Leaves and dirt get in the vent and collect in the drain tube. It is located passenger side of the firewall near the center. The shape of the hose doesn't let it always drain solid materials that collect inside. Then it rains and the water can't drain. Look for the hose you will see what I mean.
You don't need anything else. Clean the hose out regularly you will be fine.
89 2.5 TBI, 4" RC lift, 1" Booms, SYE, Adams Driveshafts front and rear, Ford 8.8 with 4:88s, BFG 33X12.50X15, and a ton of other stuff.
AF Jeep Club Tail Number 184