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Old 02-07-08, 09:42 PM   #1
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Default Install aftermarket radiator (Koyo racing rad), and flush the coolant

I ordered the Koyo Racing Radiator a couple weeks ago and it arrived yesterday afternoon. Today was install day.

I took a bunch of pictures during the install so I figured I'd post a How-To for those wanting to upgrade their stock radiator to a better cooling, higher performance radiator for big turbo setups.

This isn't the end-all-be-all of radiator installs, so don't read it as bible - I probably screwed up here and there, and there are likely better ways of doing things, so be warned.

-----------------------
Koyo Racing Radiator - part number R2704




Step 1 -
Get front of the car in the air.

Step 2 -
Remove undertray - a few bolts and a few snap clips

Step 3 -
Remove your radiator cooling panel (if you have one) and/or remove the two metal brakets that attach at the top of the radiator.




Step 4 -
Remove both radiator caps - the cap on the radiator itself, and the reservoir cap.




...hate winter... look at the grime under the cap:


Step 5 -


Drain the coolant (obviously have something to catch the coolant as it drains):
  • There are two methods of doing this:
    • 1) Unscrew the pet**** valve and drain from the lower passenger side of the radiator (picture looking from passenger side, looking straight down on radiator), or;
    • 2) Remove the lower driver side radiator hose and be ready for the wild coolant rapids to come thundering out (sorry, not the best pic - looking up from the underneath the car on the driver side)
- one thing to note is that when doing the pet**** drain method, ideally you'd have a hose of some sort to keep things clean. In my case, , I let the coolant drain over the subframe and into the basin I had waiting. It made for a smoky first start up.

Step 6 -
Now that the radiator is drained of coolant, time to get it ready for removal.
- Remove all coolant lines going into and out of radiator (not all shown in pics):






Step 7 -
Unclip wiring harnesses for radiator fans, one on each side of the rad.




Step 8 -
Remove radiator. This is simple enough but will require a lot of wiggling, pushing, pulling, and finessing to get it out. Having the battery out as well as the coolant overflow tank would help, but I didn't need to.


OEM radiator out:


OEM vs Koyo (bigger and thicker ):




Step 9 -
Transfer rad fans to new radiator. I used the OEM bolts - some people encourage buying new M6 (IIRC) 15mm bolts instead of reusing the stock bolts since they're like sheet metal screws. I was fine using them and everything went smoothly.
OEM setup:


Transfer to Koyo:


Step 10 -
Install Koyo. Pretty much the opposite of removal. It's a lot thicker than stock so it makes clearance a bit tighter and getting in a bit more difficult too. I had to cut off a few plastic pieces that jutted out of the OEM fans since they were in the way of either the coolant overflow tank or the pulleys and motor.


Clearance between rad and pulleys:


Step 11 -
Re-install all coolant lines and hoses as they were setup originally.


Step 12 -
Add coolant mix back into the rad. I followed the [50:50 Subaru coolant: distilled water] mix plus the Subaru coolant additive since I'm in full on winter. I need the antifreeze .
- Leave both radiator caps off.
- Pour coolant mix slowly into radiator slowing using a funnel (the slower you go, less air bubbles from bubbling).
- While doing this, squeeze the top radiator hose which will also burp the system a bit while pouring.
- When the radiator is full (the Koyo took about 7L+), fill the coolant reservoir.

Step 13 -
Burp the system. With the caps off, start the car.
- The coolant will bubble and "burp" and foam which is what you want since the air is being purged from the system.
- Revving the motor to 2k was also recommended from the Subaru service manual and forum threads.

Step 14 -
Once the system is burped, add coolant to the radiator and the reservoir so that they're both full.

Step 15 -
Reinstall upper radiator supports, radiator cooling panel, and enjoy the 20-30% higher cooling factor of your new racing radiator

Issues I had:
1) The mess. I really should have had a hose of some sort attached to the drain valve so the coolant would drain through there and not all over the subframe. Sadness.

2) Radiator fan rubbing OEM top rad hose. I reused the OEM hoses even though they will ended up being a bit too long. They are completely fine uncut though, so buying new rad hoses is definitely NOT a necessity.

Anyway, on first start up, when the rad fans finally kicked in, I thought my motor seized. The sound was like a thousand cats screeching hells fury. It was actually just the passenger side radiator fan that was jammed against the OEM top rad hose since 1) the new rad is thicker so there's less clearance and; 2) the OEM hose is too long.

With some adjusting and the use of a zip tie or two , everything is perfect.

Performance:
It's 0*F here... I don't think I can give a fair opinion of the increased performance in this kind of weather. I'll know more when it's strapped to a dyno.

Let me know if and where I screwed up, and I'll adjust the instructions.

