35 Step Guide To Changing Out Engine Coolant In Most Vehicles

[Buford T. Justice]

The following directions to changing out your engine coolant require the following parts...

- 1 Prestone Flush 'N' Fill Back Flushing Kit.

- Tools to install the Prestone Flush 'N' Fill Back Flushing Kit. Usually a pair of scissors and a socket head screw driver of the right size are all you need.

- 1 bottle of Prestone Super Radiator Cleaner. For cooling systems with a capacity of more than 12 quarts, use 2 bottles.

- About 15-20 jugs of distilled water. You can buy these at any Wal-Mart for about $.60/jug. 20 jugs = ~$12. More jugs of distilled water may be needed.

- At least 2 jugs of the coolant required for your vehicle. Be sure to verify what type of coolant your vehicle requires in your owner's manual. If your vehicle uses the old green type coolant, your can safely use Zerex G-05 which is the direct replacement for the old green type coolant. Each jug generally holds 1 gallon of coolant. It takes 4 quarts to equal 1 gallon. If your cooling system capacity is 12 quarts, you will need about 7 quarts of coolant to achieve about a 55% coolant to 45% distilled water ratio. More jugs of coolant may be needed.

- 1 jug of pre-mixed 50/50 coolant to distilled water using the same brand and type of coolant you selected. You can also make your own if you have enough coolant and distilled water left over (look below the following directions).

- A coolant tester.

YOU ASSUME ALL RESPONSIBILITY USING THE DIRECTIONS BELOW. READ THEM BEFORE DOING ANYTHING. I ASSUME NO RESPONSIBILITY WHATSOEVER IF YOU RUIN YOUR CAR.

1) With a cold engine, remove the coolant overflow tank hose from the radiator if you can.

2) Remove the radiator cap.

3) After draining the coolant overflow tank, radiator, and engine block (if possible), install the back flushing tee to the heater core inlet hose (not the outlet hose). Be sure to follow the directions PRECISELY on the back flushing kit when installing it.

4) Put the engine block drain plug back in if you removed it in Step 3.

5) Be sure the water coming out of your garden hose is CITY water (NEVER USE WELL WATER) and that the water comes out of the garden hose in a nice steady stream. High pressure is not needed. You want the water to come out of the garden at about the same speed as water drains out of an open 1 gallon water jug turned upside down. Turn the water off. Hook the garden hose to the back flushing tee using the adapter that comes with the kit. Turn the water on.

6) Wait for water to come out of the radiator drain plug hole and the radiator cap hole.

7) Turn your engine on (always with the heater on HOT and fan speed on HI for all these steps).

8) Run the engine until the water comes out clean & clear from the radiator drain plug hole and the radiator cap hole. Once the water comes out clean & clear, run the engine for 15 more minutes.

9) Turn the engine off, remove the garden hose from the back flushing tee, and put the cap back on the back flushing tee.

10) Put the drain plug back into the radiator once it has completely drained.

11) Open any air bleeder valves you may have.

12) Fill the radiator with distilled water.

13) Put the radiator cap back on.

14) Start the engine.

15) Quickly get back to the air bleeder valves. When fluid comes out of them in a steady stream, close them.

16) Wait for normal engine operating temperature to be reached then let the engine run for at least 15 minutes. Keep your eye on the temperature gauge.

17) Turn the engine off.

18) Wait for the engine to cool.

19) Remove the radiator cap, open the radiator drain plug, and let the radiator completely drain.

20) Repeat Steps 10-19 at least 2 more times. Preferably 5 times total.

21) Put the radiator drain plug back in.

22) Pour in at least 1 bottle of Prestone Super Radiator Cleaner. Use 2 bottles of Prestone Super Radiator Cleaner if the capacity of your cooling system is more than 12 quarts. Read the bottle and your vehicle owner's manual to verify.

23) Repeat Steps 11-18 once.

24) Rinse out the coolant overflow tank with distilled water until all the old coolant in it is gone. Re-hook the coolant overflow tank hose to the radiator then fill it to the cold mark with distilled water.

