Trouble draining coolant on 2005 Mercury Grand Marquis
The engine holds coolant and so does the heater core, the core not much but the engine holds maybe 2 or so gallons, the engine has coolant in the intake ,heads and block. to say you can drain it all complete is impossible, unless you find drain plugs on the side of the engine block and remove them, there is one on each side of the block, if you removed those you would get 90% of the coolant,with also draining the radiator. the only other way would be with a flush machine. i am a tech and the way you said the coolant was clean and you drained all you could then i would say if you keep doing it the way you are you will be fine, i drain mine the same way every year which is to soon for some but not me and i have never had a problem. the only time i drain the blocks at work is when people dont change the coolant for years and it gets rusted, then i remove the plugs. keep doing the flush the way you are and it will be fine, good day. have a good day.
