I'm replacing the coolant on a D5B. There appears to be no information in the service or maintenance manuals about where the coolant should be drained from. There is an obvious drain at the bottom of the radiator, but after using this, I'm still about 2 gallons short. If I pour clean water into the radiator, it comes out looking like mud. I expect the other two gallons of coolant are sitting in the block, but there's no obvious drain that I can find. There is also no indication on just how high in the radiator the coolant level should be. I assume there is no overflow tank like a car and the system is designed to have air/vapor in the top of the radiator rather than be 100% full? Any help on this would be appreciated.
left side of engine block between oil filter and cooler is a drain plug takes a 3/4 inc socket it is a short headed plug so use a good 6 point socket may also be one on bottom of trans cooler that looks the same.
Mine is a D5C (1997) The plug is on the left side of the block near the rear just above the oil pressure sending unit. I believe it takes a 9/16 socket. Here is a picture with it out.