Coolant flush & fill

[thebrakeman]

With searching, I've only found bits of info about doing a full coolant flush and refill, but no good how-to. I have the V8 with aux HVAC, which manual says is a 15.9qt system (just shy of 4 gallons). I have 2 gallons of Prestone Ext. Life concentrate, and want to flush as much as necessary to get all of the old/original coolant out.

I just did this on my Mazda3, but it's only a 2 gallon system. Could get a bit more than 1 gallon out with each radiator drain, but still took 5 drains to get sufficiently clear.

I understand about 1½ gallons will come out of the Mounty, but that leaves 2½ still in the engine and lines. That will take a lot of fills/drains to properly flush. Is there a block drain somewhere to get more coolant out? Or is there a particular hose near the bottom of the engine that I can pull off to get more out? If so, how much more should I be ready for?

PS - I'm not able to do a constant flush, as I don't have enough pans to catch that much fluid, and I'm not going to drain into the storm sewer.

 

[Tech By Trade]

Lol, probably no good guides because the system gets compleatly drained every 2 years when you have to change a cracked radiator.

 

[thebrakeman]

Well, I guess I'll just knock on wood. I must have 1 of the few good stock radiators.

Anyone know about how to get more than 1½ gallons out at a time?

 

[Flag Gibby]

When I drop the main bottom radiator hose on mine into a 5 gal bucket (disconnect at the radiator so that both openings feed into the bucket), I get what looks to be around 5 gallons. Literally almost to the very top of the bucket, which tells me that is all you should need to do on yours to get the system to completely empty. I also pull the radiator hose from the top of the t-stat housing (after I let the bottom drain some) in order to allow everything to easily flow down and out the bottom. When I refill I always remove the top of the t-stat housing (t-stat too) and fill from there first until it comes out the top, put back in the t-stat, back on the housing and fill the radiator until the coolant almost comes out the upper hose. Then I put the upper hose back on and finish filling. With everything closed up and coolant in the overflow tank, I will start the car put the heat on max for the front and rear and run the vehicle for about 10 minutes to get it hot enough to open the t-stat. Shut the vehicle down after that, carefully remove the radiator cap to make sure it is full and top off if not. Then I will just check it a couple of days later to just make sure that the overflow tank doesn't need to be topped off to the full cold position.

 

[thebrakeman]

Strange that you can get a 5-gallon bucket full from a 15.9qt system. I'll bet their 15.9qt doesn't include whatever is in the overflow.
thanks

 

[Flag Gibby]

That's what I thought too the first time I did it since I was afraid that the coolant was going to overflow out of the bucket and make a mess all over the garage. I really think the key to getting all the coolant out is pulling the t-stat which allows the engine block to no longer be pressurized. Luckily, I had planned on using 4 gal. of a final 50/50 mix so I had an extra gallon of concentrate and distilled water on hand for topping off vehicles when needed. When I got done I only had about 1 gal of mixed 50/50 on hand for future use.

 

[thebrakeman]

So did you bother with a water-only flush? Or just let it all drain really well and refill with concentrate/distilled? Part of me would like to flush out the lines to the rear system, which I doubt would get drained.
I'm at 108,000 miles on the original Ford coolant (as far as I know).

 

[Flag Gibby]

I didn't bother with a water only flush because I didn't see much buildup of contaminants on the radiator core or anything floating around in the bottom of the about 5 gallons of factory fill that came out.
The rear lines should drain out pretty good with my method (proof is in how much coolant you collect in the bucket), but you can always jack up the rear of the vehicle to ensure that they empty out if you are concerned.

 

[bschnur]

Great info, I need to flush my V6 and the question is, who will take the old anti-freeze when your done with it? I know where to take back old oil, but no one seems to want to except old anti-freeze. Thanks

 

[thebrakeman]

I had 5 gallons of various concentrations from my Mazda3 flush/refill. I took it to a quick oil change shop just yesterday, and they took it all.