Coolant Flush

[alp]

Hi guys!
Can you please advise how to properly flush the cooling system?
Currently the system is filled with a green coolant and I want to replace it
with the OEM red one. I know that the simple drain and fill of radiator is not enough to remove all old coolant from the system. How do you do this?
Thanks

 

[BTO]

I have always used a Prestone flushing tee that connects to the heater hose and "backflushes" the system.

I am not sure if that is the best method. It does seem to do a complete job. It will leave some tap water in the system.

 

[alp]

This is my plan:

1. Drain radiator and measure the amount of drained coolant.
Calculate how much coolant left in the system. Let say X gallons.
2. Fill up with distill water and run for 10-15 min.
3. Drain
4. Repeat stets 2 & 3 two more times.
5. Now I have X gallons of the clean distill water left in the system.
6. Add the same amount of 100% antifreeze to make 50% mix.
7. Fill radiator to the top with premixed 50% coolant.

Is anything missing?

 

[TheDurk]

You need to bleed the air out. Keep running the motor until thermostat opens and adding mix to top of rad. Works better if front is slightly elevated. I run my front wheels up over the curb in my parking area to do this.

Also verify level on lines on overflow bottle once motor is cold following first drive.

 

[alp]

Thanks for the good advice Durk

 

[brian2sun]

Rather than diluting the system slowly, just pull the thermostat to get most of the coolant out of the block from the start.

 

[alp]

Did it today. Everything is okay.
Thanks everyone for advices.
I didn't want to mess with a thermostat seal/gasket and didn't remove it.

 

[sean2202]

The best way I found was to pull the thermostat and flush both ways. This gets all the crap out that gets stuck in crevices when you only flush one way. I flush every two years the inhibitors in coolant (any coolant) IMO break down overtime. I also add a bottle of this every year.

 

[Ehahn84]

This is my plan:

1. Drain radiator and measure the amount of drained coolant.
Calculate how much coolant left in the system. Let say X gallons.
2. Fill up with distill water and run for 10-15 min.
3. Drain
4. Repeat stets 2 & 3 two more times.
5. Now I have X gallons of the clean distill water left in the system.
6. Add the same amount of 100% antifreeze to make 50% mix.
7. Fill radiator to the top with premixed 50% coolant.

Is anything missing?

That's about it. Then burp the bubbles out when done.

 

[amalik]

The best way I found was to pull the thermostat and flush both ways. This gets all the crap out that gets stuck in crevices when you only flush one way. I flush every two years the inhibitors in coolant (any coolant) IMO break down overtime. I also add a bottle of this every year.

sean, can you add that stuff to existing coolant and it dissolves within? (i.e. doesn't increase the capacity if my radiator is already full?)

 

[sean2202]

sean, can you add that stuff to existing coolant and it dissolves within? (i.e. doesn't increase the capacity if my radiator is already full?)

This old timer that owns an old school radiator shop near me advised me of this. He must be 80 years old " Been workin on cars for 60 years all sorts of dissimilar metals in their now" He said its the only stuff that works. I use it now on everything once a year. I add it to my overflow. If its at full I would siphon a little out of overflow but probably wouldn't matter either way its a small bottle.

 

[kolelt]

Old thread but I want to share this video

https://youtu.be/D7dHF5Tc-ug

Hopefully it helps for some