25) Drive the car on and off for 3-6 hours. Be sure to keep the radiator full of distilled water and the coolant overflow tank filled to the cold mark with distilled water. Keep a constant eye on both!

26) Keep an eye on the back flushing tee where you cut the heater core inlet hose to install it to be sure it is not leaking. If it is, tighten the clamps carefully until you are sure it isn't leaking anymore. Don't over-tighten the clamps or you may break the back flushing tee.

27) Repeat Steps 1-20.

28) Put the radiator drain plug back in.

29) Fill the radiator with the recommended coolant specified in the owner's manual for your vehicle. If your vehicle uses the old green type coolant, your can safely use Zerex G-05 which is the direct replacement for the old green type coolant. Be sure to open any air bleeder valves.

30) Optionally but recommended, you can remove the coolant overflow tank and clean it out with HOT water and dish soap in your bath tub. Put a little bit of dish soap inside the coolant overflow tank and fill it with HOT water. Shake it well then drain out the soapy water and soap suds. Keep rinsing it out with HOT water until no more soapy water or soap suds come out of it. Then rinse the coolant overflow tank out with distilled water at least 3 times just to be sure there is no more soap left in it. Reinstall the coolant overflow tank. Be sure to hook the coolant overflow tank hose back up to the radiator.

31) Fill the coolant overflow tank to the cold mark with the recommended coolant.

32) This should give you 50-55% coolant to 45-50% distilled water ratio in your entire cooling system.

33) Repeat Steps 13-18 once.

34) Check the level of coolant in the radiator and in the coolant overflow tank. If you have a 12 quart cooling system and you know you have used 7 quarts of coolant so far, just top off with distilled water. If not, use straight coolant.

35) As the next few days go by, top off the radiator and the coolant overflow tank to the cold mark using the pre-mixed coolant. Use the coolant tester to verify you have the proper mixture of straight coolant to distilled water. Use the chart on the back of the coolant jug to verify. If you didn't use enough coolant, you can drain a little bit of weak coolant out of the radiator by opening the radiator drain plug then closing it after a little bit of the weak coolant has drained out the the radiator. Don't drain the radiator dry! Top off the radiator with straight coolant. You can also do this if you used too much coolant by draining the radiator a little bit and topping off with distilled water.

If you didn't buy a jug of pre-mixed 50/50 coolant for topping off your cooling system, you can make your own if you have enough coolant and distilled water left over. In one of the empty coolant jugs, be sure at least 1.5 quarts but no more than 2 quarts of distilled water is in the jug then fill the jug with coolant to the 4 quart line on the jug. Shake it well and use this for topping off the coolant until it is time to change the coolant again.

After doing an entire cooling system coolant change using the steps above, a lot of folks just drain the radiator once a year, usually in mid Fall before it gets below 45 degrees F at night, then fill the radiator with pre-mixed coolant so they never have to change out the whole cooling system again unless mechanical problems make it necessary to do so if they develop..

GET INTO THE HABIT OF CHECKING BOTH THE RADIATOR AND THE COOLANT OVERFLOW TANK TO BE SURE THEY ARE FULL OF COOLANT. I usually check mine at least twice a week. Also keep an eye on the color of the coolant. If it looks different than when you changed your coolant, you might have a serious problem with your engine or you simply need to change the coolant once again due to impurities.

 

[jmacmaster]

quote:

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Originally posted by kanling:
Nice procedure. Mine's a little simpler because I don't use any radiator flush product. Only if the system was in poor shape already would I consider using a flushing chemical.

My procedure:
1. Drain existing coolant.
2. Refill with distilled water.
3. Run engine to circulate water and long enough so thermostat opens.
4. Drain water
5. Repeat steps 2-4 until the drain water is clear (usually 3-4 times).
6. Add non-diluted coolant so that the amount added is 50% of the capacity listed in the user's manual.
7. Top off with distilled water.
8. Top off with distilled water again after a few days if any air has burped out.

If I know the existing coolant isn't old and the system is already in good shape... then I don't even do a distilled water flush. I just drain and refill with a 50% coolant/distilled water mix.

