1996 Jeep Cherokee COOLANT MIXING IN OIL

STOPED ENGINE FOR 1HOUR GOT BACK IN SWITCHED IGNITION KEY ON -MESSAGE LOW COOLANT-FILLED COOLANT DROVE 2KM SAME MESSAGE-TOOK TO MECHANIC -TOLD IT WAS HEAD GASKET-HEADS OFF-HEADS DONE NEW GASKETS-SAME PROBLEM-BACK TO MECH-TOLD IT MUST BE CRACKED BLOCK-ENGINE OUT PRESSURE TESTED-NO CRACKS-NEW RINGS -PISTONS GLAZED-BLOCK RE-SLEEVED ALL 8 CILINDERS NEW BIG AND SMALL ENDS-SAME PROBLEM-BACK TO MECH-TOLD IT MUST BE INTAKE MANIFOLD CRACKED-MANIFOLD OUT PRESSURE AND UV TESTED NO FAULT-RE-ASEMBLED NEW GASKET SET AS PER MANUAL-3MONTHS DOWN THE LINE-ALMOST NEW MOTOR-GUESS WHAT SAME PROBLEM-I WILL DRIVE THE CAR FOR TEST DRIVE 100KM NO PROBLEMS COOLANT FULL OIL FULL GET BACK STOP THE CAR CHECK BOTH ALL OK, 20 MINUTES LATER THERE IS NO COOLANT IN RESERVOIR AND OIL DIPSTICK IS MILKY (OIL AND WATER) PLEASE ANY CLUES