2003 ford expedition moisture on spark plugs

” I drive a 2003 ford expedition. We have replaced spark plugs and a mechanic told us somehow we are getting moisture in them. We have cleaned out the converters. The car is misfiring and is getting bad gas milage. Can you help.”

Generally, if you get moisture on your spark plugs, that moisture is antifreeze from your cooling system. This means that either the head gasket on the engine is starting to blow, or the intake manifold gasket is starting to go and coolant is getting sucked into the engine. Unfortunately, you will have to take the engine apart to discover where the problem lies. BUT, here’s a test you can have a mechanic perform. Have them pressure test your cooling system. If the pressure is lost quickly, then the intake manifold leaking could be the problem (assume you don’t see leaks anywhere else when it’s pressurized.) If you don’t lose pressure quickly, then odds are it’s the head gasket that’s starting to blow, as you won’t lose pressure quickly if a head gasket is starting to go. Hopefully it’s the intake, as that’s a MUCH cheaper job than a head gasket. Good Luck,