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I mainly agree with the above, but have the following comments. In Step 1, you drain by opening the valve at the bottom of the radiator. In Step 3, turn the heater on, to high, to circulate water in the heater system. In Step 5, I think you need to drain 5-6 times. In Step 6 you may want to go up to 60% antifreeze if it gets 30 or more below zero F where you live. In Step 8, I check for air burps the same day, and also a day later and use the same antifreeze/distilled water mix as when I filled the radiator, in order to maintain that percentage.

I guess I don't understand the last paragraph. If the coolant is not old and the system's in good shape, why drain and refill any of it? And you'll only be draining and refilling what's in the radiator, not what's in the engine block, and about half the coolant's in the engine block.

 

[kanling]

Good details JMac. I agree totally.

My last paragraph would apply if you are doing drain cycles shorter than the true maximum life of the coolant. I mean, if you are staying well on the safe side of coolant life. In that case, the procedure is more of a "refresh" than a coolant change.

Basically, you are "strengthening" the coolant, even though half is still in the block. If the coolant truly has no life left in it, I recommend the full procedure.

 

[The Critic]

Buford,

I commend you on your thoroughness, but you can eliminate some of the steps:

1) Drain radiator
2) Refill with tap water.
3) Remove Block Drain Plug, but do not reinstall
4) Remove thermostat from its housing
5) Start Engine
6) Keep radiator filled while water is being pumped out of engine block. Keep doing this until discharge is clear
7) Drain radiator, reinstall block plug. (Shutting off engine first)
8) Take coolant capacity, divide by 2, and install amount of coolant concentrate into radiator. Top off with distilled water
9) Add 50/50 Premix to overflow bottle

I haven't tried those steps before, but I think it'll work.

This is the more conventional way:

1) Drain radiator (Don't worry about block plugs if they're inaccessible)
2) Refill with tap water.
3) Run engine w/heater on until thermostat opens up.
4) Drain radiator, and repeat steps until discharge is clear, usually 3-4 cycles.
5) Take cooling system capacity, divide by 2, and add that amount of concentrate into the radiator, and top-up w/tap water.
6) Top-up overflow bottle with 50/50 PreMix.

I personally do not use chemical flushes if the system is in good condition and has been serviced regularly in the past.

Btw, I change coolant when the system is hot.

 

[Buford T. Justice]

I wouldn't change any of the steps. You will get excellent results every time if you follow them.

Tap water is OK for the initial flush, but only use distilled water after that.

 

[kanling]

Nice procedure. Mine's a little simpler because I don't use any radiator flush product. Only if the system was in poor shape already would I consider using a flushing chemical.

My procedure:
1. Drain exising coolant.
2. Refill with distilled water.
3. Run engine to circulate water and long enough so thermostat opens.
4. Drain water
5. Repeat steps 2-4 until the drain water is clear (usually 3-4 times).
6. Add non-diluted coolant so that the amount added is 50% of the capacity listed in the user's manual.
7. Top off with distilled water.
8. Top off with distilled water again after a few days if any air has burped out.

If I know the existing coolant isn't old and the system is already in good shape... then I don't even do a distilled water flush. I just drain and refill with a 50% coolant/distilled water mix.

 

[oilboy123]

What works great is ice and salt in the coolant bottles. Just shake the living heck out of the bottle with the lid shut.

This will clean all the scum out.

 

[Winston]

The one possible problem with Critic's method is that my coolant system capacity is 9.5 quarts and the radiator only drains out 3.5 quarts.

So, this is what I did;

1. I drained the radiator and 3.5 quarts came out. Then topped up with distilled water. This left me with a 32% solution of coolant in my vehicle.

2.Warmed up vehicle. Then drained out another 3.5 quarts of coolant. Then topped up with distilled water. This left me with a 20% solution of coolant in my vehicle.

3. Warmed up vehicle. Then drained out another 3.5 quarts of coolant. Then topped up with 100% coolant. This left me with a 49% solution of coolant in my vehicle. At this point I have 72% New fluid in my cooling system.

