Need to flush my coolant system

[Tynan918]

How do I flush my whole coolant system?

I know that there are drain plugs on the side of the engine to drain the water out of the engine block and there are plugs on the radiator and I can remove all the hoses, but how should I flush it out?

With a garden hose ?

 

[Tynan918]

Just ran the motor again with the radiator cap on for 20 minutes revving it up every so often and let it cool off to check the levels and condition and it's all green and free of rust but I'm stumped that I've only added about 1 1/2 gallons of the coolant mixture and the radiator is still showing full...even with the reservoir tank at the full line.

 

[CopperNick]

There is something of a second stage to your flushing of the coolant system and that is dealing with the remaining coolant that is in the heater core and lines should you happen to have one/them. Because your motor has a thermostat, it's presence creates a natural roadblock to getting a thorough flush. When you disconnect the upper hose, all that comes out is whatever is in the upper tank and that hose. Having the t-stat in its housing on the block prevents any further movement one way or the other.

There is a fitting adapter available, I think, from Prestone, that gets inserted into one of the heater hoses that lets you attach your source of water to it. That way the flush circulates through the top end and then down through the block and out the lower hose. it is also a good way to vent the heater hoses to expel air in the system during a refill or if you are getting no hot air from your heater system.



Nick

 

[ck80]

Just ran the motor again with the radiator cap on for 20 minutes revving it up every so often and let it cool off to check the levels and condition and it's all green and free of rust but I'm stumped that I've only added about 1 1/2 gallons of the coolant mixture and the radiator is still showing full...even with the reservoir tank at the full line.
View attachment 206134

You've got several variables:

1) during your flushing in and out of engine block, all you did is replace rusty coolant with plain hose water. But that volume counts against your 4 gals. So subtract about one, and go down to 3.

2) the various cycles of 'burping' the system of air in various places including your heater core and rad hoses, will draw in a little at a time.

3) various owners may have replaced the factory radiator for one of a different size - smaller tanks and/or smaller core size. This impacts volume.

4) you sound to still need to install the overflow tank, which, if filled towards the max cold line is going to take the better part of half a gallon or so.

Once the system is closed, with a full overflow, and run to full hot temp for a bit don't be surprised to see the overflow drop a little more and need a top off.

But again, don't forget, you had that 1 gallon of straight unmixed water in your block to start with....

 

[Tynan918]

You've got several variables:

1) during your flushing in and out of engine block, all you did is replace rusty coolant with plain hose water. But that volume counts against your 4 gals. So subtract about one, and go down to 3.

2) the various cycles of 'burping' the system of air in various places including your heater core and rad hoses, will draw in a little at a time.

3) various owners may have replaced the factory radiator for one of a different size - smaller tanks and/or smaller core size. This impacts volume.

4) you sound to still need to install the overflow tank, which, if filled towards the max cold line is going to take the better part of half a gallon or so.

Once the system is closed, with a full overflow, and run to full hot temp for a bit don't be surprised to see the overflow drop a little more and need a top off.

But again, don't forget, you had that 1 gallon of straight unmixed water in your block to start with....

I've finished the job, I flushed and replaced rusty water with new coolant. Yea more than likely the previous owner swapped for a smaller radiator, which means I can return the 2nd gallon of antifreeze back to O'Reilly's. I still have a half gallon of the mixture I made.

 

[Bonnewagon]

Do you have one of those inexpensive coolant testers? That is the final decider. I have tested crappy looking coolant and found it to be perfectly capable of protecting the engine both hot and cold. Dirty is dirty but is not an indicator of protection. Even after a flush- test and be sure. Adjust as necessary.