Drain Procedure:

1. Complete all preparation steps listed in the original post. If the engine bay is hot, wait longer before starting.

2. Remove the Undercover. Note the 3 bolts (12mm) at the front and 2 bolts (12mm) at the back. Also note the 2 push pin clips on the left and the 2 push pin clips on the right. Remove the bolts first. There is a trick to the push pin clips. Insert the thin tipped flat head screw driver into the clip's face groove and gently twist to pry the pin open. Don't be forceful with these plastic clips. See the second picture.

3. Locate the drain plug. Reference the picture in the first post. If you look in front of the passenger's front wheel well, you will find the drain plug sitting out of sight just over the metal subframe at the bottom of the radiator. You can reach it with your left hand without getting under the vehicle. Alternatively, you can remove the air intake scoop by removing 2 bolts at the front (10mm). Look down towards the bottom of the radiator's left side. The second picture shows the drain plug from above.

4. Place a wide 8 Liter capacity container on the floor below the drain plug and subframe.

5. Open the *tabbed* radiator cap on the Filler Tank. It is located just above the engine. Removing this cap will help the coolant drain more quickly once the drain plug is loosened. Check that the cap has a rubber gasket under the cap lip and near the tip.

6. Loosen the drain plug (turning counterclockwise / lefty-loosey on the 07 STI) to allow the coolant to drain. Turn the plug out about 5 to 6 turns to get a decent amount of flow. The plug can be difficult to turn by hand and it is located in an awkward position. A small pair of pliers can assist you to turn it from underneath the car. If you have a lot of difficulty turning it, take a 14, 15, or 16mm standard socket to a machine shop and have a buddy grind out a 1/8" to 1/4" slot in it that is 1/2" deep. Remove the air intake scoop and if your arms are skinny enough, you can reach to the bottom of the radiator and make small turns on the drain plug. The engine coolant runs out very slowly and can take 30 minutes or more to finish draining. Please note that after the draining is finished, try opening the drain plug 1 or 2 more turns to see if there is an increase in flow. If so, let it drain for longer. I've attached a picture of the draining process to illustrate why you would want a wide container. I also tried running tubes. Do yourself a favor and buy a wide drain container. You can do steps 7, 8, & 9 while the coolant drains.

7. Pull the small rubber line completely out of the Reservoir Tank. Nothing holds it inside the tank. If there is coolant in the tube, allow it to slowly pour out into the Reservoir Tank to avoid spilling it.

8. Remove the Reservoir Tank, empty it, and rinse it out with Distilled Water. There is a plastic clip that holds it in on the right hand side. Push this clip back with your finger (thumb location in the picture) and insert a thin tipped flat headed screw driver behind the white plastic . Twist the screwdriver to gently pry the tank free. When you pull the tank out, note the location of the "Full" line.

9. Reinstall the Reservoir Tank. Make sure that the knob at the bottom of the tank seats in the bracket hole it was removed from. Also, make sure that the top plastic clip holds it in place. Reinstall the rubber tubing through the hole at the top. The tubing should be pushed towards the bottom of the Reservoir Tank.

10. Tighten the drain plug and wipe the area clean.

11. Reinstall the Under Cover. Put the 4 Push Pins in place first. There are 2 recessed tabs located just behind the 3 bolt locations at the front. To bolt the Undercover back to the car, you need to make sure the tabs in these 2 recesses are pushed over top of the metal shelf under the car. I used the back of my ratchet to pry them into position. If you don't do this, the Undercover will hang low and not allow you to reinstall the front middle bolt as there will be a 1" gap between the Undercover and threaded bolt hole. Reinstall the 3 front bolts and the 2 rear bolts.

12. Reinstall the Front Wheels by hand tightening the lugnuts in a star pattern. Make sure there is no slop by trying to wiggle the wheel.

13. Lower the vehicle off of the jack stands.

14. Tighten the Front Wheel lugnuts to the proper torque specifications. Always tighten in a star pattern.

***If you removed the air intake scoop, make sure you put it back before running the vehicle.***

Your STI Engine does not have any Coolant in it now for all practical purposes. Do not go on a joy ride as your engine will immediately overheat and make some nasty noises before it makes 1 loud and expensive clank.