The math ended up being a little more complicated than I thought it would be, but with excel it was pretty easy.

 

[Al]

Not trying to be funny but my procedure:

Drain coolant with the engine as warm as possible.
Refil with Antifreeze/Demineralized water.
Repeat procedure in another week.

 

[carock]

Wow, I don't know if it is really possible to legally perform this type of flush. You end up with 20 gallons of coolant/flush contaminated water to dispose.No shop could afford to do this. Also, the chemical flushes seem to create more problems than they solve IMHO. Maybe they are useful on some cars, but as a professional I could not risk using a chemical flush on a customer car. I wish I had known about coolant filters earlier, I would have recommended them to my clients with high mileage or classic cars.

 

[The Critic]

If the drained coolant looks fine, the idea of draining both the block and the radiator, followed by filling with fresh 50/50 Premix of new coolant is becoming more and more appealing. Repeating this a second time will replace as much coolant as flush, without the harmful environmental effects.

 

[Buford T. Justice]

I just dump it on the ground. The water from the drains dilutes it so much the harm is short lived. If you are really worried about it, just pour it into the toilet and flush.

 

[Al]

quote:

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Originally posted by Buford T. Justice:
If you are really worried about it, just pour it into the toilet and flush.

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Yes but if you have a septic tank, don't do it. Most municipial sysstems handle antifreeze.

Where did you get information on the stuff breaking down easily. Not doubting you. I am concerned that it would be bad, environmentally.

 

[Shannow]

Step 1, buy a packet of coolant test strips.

Step 2, test the coolant reglarly.

Step 3, change it first sign of degradation (i.e. long before the other 32 steps need doing).

 

[Buford T. Justice]

Al: I forgot about the septic tanks. Thanks for the heads up. I didn't say break down. I said dilute. After back flushing for about 10 minutes, I see no traces of coolant on the concrete or on the nearby ground where I am doing the flush at.

Shannow: You can obviously do that, but I and many others will not run it just testing it until the strips says it is degraded. Strips won't tell you how dirty the coolant is nor if there are any contaminants in it. Changing it every 2 - 3 years properly insures nice, fresh, clean coolant.

 

[The Critic]

If you do a complete flush/fill with the extended life coolant of your choice, and did a partial drain/fill (radiator only) every 5 years, you should be fine as well, since OAT coolants provide a near lifetime protection against corrosion.

 

[Buford T. Justice]

Absolutely. I plan on draining the radiators and overflow tanks and filling them back up with 50/50 to 60/40 coolant to distilled water in the cars I work on for my family every year.

 

[Winston]

quote:

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I just dump it on the ground.

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Are you serious? Do you know where your storm drain ends up? It only takes a very very small amount to contaminite/kill wildlife downstream.

The best thing to do is to take it to a houshold hazardous waste center. The next best is to dump it in your sink or toilet.

Jeez

 

[Buford T. Justice]

The ground is so much quicker. Seriously, I don't feel bad about doing it at all. Think about it for a moment...

For the sake of argument, let's say we have a cooling system that holds 12 qts. of coolant (50/50). So technically, that is 6 qts. of "pure" coolant or 1 1/2 gallons. By back-flushing the engine for 15 minutes using a garden hose of average pressure and a back-flushing tee on the heater core inlet hose with the radiator drain cock fully opened and the radiator cap removed and the engine running, I would guess an extra gallon of water is introduced to what is on the ground approximately every 15 seconds so that is 4 gallons of water per minute. A 15 minute back-flush is 60 gallons of water. That "pure" coolant is now so diluted with water that the hazard created by it prior to being diluted with the back-flushing water is meaningless.

 

[Winston]

quote:

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A 15 minute back-flush is 60 gallons of water. That "pure" coolant is now so diluted with water that the hazard created by it prior to being diluted with the back-flushing water is meaningless

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The year is 2006. Dumping chemicals on the ground is not appropriate. Try a 60:1 solution in your fish tank and see how long the fish live. Find me some source that defines an acceptable dilution rate for dumping glycol on the ground.