I am going to replace old antifreeze with zerex g5. What is the best way to flush system of old coolant? Thanks for your help

 

Here is the write up I found, it covers everything:

<!--StartFragment --> Okay, it’s time for me to do what I’ve been telling you to do. Change my coolant to be sure I get out all the green coolant and have nothing in there but gold antifreeze and distilled water when I get done.


<LI>Get ready.

Go to the store and buy 4 gallons of Zerex G-05 gold antifreeze. Go to Wal-mart and buy 20 gallons of distilled water. Go to my auto parts store and buy a coolant filter replacement element for my aftermarket coolant filter system.

If you don’t already have a cooling system flush kit installed, then go to almost any auto parts store that sells Prestone antifreeze and buy a Prestone flush kit. It’s only a few bucks.

If you haven’t already done it, then you’ll also need a new lower and upper radiator hose and a new thermostat. I did that last time, so I won’t do it again yet.

Tools needed include:

- a large pair of “water pump” pliers for removing the upper radiator hose from the thermostat housing
- a 3/8th inch rachet with 6” plus 3” extension and an 8mm socket to remove the bolts that hold down the thermostat housing,
- a 5-gallon bucket. If the bucket won’t fit under the radiator petcock and still have room to open and close the petcock, then I’ll also need a pair of ramps to raise the front of the truck a bit.
- a kiddie wading pool about 4 or 5 feet diameter and several inches deep.
- something to dip the water out of the kiddie pool and into the 5-gallon bucket. Maybe a 2-quart saucepan?
- a garden hose that will reach from the faucet into the engine compartment of your truck.
- a clear glass canning jar or plain water glass
- a funnel for pouring gallon jugs of liquid onto the Degas bottle.
-If you must haul the used antifreeze to somewhere other than your bathroom to pour it down the toilet, then you'll need a bunch of empty one-gallon milk jugs or water jugs. (Most jurisdictions allow you to pour used coolant down the toilet.)

<LI>Drain

Remove the radiator cap from the Degas bottle.

Drain the radiator into the 5-gallon bucket. Stop it from draining at about 3 or four gallons and empty the bucket by properly disposing of the used antifreeze. Then finish draining the radiator. You should get a total of about 5 gallons out of the radiator petcock..

If you have one, remove the coolant filter element and dispose of it. If you have a shut-off valve on the coolant line, be sure you leave it open so the lines will flush.

Place the kiddie pool under the front of the truck to catch any leaks and drains.

Remove the upper radiator hose from the thermostat housing (this is a heck of a lot easier said than done!). Remove the thermostat housing. Remove the thermostat. Install the thermostat housing without the thermostat. Install the upper radiator hose.

Install the flush “T” on a heater hose. Connect the garden hose to the “T”.

<LI>Flush with tap water.

Turn on the water to a low pressure but enough to run into the system faster than it drains out of the petcock. Too much pressure will damage the heater core. The water will begin draining from the petcock.

Watch the Degas bottle, and as soon as you see water begin to rise into the Degas bottle, crank the engine. Let the engine idle for a couple of minutes, then kill the engine. Turn off the water. Let the water drain from the petcock (and maybe some from the coolant filter base).

Dispose of the water in your catch basin (kiddie pool) and get ready for another cycle.

Turn on the water and wait until the water begins to rise in the Degas bottle, then crank the engine. Let the engine idle for a couple of minutes, then kill the engine. Turn off the water. Let the water drain from the petcock. As the water drains, catch a glassful and notice the color. If there is even a hint of color in the drain water, we need to flush it again with tap water from the garden hose.

Dispose of the water in your catch basin and get ready for another cycle.

After your drain water is nothing but clear water, then replace the kiddie pool with the 5-gallon bucket. Disconnect the garden hose and close the flush ”T”. Close the petcock. If you have an aftermarket coolant filter, install the new coolant filter element. (If you don't have a coolant filter, now is an excellent time to install one.

<LI>Flush with distilled water

Pour in 4.5 gallons of distilled water. Crank the engine and let it idle for a couple of minutes. Kill the engine and drain the radiator. Don’t try to rush the draining. It will take awhile to drain out all 4.5 gallons you just poured in.

Repeat that last step three more times – until you have poured in, circulated, and drained out a total of 18 gallons of distilled water.

<LI>Button it up.

Replace the thermostat, the thermostat housing, and the upper radiator hose. Be sure the thermostat housing bolts are good and snug, and the hose clamp is moved down to it’s original position on the hose. If you dropped a bolt and it disappeared into the bowels of the area around the water pump, then go to the Ford house and buy another one. Expect to pay more than $5 each for those 15 cent bolts. (Don’t ask how I know this. )

<LI>Filler up.

Pour in 4 gallons of gold antifreeze. Top off with distilled water. I just barely got the 20th gallon of distilled water open when mine was full. But after driving it to town a couple of times, some of the air bubbled out and it took a bit more. Hang on to that last partial gallon of distilled water for later additions.

Finally, that job is done. And it should now be good for at least 50,000 more miles with no coolant maintenance.

By using all 4 gallons of antifreeze, my concentration is about 57 percent antifreeze. That’s good enough for some very cold country.

<LI>Options I didn’t use.

If you remove both block plugs as well as draining the radiator, the tap water flush should not require as many cycles to get all the color out of the system. But that is a PITA, so I didn’t even think about it.

If you replace gold coolant with gold coolant, you would do it the same exact way - except your drain water will have a gold or tan/brown tint instead of a green tint.

If you replace green coolant with green coolant, you would also do it the same way, except at the very end you would add 3 pints of supplemental coolant additive (SCA) right after you poured in the antifreeze - before you topped off with distilled water.

If you want the 50/50 mixture of antifreeze and distilled water most experts recommend, then pour in only 3.5 gallons of antifreeze instead of all 4 gallons. Then fill the half-empty gallon jug of a left-over antifreeze with distilled water, and mark the jug "50/50". Then you’ll have topping-off mixture for future use.

If you replace the top radiator hose, be sure the new one is for trucks with two altenators. Then it will go around the fan belt instead of through it.