Flushing with water and then fill with concentrate for desired ratio

[JR402]

Just wondering, do you end up with an acceptable ratio of coolant and water by using this method? I have drained and refilled many systems, but I have not done any with a full water flush. I also have only used the basic cheap antifreeze testers, are they good enough with the newer coolants?

I'll be working on an 2007 Mazda 3 2.0. It only has 48k miles on it and is new to me, and I don't know if the coolant has ever been changed. I was planning on using the Peak 10x coolant and I already have 2 gallons of the 50/50 premix. I was wondering if picked up just 1 gallon of the concentrate if it would be enough to complete this job? Not sure how much water will be left in it after draining it. thanks

 

[Kira]

One point is that you don't have to know how much water is left after draining. You'll do repeated rinses with just water so whatever's left is just water.
You halve the cooling system's stated capacity and pour in that much concentrate, assuming you want a 50/50 mix.
Then top it off using a gallon jug as your water pitcher. You do this to keep track of how much water you've added.
If the system holds over 8 quarts, you then bring it to full using the 50/50 premix.

Your car specs a 7.9 qt. cooling system on the Amsoil site.
Assuming that's correct, just install the gallon of concentrate and top off with water. You'll have slightly over 50% coolant; which is OK.

If you allow your system to drain and want to know how much water is left behind, you must close your drain and again fill with water noting how much you put in MEASURING CAREFULLY. When it's full, subtract what you put in from the stated capacity to see how much was left behind after your drain. This would be called a "subtraction method". IT's a lot of words but simple in practice.

Pouring 50/50 mix into a partially emptied system will result in an uncertain concentration. The remaining water will cut the 50/50 and result in a higher freezing point.

The concentrates are the way to go for ratio control.
However, in a clean system, all one needs to do is drain the radiator (and reservoir if you like) and refill with the correct 50/50.
It's the way it's done...drain & fills work just fine in systems which haven't been allowed to get filthy.

Assuming the 50/50 you have doesn't conflict with the coolant already in the system, I'd just drain the radiator and reservoir and refill.

You said you don't know what's in there so a complete water flush might be prudent.

One gallon of the concentrate or the 2 gallons of 50/50 you already have will be enough for the job assuming the capacity listed on the Amsoil site I used is accurate.

Go for distilled or DI water for your final flushes and mix. Some people live in regions where the tap water is usable for this. Many do not.
That's your call.

I read the once common floating balls tester is not the best for newer coolants.
This is secondary to your situation as you'll be making up your mix with care and precision.

 

[Malo83]

Just drain and flush several times till the water comes out clear then 1 gal of Prestone and done. Run the car to clear air, check water level next day and top off, no measuring.

 

[JR402]

Great information, thank you. Makes more sense now as far as adding half the stated capacity in concentrate and then topping off with water.

 

[eljefino]

If the math is challenging think of it this way, you have an 8 quart capacity, so you have 4 qts antifreeze in there.

You drain the radiator and get 6 quarts out, refill with water. Now you have 1 qt AF.

You run it for a day, then drain it again, get another 6 quarts out. Now 1/4 qt antifreeze.

Do the math-- 4 quarts of new antifreeze, plus .25 qt of old, divided by 8 qt capacity, is 53% coolant, good enough.

The floaty ball testers are hot garbage, do math, it's more reliable.

 

[Gyro Gearloose]

When I've done complete flushes in the past I drain the system and measure how much water it takes to refill. I compare that to the cooling system capacity found in the owners manual and assume the difference, X quarts, is how much that is held up in the engine block and heater system. Usually it is close to 1/2 the total system capacity.

After 3 or 4 drain and fills with clear water I presume the engine block has X quarts of clear water left in it and add an equal volume of pure antifreeze. Usually by the time I get the antifreeze concentrate installed the system is full, but if more coolant is required I top off with 50/50 mix. For cars that I can't buy concentrate, like my Honda, I just do a drain and refill and forget it.

I call this the low math approach.

 

[Urshurak776]

When I've done complete flushes in the past I drain the system and measure how much water it takes to refill. I compare that to the cooling system capacity found in the owners manual and assume the difference, X quarts, is how much that is held up in the engine block and heater system. Usually it is close to 1/2 the total system capacity.

After 3 or 4 drain and fills with clear water I presume the engine block has X quarts of clear water left in it and add an equal volume of pure antifreeze. Usually by the time I get the antifreeze concentrate installed the system is full, but if more coolant is required I top off with 50/50 mix. For cars that I can't buy concentrate, like my Honda, I just do a drain and refill and forget it.