Fill Procedure:

1. Place a funnel in the Filler Tank where the *tabbed* cap was removed.

2. Slowly add a 50/50 mix of Engine Coolant and Distilled Water to the Filler Tank through the funnel. Adding too quickly can force air into the system which will make the whole process take a little longer. We have to burp the air out of the system later. (If you have the 50/50 premixed solution, get to pouring. If you have the undiluted solution of Engine Coolant, mix it 50/50 with Distilled Water before adding it. Double check your bottles as it is easy for the Subaru dealership to accidently sell you one of each.) When the fluid starts backing out of the funnel, stop pouring and allow the fluid level to drop slightly into the Filler Neck. Note: Your Service Manual (not the Owner's Manual) will have a chart for different mixtures of coolant. If you want to run a more diluted solution, do so at your own risk. 50/50 will keep your coolant from freezing anywhere but the arctic circle.

3. Shake the Engine Coolant "Conditioner" well and pour some into the Filler Neck of the Filler Tank. Do not worry about pouring it all in the first time. You will get several chances to pour the rest in. Do not worry if it looks like shark chum with bits of chalk thrown in. These are all items that will dissolve in the system. Picture to be added soon.

4. Reinstall the *tabbed* radiator cap. It should screw on and stop. Double check that it is tight.

5. Remove the yellow cap on the Reservoir Tank and add Engine Coolant up to the "Full" line which is located halfway down inside the tank. Do not fill the Reservoir Tank to the top. Close the yellow cap.

6. Start the car and monitor the coolant temperature from the driver's seat (The picture below shows an 07 STI's normal operating temperature). By idling the car, you are allowing the car's engine to heat up. There is a thermostat that will kick the cooling system on and pull the engine coolant away from the Filler Tank and Reservoir Tank you just filled. You will know that the system is on when the Radiator fans kick on. Let the car run for a few seconds after the fans turn on and then turn it off. Make sure to turn the engine off before the needle gets above the 2nd mark on the Temperature Gauge in the dash. If it goes much higher, it can cause the engine to overheat which would be bad. ***Warning: If you are in a garage, make sure that the garage door is open to allow the Carbon Monoxide fumes to vent out.***

7. With the engine turned off, let the car cool off for at least 10 minutes to allow the radiator system to lose some pressure and heat. I recommend waiting 20 minutes the first time and reduce that time as you gain some comfort level with what you are doing.

8. Remove the *tabbed* radiator cap, but be careful. If you feel hot vapor or pressure when removing it, let it sit for a few more minutes and then remove it. Part of the reason you are wearing safety glasses, gloves, and a long sleeve shirt is so that a release of hot vapor will be less likely to burn you if you did not let the system cool long enough. When you finally remove the cap, you will hear some gurgling noises because air is trying to exit the system at the Filler Tank while Engine Coolant is trying to make its way to the bottom of the Engine and Radiator. This is referred to as burping the system or bleeding the air out.

9. Slowly add more of the Engine Coolant to the Filler Tank just like before. Also add the Engine Coolant Conditioner to the Filler Neck once the Filler Tank is full. You will also need to refill the Reservoir Tank to the "Full" line with Engine Coolant. These levels have dropped since the fans kicked on. Replace all of the caps and make sure they are tight.

10. Turn the car engine on just like before and run it again. Monitor the temperature gauge on the dash. In a nutshell, you repeat this process over and over until the fluid levels no longer drop (It took me 10 times). As more and more engine coolant enters the system, idling the engine will not be sufficient to raise the temperature high enough to kick the radiator system on. At this point you will need to start revving the engine between 2,000 to 3,000 rpm to get the radiator fans to cut on. You should also operate the heater at the maximum hot position while having the fan set to the low position. Let off the gas pedal often to check if the radiator fans have turned on. Once they have turned on, let the car idle for just a bit. Remember to turn the engine off before you go above the 2nd mark on the temperature gauge in the dash since you do not want to overheat the engine.

Additional Note: You may find that you can't put as much coolant back in as you took out. The last time that I changed the engine coolant, I would have to check the Reservoir Tank each morning before driving to work. Here, I was able to add additional coolant each morning after the car had cooled over night. After a few mornings, the Reservoir Tank level will stop dropping.

That's all I've got for now. I'll update somewhat based on feedback. Good Luck!!!

Update 1: You can speed up the filling/burping process by filling up the radiator first. Put the cap back in place and do not remove it again since it is not the highest point in the system.

Update 2: Some users recommend running the engine while continuously pouring coolant into the filler tank until it overflows. This method is fast, but you run the risk of overheating the engine if you aren't monitoring the coolant temperature. Engine coolant can also catch on fire if it spills onto any part of the engine exhaust.

Update 3: Commercial flushing systems can be detrimental to your cooling system. They often use chemicals that can react with the coolant and deteriate the aluminum. You also run the risk that they can damage the thermostat if they are not careful. If you want to flush your system, the safest option is to fill it with distilled water, run it, and drain it again. The more times you refill and drain it, the better the flush.

