Oil-fouled Spark Plug?

[Qwerty]

Hi Guys,

I just have a doubt to be cleared before going for an engine repair.

I inspected the spark plugs and 2 of them seem to be porblematic. Their threads were bit oily and the bottom parts (spark place) were dry. Further the bottom part was blacky. The center electrode's white cover was also half blackish. Whats the cause of this actually? I saw some pictures of the oil-fouled plugs and their bottom was wet and oily. This makes confusion.

[Duncan]

Hi

Oil only around the thread area is not much of a concern. What you should look for is oil on the electrode. Oil on the electrode means that you could have a broken oil ring. However, oil can also get into the combustion chamber through faulty valve seals. So identify the problem first.

There is a simple way to check this.....start the engine, bring it to operating temperature and then watch the exhaust. If a constant steady stream of blue smoke comes out, then you have a broken oil ring. If there is no constant stream of blue smoke, but only does so when reving after a short period idle, then it's most likely the valve seals.

On the other hand, black soot on the elctrode is caused by unbernt fuel in the chamber. However, thick traffic running can also cause this.

If the problem is not oil, then do a engine tune up and then do a outstation run at a constant speed. This should clean out the system. Then check the plugs.

Cheers

[Elvis_Pil]

Pictures please

[Duncan]

pictures?

[Elvis_Pil]

Of Qwerty's spark plug that is sorry.