SNW HAD SAME ISSUE ON TRUCK WITH 15,000 MILES AND 4800 HOURS. WAS POURING COOLANT OUT OF EXAUST,PULLED UN TESTED BOTH COOLERS, NO PROBLEM, COLD LINE HAD ME PULL ALL GLOW PLUGS OUT AND CRANK ENGINE. NO COOLANT EXPELLED.REASSEMBLED ALL AND TRUCK NEVER LEAKED AGAIN. OIL HAD COOLANT IN BOTTOM. BEEN IN SERVICE FOR 10,000 MORE MILES NEVER HAPPEND AGAIN. WELCOME TO THE TWILLIGHT FRIGGEN ZONE.