I'm getting ready to replace the coolant for the first time in my 2015 5.0. When you drain the system from the radiator drain, how much coolant will remain in the block? In other words, how much will you add to fill the system up? Thank you!

 

To not assume every vehicle is 100% equal. Determine the amount of coolant the system holds. Measure what you drained from the radiator. The difference is how much you will need to add.

If you intend to 'flush' the system, this is not a flush. You will have a mix of antifreeze already in the block.
At this point, do rough math as I suggested above and purchase premixed coolant and top off accordingly.

If you 'flush' and had water only in the block, my instructions would be different.
It sounds more like you are draining the radiator and refilling the radiator. Safest bet is to add premix to an already premixed system. Otherwise you may not be able to add the appropriate amount of water or antifreeze. Yes, some of the block will drain back too. I don't know where the thermostat is in these motors though. If they are low, and thermostat is closed, the block won't drain much (my last vehicle has a bottom of block thermostat).

Alternatively: Buy 2 gallons of the correct anti-freeze.
Drain the radiator -measure the amount of loss.
Lets pretend you drained 3 gallons. You will need to add 3 gallons. Therefore, you could theoretically mix your own by mixing 1.5 gallons of water with 1.5 gallons of antifreeze but you'll need a big bucket for that. You will have 1/2 gallon of antifreeze left to store when you've finished.

 

Thank you so much!

I plan on switching to the yellow coolant, and plan on flushing. I typically remove the thermostat, and fill the system with distilled water (I'll find the answer to my question here). I run the engine for awhile, with the heater on. I then drain the system. I repeat doing this, until what I drain is clear, and I know there is only distilled water in the block.

 

Ahh okay.

What I would do then is determine the capacity the system holds.
Lets say it take 18 quarts. A 50/50 mix wold be 9 quarts of anti-freeze and 9 of water. You have 'some' in the block, who knows how much and who cares. You know you need 18 total quarts but you know you have zero anti-freeze. Pour in 9 straight quarts of anti-freeze and top off with water. Nine fresh quarts of anti-freeze plus the water in the block and the little bit of water you add after will get you to 18 quarts.

When full you're done. Mostly. Leave room, but make sure you can check with a hydrometer. Add water/antifreeze until you reach your desired mix.

Do the math accordingly -I have no idea the full capacity. I'd have to go all the way out to the garage to look in my owners manual. LOL

 

Thanks again! According to the owner's manual, the capacity is 15.9qts. I plan on using 2 gallons of coolant I'm hoping it will take more that 2 gallons to fill it up after draining. I will do a 50/50 mix to fill the reservoir when the system is about full.

 

Enjoy!

 

I have found that most vehicles have roughly 50% coolant capacity in the block. I do the same as you - drain, fill with water, circulate, drain until there is nothing but clear water in the block. I just did my Corvette last year and it worked out at my general rule of 50%. The wife's Charger, my Avalanche, my mother's Saturn Vue, my old Sonoma - all worked out the same.

 

Thank you! When I measure it, I'll post it!

 

My water pump started leaking at 96,000......2016 5.0. Motorcraft replacement WP was only 74$ at Rockauto- not bad at all!

When I pulled out the water pump, like 3 gallons of coolant came gushing out of engine as expected.

If you are at a higher mileage point, consider changing the water pump too since all that new coolant comes out whenever the WP is replaced.

 

Thank you for your suggestion! Did you drain the radiator before pulling the WP?