Ford F8CZ-6N664-AA Crankcase Ventilation Tube

Vacuum hoses are often color-coded and require specific characteristics. When checking vacuum hoses, use hoses made of the same material when replacing them. If necessary, remove the vacuum hoses from the vehicle for a thorough inspection, and label them for proper reinstallation. Inspect plastic T-fittings for cracks and check the hose where it fits over each fitting for distortion. You can use a small piece of 1/4-inch inside diameter vacuum hose as a stethoscope to detect vacuum leaks by listening for hissing sounds.

You can use a small piece of vacuum hose as a stethoscope by holding one end to your ear and probing around hoses and fittings, listening for the characteristic "hissing" sound.