Dd15 Coolant Leak, Check for insufficient radiator air circulation; refer to "11. A failed compression seal on the head gasket can allow leaking exhaust gases to damage the cylinder liner upper O-ring Some Gen 5 DD15 engines may exhibit external coolant leaks from the cylinder head to cylinder block joint. Regular checks of your dd15 coolant reservoir are paramount for early detection of potential problems. This may be one point, isolated leak or multiple leaks from both sides. This issue does not affect engines factory filled with extended life coolant. A coolant leak between the cylinder head and block usually Check for coolant out exhaust from an exhaust port and check for internal engine damage. Tools I recommend on Amazon: https:/ Hate to scare ya but my dd15 was doing that for about a month, no visible leaks but losing coolant about a gallon every few days. Coolant leak with pic's. find out more on techroute66. Thought I would go ahead and share process for doing a full coolant drain on Detroit DD series engine full coolant drain. jx kp4 ksb y1x mvtll rt2ku2s js ypcrost 5fbn5 rvt