I call this the low math approach.

This is what I do pretty much.

If I have had the car since new, I just do a drain and fill with 50/50 at 60K. Then again at 75K. Then again at 100K. Every 25-30K after that. Seems to work fine. Never had an issue.

 

[fantastic]

Just make sure to use the distilled water. Might take you a couple gallons but that's better then regular tap water in a cooling system.
https://www.walmart.com/ip/Great-Value-Distilled-Water-1-Gallon/10315382?athbdg=L1600

 

[JR402]

Just make sure to use the distilled water. Might take you a couple gallons but that's better then regular tap water in a cooling system.
https://www.walmart.com/ip/Great-Value-Distilled-Water-1-Gallon/10315382?athbdg=L1600

I remember the old guys used to just use water from the hose, probably still many that do it that way. When I got old enough to start learning stuff on my own and looking up info on the internet, I learned about using distilled water to mix with the antifreeze. That was probably around 1997 and thats what I've been using since then.

 

[TimeFlies]

If you are not flushing with distilled water only, you have contaminated the system with tap water, which is a bad idea.

 

[fantastic]

I remember the old guys used to just use water from the hose, probably still many that do it that way. When I got old enough to start learning stuff on my own and looking up info on the internet, I learned about using distilled water to mix with the antifreeze. That was probably around 1997 and thats what I've been using since then.

good deal, reminds me of the old hats always topping off their auto batteries with water too haha.

 

[slacktide_bitog]

That's what I'm going to be doing as I replace Dexcool/Deathcool with Peak 10x

The Lisle coolant funnel is awesome

 

[nate379]

I remember the old guys used to just use water from the hose, probably still many that do it that way. When I got old enough to start learning stuff on my own and looking up info on the internet, I learned about using distilled water to mix with the antifreeze. That was probably around 1997 and thats what I've been using since then.

That's all we do at work. Make thousands of gallons of antifreeze a week. DEF too.

 

[dumkid]

I've used hose water (and mud puddle water in an emergency)
With the hose water i flushed the system (i had the water pump and heater hoses and radiator removed) then I put it back together and added some distilled water and a gallon of concentrate. No problems yet.

Some coolant bottles just say to use clean water, while others specify distilled water.

 

[KrisZ]

Had that same gen Mazda 3. The system is either almost or slightly more than two gallons. The radiator will drain one gallon. So getting the final 50/50 ratio is super easy on these.

 

[ripcord]

If you are not flushing with distilled water only, you have contaminated the system with tap water, which is a bad idea.

It depends where you live. I fill with tap water more often than not. Our water is so soft that a kettle we've had forever has no buildup inside. Same with the boiler of our espresso machine when I had to work on it. The latest report from the water district said we have 9.4 parts per million of calcium.

 

[SHOZ]

I usually do a couple flushes with good water, then fill with a gallon of 70% then top off with 50/50. Gets me around 25F below.

 

[zulf200]

If using something like peak global or g05 or dexcool you can use the hose as long as its drinking quality. Dont use tap water to mix POAT coolants, they will precipitate out.

With your car the engine has no drain, the radiator only drains the radiator level and above. If you want to drain the block and head through the radiator drain, you will have to open the radiator drain on a fully hot engine.

The safest way I flush these mzr engines is to first run a cleaning agent like citric acid or oxalic acid, cool it off, then drain the radiator and remove one heater bypass line, the same one that terminates at the thermostat housing itself, (or just remove the thermostat, its the lowest part of the cooling gallery)

Then use a hose to push out all cleaning agent from everywhere and then use a funnel on the heater hose connections to pour distilled water (about a couple of gallons worth) to have the system ready for fresh coolant charging.

You can do the next step with 50/50 if you use an air blower or compressed air to blow out all water first before packing it up, or do the 50% volume concentrate filling and topping the rest with distilled water till you see about 80% of the specified volume has been charged in the system. Its a good idea to check with a refractometer after 3 or 4 temperature cycles.

I prefer to use the ford special dark green in these or kia/hyundai dark green or even honda/nissan blue. To keep original optics intact. But good old peak global works a treat, it has never let me down.

Good luck with your job.

Btw mazda3 use an pressure expansion tank, so the total volume is till its top line. On cars with a regular rad cap and separate expansion tank, the total volume includes the tank volume too. It be upto 1 liter or more and can really upset the mixture if you add a lot of concentrated coolant without subtracting the tank volume from the radiator/engine volume.