I have a 1999 grand marquis and was changing out my spark plugs and found ain't freeze on em and on the ground don't where the leak is . How can I find the leak

Was the antifreeze on the outside of the plug or on the electrode part? If it was on the outside try running your hand on the areas above the plugs (when engine is cold) and see if you can locate the source. Check hoses and clamps carefully as well. Antifreeze can drip down a hose from the area where the actual leak is.

If the anti-freeze is on the electrode part of the sparkplug and it didn't drip or run down from up above onto the plug, that means that you probably have a blown head gasket and antifreeze from the cooling jacket in the head is passing thru the blown area of the head gasket and getting into the engine block cylinder. Your engine is so hot inside that it will burn off the anti-freeze just like the gasoline in the cylinder thus you won't show a leak on the outside or it might be so small of a leak that you won't see it. Either way if you have anti-freeze where you should have it, then there is a leak somewhere and more than likely from a blown head gasket or a wornout heater hose or even a worn radiator hose depending on where you found the fluid. They do make a dye that you can pour into your radiator or overflow tank and then you hold a small blacklight against your engine and the dye will show up under the blacklight light. The auto parts store should have the dye and the blacklight to go with it, maybe in a kit or separately. Or you could take it to a repairshop or a radiator shop and have them check it for you, but don't drive the car too far if it's leaking anti-freeze as you could do major damage to your engine as it will over heat without the right amount of fluid in the radiator. Good Luck, Kenny/MrBlueOval.