OEM 2005 Mercury Monterey Spark Plug

2005 Mercury Monterey Spark Plug Parts Q&A

• Q: How to inspect a spark plug for a bridged gap and signs of fouling on 2005 Mercury Monterey?

  A: A bridged gap inspection should be performed on the spark plug alongside the examination of deposit build-up between electrodes which can result from oil or carbon faults. Clean the spark plug in case of necessity. Examine the insulator shell bore electrodes for black wet oil deposits as a sign of fouling which indicates ring or piston wear and improper bearing looseness along with excessive valve-to-guide clearance all require repair before installing a new plate. A spark plug needs cleaning if black dry fluffy carbon deposits appear on insulator tips, exposed shell surfaces, and electrodes because they typically develop from incorrect heat ranges, uncleaned air filters, fuel mixtures becoming too rich or from excessive engine idling. Normal burning appears as lightly colored gray or tan residues on the spark plug firing tip. The presence of melted electrodes along with damaged insulator and metallic deposits points to engine damage possibly caused by incorrect ignition timing lapses or delivering wrong fuel types or non-professional heli-coil insert installation into spark plug threads so a new spark plug becomes necessary. Whiteness or light gray coloration with bluish-burnt electrodes exists due to engine overheating or incorrect fuel usage and loose spark plugs or improper heat-ranging spark plugs or insufficient fuel pressure or wrong ignition timing that demands replacing the spark plug. The spark plug should be cleaned if there are fused deposits which look like bubbles or blisters found during the inspection.