Question about 2005 Mercury Grand Marquis

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Trouble draining coolant on 2005 Mercury Grand Marquis

Trying to change coolant on 2005 MGM. Cooling system capacity is 13.6 quarts. Drained system and measured coolant drained. It was 6 quarts. System was full and working fine prior to draining. Heater was on during draining. How do I drain the other half of my coolant? I even ran the engine for a (very) short time after only six quarts of coolant would drain out. That accomplished nothing. I drained the coolant from a single drain point, lower corner of the radiator on driver's side. Coolant ran out freely and was quite clean . .very little debris, etc.. I have since put the six quarts of old coolant back in. The coolant level comes right back up to the line . . up to normal. So when I drain this next time, how do I get the other half of the coolant to drain out?

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  • Frank Walker Feb 14, 2012

    In response to a question, I want to add that when I drained the coolant, the pressure cap for the overflow reservoir was removed and set aside. It was not in place.

  • Frank Walker Feb 14, 2012

    Thank you to Johnny Brown and to Jeremy W.. I really appreciate hearing what you guy have to say.

    I talked this over this afternoon with the manager at Autozone where I bought the anti-freeze. He mentioned use of a vacuum machine to remove (most of) the undrained coolant. We also talked about flushing, but flushing is NOT really my issue. There are several ways to flush the system and I'm confident I can accomplish that.

    Here's the problem, though:

    Any flushing I do must be done either with my well water or else with a very large quantity of purchased distilled water. When I started this job I wanted to end up with a 50-50 mix of Prestone and distilled water in the cooling system. I did not want to have my VERY hard well water in there.

    Inability to recover at least 80%-90% of whatever is in there makes this job a real challenge. Even if I flush out most of the old coolant, what's left behind is well water. For example, if I flush until it runs clean, then drain, I still am leaving behind over seven quarts of well water. Also, simply refilling with a 50-50 mix at that point is obviously not smart, since the residual water (well or whatever) will dilute that way down to where it's no longer even close to 50-50.

    So you see the problem is not flushing, it is removing whatever fluid remains after the flush. I DON"T expect to get it all . . I can live with a quart or two in the heater core, etc.., but I need to be able to get out more fluid than six quarts out of 13.6.

    I've been told the radiator drain point is the only one on this engine. The manager mentioned a vacuum system used by the shops. I can easily rig something up to **** out much of the undrained coolant. What I don't know is where to enter the system with my vacuum hose. If I remove the thermostat, can I get in that way, all the way down to the bottom of the block??

  • Jeremy W.
    Jeremy W. Feb 14, 2012

    Is this all worth it to save $80

    If there is water in the system now then you would drain the radiator and fill with straight coolant. That should get you really close. You would then check with a coolant protection tester to see if you needed more coolant or more water. You would then drain the radiator about a 1/2 gallon at a time and add water you needed and recheck.

    Or for about $80 and a half hour of your time just have it flushed at a reputable shop. Either a dealer or independent that you know does good work.

    As far as rigging a vacuum device that only works for filling an empty system. it will not work to remove fluid from the system. In order for that to work you would either need to wait fro the water in the block to evaporate or the block would have to "squeeze" the fluid out. That is not going to happen.



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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.

Posted on Feb 14, 2012

Testimonial: "Thank you, Johnny Brown . . very much. I have to confess I did not seek out or look for such plugs. It is because I had been assured they do not exist!! Obviously, now, in light of your post, I will search diligently for those plugs. You can rest assured of that. And, of course you are correct: such plugs would indeed solve my problem . . BIG TIME! Thanks again. Your response was, indeed, very, very, helpful!! I just hope I can locate the plugs. :-) "

  • Johnny    Brown
    Johnny Brown Feb 15, 2012

    Frank this engine does have drain plugs on the side of the engine block near the middle to the side of freezeplug, removing them9one on each side) would save you a lot of time. this would drain the block down.i work on these and i am sure there are plugs. this way you can do the 50/50 mix and not have well water in the system.


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The other half of the coolant is "stuck" in the engine. There is no way of getting this out unless you "flush" the cooling system. This is done with a flush machine.

Posted on Feb 14, 2012


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