I'm currently in the process of flushing the coolant in my 1987 300D. I drained the radiator and block, added the flush solution, and then attempted to fill the system to capacity (10 quarts). I only managed to get 5-6 quarts in, and now the level in the coolant tank doesn't want to go down any lower. What gives? Squeezing the upper radiator hose doesn't seem to do much. I recall someone mentioning that it takes some time for the coolant to "sink in" to the system, and it's possible to get in almost 9 quarts before starting the engine. How long should this take? A few hours? Thanks in advance!