Coolant flush on Ecoboost engine

[Walt]

I've replaced all the other fluids on my Mustang but it's the first time I'm doing coolant on any car. The stock coolant is about 7 years old now and has seen some heatcycles from track driving so I figured it's a good idea to replace.

Is it as simple as :
1. draining the old fluid from the drain plug on the radiator
2. fill it back up with distilled water, run the engine for a couple of minutes with the heater on max
3. drain it again (when the engine is cold)
4. fill with new Yellow coolant, run the engine again with heater on max until it is hot and stops bubbling air?

Is the overflow tank the highest point on the Ecoboost engine or is there some port we have to vent to bleed the air?
Is there any special flush chemical I need or something I'm forgetting?

Those who track their car regulary (and on tracks where coolant is allowed) is there any special maintenance period for coolant like other fluids? My car doesn't have that much miles and the coolant looks okay but because of the age I think it's best to replace.

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[CoolRod]

That is the exact procedure I just performed on my GT. Except I flushed it about 4 times using distilled water then refilled with 50/50 anti-freeze/water. Super easy just don't remove the drain plug all the way otherwise you will end up with a huge mess of coolant.
The owners manual says to replace coolant every 6 years or 100k miles. I only have 37k miles but the car is over 6 years old.

 

[BluePonyGT]

Can I ask how thorough all of you were getting the old fluid out?

I haven't touched mine until this last weekend. I started noticing coolant coming out of the weep hole in the water pump at work on Friday, so I decided to tackle all of it at once starting with the actual coolant flush before I replaced the pump and gaskets, etc. I got an OEM pump from the local ford parts counter, plus 2 gallons of yellow concentrate from Motorcraft at the same time.

I also bought 8 gallons of distilled water (because I'm an engineer and I don't do anything half-way), proceeded to drain the system with the tank cap off, but only got out about a gallon out of the system. I replaced it with distilled, ran the car with the heater on max (the air NEVER got hot by the way) all the way to operating temp, shut the car off, drained again, but only got a gallon, but still red/orange. Then I let the car cool down, put another gallon of distilled in, repeat.

I've now done this 5 times. Still getting coolant out (although it's light pink finally), still running the car to operating temp, but no heat out of the heater on full blast so I must have air in the system and it's not self-bleeding. Fluid is always hot when I drain it.

I even moved the car so the back was up in the air - still getting 1 gallon out at a time and it's taking forever to get all of it out...

Down to 3 gallons of distilled left. This can't be normal. I feel like I'm missing something.

Oh by the way get a piece of 5/16" rubber hose to put on the drain nipple below the drain plug, and yes don't open it all the way. Whoever said be careful with this is right. Coolant will shoot out of that hole right on your passenger side wheel.

 

[CoolRod]

You will never truly get it all the old coolant out flushing it this way. But in the end, it's better than nothing. The only true way to completely flush it is to take it to a mechanic who has one of those machines that will flush out your cooling system. Something like this:

https://www.bestbuyautoequipment.com/coolant-flush-and-fill-machines-s/439.htm

 

[Walt]

Can I ask how thorough all of you were getting the old fluid out?

I haven't touched mine until this last weekend. I started noticing coolant coming out of the weep hole in the water pump at work on Friday, so I decided to tackle all of it at once starting with the actual coolant flush before I replaced the pump and gaskets, etc. I got an OEM pump from the local ford parts counter, plus 2 gallons of yellow concentrate from Motorcraft at the same time.

I also bought 8 gallons of distilled water (because I'm an engineer and I don't do anything half-way), proceeded to drain the system with the tank cap off, but only got out about a gallon out of the system. I replaced it with distilled, ran the car with the heater on max (the air NEVER got hot by the way) all the way to operating temp, shut the car off, drained again, but only got a gallon, but still red/orange. Then I let the car cool down, put another gallon of distilled in, repeat.

I've now done this 5 times. Still getting coolant out (although it's light pink finally), still running the car to operating temp, but no heat out of the heater on full blast so I must have air in the system and it's not self-bleeding. Fluid is always hot when I drain it.

I even moved the car so the back was up in the air - still getting 1 gallon out at a time and it's taking forever to get all of it out...

Down to 3 gallons of distilled left. This can't be normal. I feel like I'm missing something.

Oh by the way get a piece of 5/16" rubber hose to put on the drain nipple below the drain plug, and yes don't open it all the way. Whoever said be careful with this is right. Coolant will shoot out of that hole right on your passenger side wheel.

The heater not getting hot probably means there is air in the heater core.

Not sure if you can do anything about the amount of coolant that comes out the car. To avoid air in the system I'm planning to use an airvac system. I've already bought a tool (oemtools 24444) for this. Since air can create hotspots and possibly engine damage, I'm not going to bother with the old school way of doing it, these tools aren't that expensive for the peace of mind and easyness.

Once it stops freezing I'm going to drain all the coolant I can, refill it with only distilled water and drive it around for a while. Drain it and repeat once more. Finally I'll just fill half the coolant spec with the yellow concentrate and the other remaining half with distilled water. This way I'm sure the 50/50 ratio is kept, since there will most likely be water left in the system.

Doing the flush with distilled water twice is probably overkill though, I just like being thorough.

 

[BluePonyGT]

Just finished this on Monday. Decided to do what you did, but decided to turn it into an experiment of course: How many gallons of distilled would it take to get as close to clear as possible (without using any forced flushing system) until I felt it was “good enough”?

For me it took 8:

I know this is silly but I learned some things about this cooling system in the process. I learned you only get heat while running distilled to operating temp if you drive around a bit to get the air to bleed. Sitting on the speed ramps wasn’t going to let the system self bleed even with the expansion tank at the highest point, which this system actually does pretty well. I measured exactly what I took out, so by the time I had most of the coolant out it was a matter of calculating how many quarts in the system vs quarts of concentrate to put in like you described +\- some 50/50.

But yes, there’s no way I was going to get ALL of the old coolant out with this method. But you’ll get most of it.

 

[Walt]

Finally got around doing this, but how did you all remove that damn petcock drain valve on the radiator? Mine is really stuck and I can't use pliers on that crappy plastic part.

EDIT: Couldn't get it loose by hand so I quickly designed and 3D printed a little adapter for use with a wrench. I'll share it here in case anyone needs it. Handy to tighten it up again too.

 

[Walt]

Finished it this weekend. Took me about 20L / 5 gallons of distilled water for it to drain clear.

After filling up with distilled water I ran the engine for 15 minutes until at operating temp, with the heater on max. I repeated this 4 times and each time it took about 6L / 1.5 gallons of distilled water.

For the last refill, I used the actual Yellow coolant concentrate. I'm glad I got the concentrate because most of the distilled water will be left in the engine and can mix with this. Not much more distilled water could get in after the concentrate so a premix 50/50 would get skewed ratios.

Problems I encountered:

• The drain valve was on really tight and I couldn't remove it by hand or use pliers in fear it would break. I designed and 3D printed an adapter to use with a wrench.
• I used a 12mm clear hose for the petcock, but most of the fluid came via the valve screw itself so it still made a mess.
• Next problem was that I used a vacuum tool to refill the fluid, but there is a vent hole in the expansion tank right under the coolant cap. This is a square hole and I didn't have any plug that fitted it. So buy yourself some different kinds of vacuum plugs if you go this way. I solved it by using some detailing clay and sealed the hole.

Other than that the process is pretty easy and I'm glad I did it myself instead of taking it to the shop.

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