|
Gray-Brown
deposits, lightly
coated core
nose. |
|
Normal |
||
|
Electrodes
apperas glazed, core nose is very white. Eventually wrong heat range of the spark plug (to hot) Hint that the fuel mix is to lean! Check ignition timing. Maybe gasoline with to low octane-rate. |
|
Overheating |
||
|
Sooty, dry and black deposits Hint on to rich fuelmixture. Check also ignition-timing. Maybe spark-plug with wrong heat range in use (to cold). |
|
Carbon Fouling |
||
Wet and oily deposits, wet and oily electrodes The reason could be worn out pistonrings and/or bores. Also worn out valve guides and valve stem seals could be the reason. In rare cases plugs could look like this due engine break in. |
||
Öil Fouling |
||
|
Crusty, light-grey sandy deposits build up through gasoline- and oil-additives. Also a hint on defect valve guides, valve stem seals and pistonrings. Also cuased by idling for long periodes. |
|
Heavy Deposits |
||
|
The plug insulator firing tip apperas yellow or green/yellow and shiy. Caused by wrong carburation, excessive idling followed by hard acceleration. Also check ignition-timing! |
|
Lead Glazing |
||
|
Burned away electrodes. Core nose has burned glazed appearance. Hint on pre-ignition. Check ignition-timing! |
|
Electrode Damage |
||