I have a 1992 Merc. 150 that runs well. I took the spark plugs out and noticed what looked like fine rust on the ends of the spark plugs. It had been about 2 weeks since last running it. Only the spark plugs on the port side showed this unusual coloring. Is water getting into these cylinders? Could the head gasket be bad, and if yes, any special precautions when changing it? Any help would be appreciated. Thanks,Joe