Update 4:
I'm in process of studying to change my timing belt and ran across these youtube videos. Some of you may have posted about these videos already in the threads following. In any case, the videos contain helpful information and ideas on changing your engine coolant. "Meaty's" procedure is a little different than mine, and it is probably more efficient if you know what you are doing. My method is more in line with the service manual, but slower. I recommend following my method until you know what you are doing. Videos 1, 4, and 5 contain the information.

Video 1: (5:27 to 8:25) Meatys Subaru Timing Belt Guide (HD)(1/5) - YouTube
Video 4: (6:08 to 15:00) Meatys Subaru Timing Belt Guide (HD)(4/5) - YouTube
Video 5: (0:00 to 1:55) Meatys Subaru Timing Belt Guide (HD)(5/5) - YouTube

 

Drain Procedure:

10. Turn the car engine on just like before and run it again. Monitor the temperature gauge on the dash. In a nutshell, you repeat this process over and over until the fluid levels no longer drop (It took me 10 times).

I guess I didn't read this part the first time and thought something was wrong with my car. Thanks for the great write-up!!

 

Finish quick! I wanna do this on my 04! Thanks in advance for making this

 

Great write-up so far. Can't wait to see the final edition :tup:

 

Thanks guys. The first iteration is ready. Take a look and let me know if you encounter any problems. Let us know if there are alternative methods. I know of a few, but it'd be better for someone to comment that has actually performed those methods.

 

this is a very good write-up!

Here's a picture of the subaru coolant, you can add it to the DIY it wont go anywhere from my server
http://members.brimd.com/sujak/STi/SubaruCoolingSysCond.jpg

You can buy it from your local dealership for about $3 (Subarugenuineparts.com doesn't have it )

Make sure you SHAKE WELL before you pour it in

 

Nice write up, I actually had to use a pump to empty out my reservoir and just used some distilled water to clean it out, pumped out the water.

-Gio

 

Nice write up, I actually had to use a pump to empty out my reservoir and just used some distilled water to clean it out, pumped out the water.

-Gio

What type of pump did you use and what were the connections?

 

Good work...so complete :tup:

 

Thanks sujak...will do.

 

So what are "normal" coolant operating temperatures? You can monitor using the Cobb APv2 right?

 

So what are "normal" coolant operating temperatures? You can monitor using the Cobb APv2 right?

I popped my AP on to test this since you asked. It read my operating coolant temperature (07 STI) at 188 to 190 degrees F after going WOT on an on-ramp. I would still monitor the system by the needle gauge on the dash when performing the coolant change as an added safety measure.

Here is what my Service Manual (07) reads from the General Section on the Coolant System concerning Temperature.

"The engine cooling system consists of a down-flow radiator which features high heat-dissipation performance, an electric-motor-driven fan, a water pump, a thermostat, and an engine coolant temperature sensor. The ECM controls the operation of the radiator main fan and sub fan depending on the signals from the engine coolant temperature sensor, vehicle speed sensor, and A/C switch."

There is a chart in the Service Manual (07) that says the radiator fans will turn on high speed if the Coolant Temperature reads 203-207 degrees F. That should give you an indicator of when the system will definitely cut on if it hasn't already. If you turn your A/C on, it will turn on much sooner (196-201 degrees F). The reason I've given a temperature range is that the Service Manual chart has more detail than can be described in a few sentences. I've left this portion out of the write-up as it's more technical than necessary to perform the service. It's still good to know that you can check it with the AP.

 

One of the best write ups i've seen. :tup:

 

Do the tires really have to come off to change the coolant?

 

You can do it with the wheels in place, but it helps a lot with access to have at least the passenger side front wheel removed. I went ahead and removed both for easier access with the Undercover as well. The drain plug doesn't turn very easily sometimes so it helps to have room to move around and see what you are doing. If I had a lift like a dealership or mechanic shop, I wouldn't bother with the wheels.

If you try it, let me know how it works out.

 

Great write up, very detailed. A+

Add to sticky "How-To" catalog? here? http://www.iwsti.com/forums/how-install/63506-howto-catalog.html

 

Great write-up.

I'm having a problem understanding the dillution process. Blame it on my bad engrish

I have bought the conditionner and 1 undiluted coolant. You are saying I have to buy another undiluted coolant and poor both container in one big container and then add water?

 

Hi Rennes,

Your coolant system holds about 7.7 liters. It is recommended that you put 1/2 distilled water (3.85 liters) and 1/2 undiluted coolant (3.85 liters) into the coolant system.

