisp with the end result as a carbon (look) like buildup on the plug. If this is the problem, it will get worse over time and cause smoke on start up. It will also eventually soak the plug to the point where ignition is near impossible resulting in a miss-fire.   Damien Vrontisis (Dvrontisis) New Member Username: Dvrontisis Post Number: 17 Registered: 04-2003 Posted on Tuesday, April 22, 2003 - 06:25 pm:    how can i repare this if it is the case?   Damien Vrontisis (Dvrontisis) New Member Username: Dvrontisis Post Number: 23 Registered: 04-2003 Posted on Wednesday, April 23, 2003 - 11:48 am:    any ideas?   Ron L (Ronl) New Member Username: Ronl Post Number: 27 Registered: 11-2002 Posted on Wednesday, April 23, 2003 - 12:51 pm:    I would pull that plug again after about 1000 miles and compare it to another. If its significantly darker, than what I mentioned may be the problem. If its slightly darker, its possible that this particular cylinder does not breath as much as the others, resulting in a rich mixture which will cause a significant amount of waste/carbon after the combustion chamber goes through its cycle. pending the results, I would not really worry about it until then. If its significantly darker, you could pull the valve cover and inspect the seals, but this is hard to do without the right tools, particularly a valve spring compressor and an air compressor with a fitting for the sparkplug hole.