DaytonLax14

Would it be okay to just simply drain the radiator and fill with new coolant as opposed to draining the block, radiator, and doing a flush?

Reason why I ask is my coolant looks almost clear so I'd like to get some fresh fluid in there and I can't for the life of me get the block drain plug out. I don't want to flush the system without the drain plug out since there will be just plain distilled water sitting in the block while I fill the radiator with a 50/50 mix and it will throw off the ratio.

Martian

Probably, but if you're going to go that far anyway... why not go all the way

mbb

well, since the radiator only holds about half the system volume, drain and fill still leaves half old coolant in there.

Or something like that. I dont remember actual #s.

Now old coolant isnt really an issue for some. But if I wanted to get it all out, this is what I have done.

Heres what you do. And you can do the math based on the volume of radiator and total system.

Drain radiator, add distilled water. Start engine and drive around WARM so it circulates and mixes radiator and block for 10 minutes. Thermostat has to be open to mix. Drain radiator again.

Do this.....several times.

1st time= you are now 25% conc
2nd time= 12.5%
3rd time= 6%
4th time =3%
5th time =1.5% This is good enough for sure.
etc

Dispose of the old coolant/water properly. Dont leave anywhere animals could drink it.
Ive seen people on youtube flushing to ground with hose, thats awful as the block still holds 2.5 gal of glycol solution.

Refill with straight coolant - you will be ~50%
run and drive around to mix same as before.


5 drains at 2.5 gal each, is 12.5 gal , a couple of buckets of coolant/water

DaytonLax14

Do you need to leave the coolant cap off/loose to let air escape?

mbb

Not on my 5.4
Theres minimal air trapped.

moto823

I couldn't get the plug out either. Rather than dig myself a hole, I chose option B.

Option B:
Dont remove the plug
Remove both radiator hoses
Remove the thermostat, and reconnect the upper hose and elbow
Flushed through the motor with a garden hose, or just blow through if your not gonna do the flush.
Replace the thermostat (don't forget)
Reconnect the lines and fill.

white89gt

When I did my F150, I was AMAZED at how well the fill process went. No burping was necessary at all. I personally think it's due to the coolant being filled into the lower radiator hose. If you've owned a 4.0 Ranger or Explorer, you'll know just how big of a PITA it can be to get the air out of a cooling system.

Jbrew

Replying to a few earlier posts or sentences within. As mention previously, yea, just blow it out (go easy on the pressure.) I'd never flush w/garden hose personally, you can contaminate the block and most likley will, in fact you'll contaminate more than that unless your garden hose pumps distilled water.

The plug can be a PITA unless you can get an impact on it.