The undiluted coolant bottle you bought is 3.75 liters and is 100% coolant without any distilled water mixed in. You need to find a way to mix it with 3.75 liters of distilled water and then pour the mixture into your coolant system.

I recommend buying a 50/50 premixed solution bottle in addition to the undiluted coolant you bought. Your Subaru dealership should have both on hand. If you have the 50/50 premixed solution, you can pour it in first. Then you will have an empty coolant bottle to pour half of the 100% undiluted coolant into. You can check that the bottles are at half by holding them side by side in the light or looking down through the cap. Once you have the levels equal, fill both bottles near to the top with distilled water. Put the cap back in place and shake. You now have 2 more bottles of 50/50 premixed solution.

Does this help? Someone else might have another suggestion on how to do this.

 

That's perfect, thanks STI Sibb

 

excellent write-up.

 

best write-up ever!!

 

I was unable to get all 8.1 quarts of coolant into the system. Is the reservoir tank included in the 8.1 quart coolant system total? The car seems to be running fine and the temperature ranges from 180º-185º F while driving and up to 196º F idling at a stoplight for over a minute.

This was an excellent write up! Thanks for taking the time.

 

Nevermind.... wouldn't ya know it I just read the manual and the coolant total does include the reservoir....

 

Have you used any other coolant products such as MoCool?

 

I personally haven't as this is the first time I've changed my coolant. If you do a search, this topic is probably covered somewhere else in the forums. If not, start a thread and you'll get plenty of response.

 

I followed this to the T, but was only able to get about 7 quarts of fluid out. About the same went back in. It looks like a quart was trapped in there somewhere. I let it drain for about 45 minutes. I backed out the drain plug at least 6 turns.

Any ideas. I'm guessing there was some fluid in the hoses...

 

I followed this to the T, but was only able to get about 7 quarts of fluid out. About the same went back in. It looks like a quart was trapped in there somewhere. I let it drain for about 45 minutes. I backed out the drain plug at least 6 turns.

Any ideas. I'm guessing there was some fluid in the hoses...

There will always be some residual in the system, but did you count the amount of coolant in the Reservoir Tank? The Reservoir Tank doesn't drain. You have to pull it out and empty it.

When you say 7 quarts, do you mean 7 liters?

 

hey, I was told that it's a good idea to flush your radiator before filling it up with coolant with distilled water (fill the system up with only distilled water and let the car warm up to flush). Also, I heard that to burp the coolant after the fill, you can just start the car with the radiator cap off and let the engine heat up, and burp the system. I believe that this will save people some time.

Anyone else tried these methods?

 

Also, I heard that to burp the coolant after the fill, you can just start the car with the radiator cap off and let the engine heat up, and burp the system.

i followed these instructions perfectly.
after i finished draining and plugging it back up i filled then started the car with the rad cap off and warmed the car up a bit and "burped this system".

I've seen a few other members mention starting the car with the cap off of the fill tank to burp the system. Where are you guys getting this info from? I'm not an expert but that doesn't sound like a good idea and it's not the method listed in this 'how-to' or in the service manual.

Does anyone know if the Subaru dealership just follows the steps listed in the service manual for a coolant change, or do they actually use one of those machines to flush the old fluid out?

 

flushing that way shouldn't hurt anything, but if your coolant looks fairly clean when you drain it, there should be no need. that seems like a lot of extra work. i actually bought enough distilled water to do that, but when i got to the point of refilling everything later in the day, and was burping it, i decided to just set the water aside for my IC spray.

 

I want to to do my coolant this weekend but mix in some Water Wetter. Does anyone know what ratio I should use of water, coolant and water wetter for a daily driver and once a month track day?

 

if you never see any freezing temps in your area, i'd reconsider whether to use any anti-freeze. just water, wetter, and conditioner may be enough for you. in AZ, you certainly don't need a 50/50 mix. i don't know the ratio of wetter to use, but i'd hope they'd have the answer on the bottle.

 

They have suggestions on the bottle. It can drop into the 30's at night during the winter in Phoenix. Nothing too cold though.

 

is it better to flush out the coolant system with water or w/e before doing this?

 

It's not necessary, but all it requires is your time and a gallon or 2 of distilled water if you want to flush any remaining particulate out of the system.

Some people will refill the system with distilled water, run it, then drain it as a cheap and safe way to flush before adding the coolant mix. There are other methods out there as well, but none of them are necessary for "changing the engine coolant" as prescribed in your owner's manual. As with the coolant filling procedure, be mindful of the temperature gauge. It takes several cycles to remove all of the air from the system.