Maybe I am just tired and missing something but I am having trouble getting my 13bt bj74 to take coolant. I drained both the rad and engine petcocks. But now I cant get it fill with coolant without overflowing. I have jacked the front end up and tried pumping on the hoses to get air our of the line. But so far Ive only got about 3.5 liters in. Any Suggestions?