Does anyone know why my 5.4L 2000 Expedition has a tube that comes up like a hose would fit on that has a cap? This thing has from time to time leaked and I cannot figure out how to fix it permanently. When it leaks coolant spills into the spark plug wells (#1 & #2 to a lesser extent) and winds up fouling my coil pack and or spark plugs.

This tube is located toward the center of the engine in front of the intake, above the alternator and adjacent to the #1 cylinder. I believe it is attached to the crossover tube.

Is there supposed to be a hose connected there? We have owned this vehicle for 10 years and to my knowledge there was never a hose, but always some kind of cap (like a vacuum plug) held on with a clamp. Occasionally the rubber wears out and it leaks so I have to replace the little cap.

Any ideas for a more permanent solution?

 

A pic would help, a lot.

 

Since you're in Texas and probably never use the heat, it sounds like a previous owner disconnected the heater hoses and capped off where they connect. The other one would be the around the rear corner of the engine on the passenger side.

If I'm correct, your solution (short of repairing the heater system) is to find a more heavy duty cap.