Looks like it is where you heater hoses are connected to the heater select valve. May be an old hose that is cracked under the clamp.
It is probably time for new hoses and a radiator flush.
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