Cheers!
TLP


Last edited by Wes; 11-08-08 at 10:11 AM.
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Old 02-07-08, 09:57 PM   #2
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

Very nice write up. You make it sound easy
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Old 02-07-08, 10:14 PM   #3
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

^Wasn't too bad. First time through always sucks... second time through would be cake
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Old 02-07-08, 10:29 PM   #4
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

matt you need to get some better looking samco hoses!!!
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Old 02-07-08, 10:40 PM   #5
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

^+1 ...and new hose clamps.
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Old 02-07-08, 11:09 PM   #6
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

Great write up. ALways good when there are no leaks to be found after your done.

One thing though for everyone that does not own an 06-07 vehicle. When installing a new radiator. I would suggest flushing the system to get the old radiator fluid out before putting new in. Of course this depends on how long it has been since you flushed your system last. Since this is an 07 he didn't need to do it although it is advised but not needed. If your car older then an 06 and never had a radiator flush I would definately advise to do so before putting new fluid in the car.

How to do this you say. There are many ways to do it. One is having a shop do it not adviseable since you are changing out the rad anyway. Just take the hoses off the old rad after you drained it. Place a water hose in the top rad hose an turn it on. Let the car idle for aprox 2-5 minutes. There should be no more old anitfreeze in the system.
Plug the hoses with a clean rag. And get out the handy dandy air hose with a blow nozzle and blow everything dry. Or close to it. Clean up your work station and Your free to continue the install.

As for the flush water you can put it into a 5 gallon bucket and poor it into milk jugs later on. Since all antifreeze is bio degradeable now adays it's not a huge problem for the ground. I usualy catch the first two gallons and let the rest run off. Thanks Jeff

Last edited by Arfrce; 02-07-08 at 11:13 PM.
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Old 02-07-08, 11:36 PM   #7
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

nice, did you shop around for a better price? If so shed some light.
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Old 02-08-08, 05:11 AM   #8
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

Awesome job Matt....I will def read this out when I do mine. Any more pics of the "cutting" you had to do to make it fit? Thanks for a great writeup, it looks mad easy, just time consuming, how long did it take you?
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Old 02-08-08, 05:22 AM   #9
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

i always wondered if this was a worthwhile mod... im interested to see your findings
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Old 02-08-08, 08:50 AM   #10
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Default Re: How To: Install aftermarket radiator (Koyo racing rad), and flush the coolant

Quote:
Originally Posted by blindfold View Post
nice, did you shop around for a better price? If so shed some light.
Was that directed at me? I assume you're asking where I got the Koyo? eBay: KOYO 53mm RADIATOR 03-07 Subaru Impreza WRX/STi R2704 - (eBay.ca item 280192738959 end time 14-Feb-08 21:19:20 EST)
You want the R2704 - that's the upgraded rad (not the OEM replacement).

That's $100 cheaper than anywhere I found on IWSTI or NASIOC.

Quote:
Originally Posted by Arfrce View Post
Great write up. ALways good when there are no leaks to be found after your done.

One thing though for everyone that does not own an 06-07 vehicle. When installing a new radiator. I would suggest flushing the system to get the old radiator fluid out before putting new in. Of course this depends on how long it has been since you flushed your system last. Since this is an 07 he didn't need to do it although it is advised but not needed. If your car older then an 06 and never had a radiator flush I would definately advise to do so before putting new fluid in the car.

How to do this you say. There are many ways to do it. One is having a shop do it not adviseable since you are changing out the rad anyway. Just take the hoses off the old rad after you drained it. Place a water hose in the top rad hose an turn it on. Let the car idle for aprox 2-5 minutes. There should be no more old anitfreeze in the system.
Plug the hoses with a clean rag. And get out the handy dandy air hose with a blow nozzle and blow everything dry. Or close to it. Clean up your work station and Your free to continue the install.

As for the flush water you can put it into a 5 gallon bucket and poor it into milk jugs later on. Since all antifreeze is bio degradeable now adays it's not a huge problem for the ground. I usualy catch the first two gallons and let the rest run off. Thanks Jeff
Good call Jeff - I didn't need to do a full flush simply because I already had my coolant fully flushed last summer (major install) so I was already on new'ish coolant.

Very good point though - I'll add it to the How-To.

Quote:
Originally Posted by Chris05STi View Post
Awesome job Matt....I will def read this out when I do mine. Any more pics of the "cutting" you had to do to make it fit? Thanks for a great writeup, it looks mad easy, just time consuming, how long did it take you?
Thanks Chris. It is super easy... just irritating trying to fit the bigger core. Test fit, see what's in the way, cut or adjust, test fit again... etc etc.

The only cutting I needed to do was here:


Just cut those tabs off (the lower middle one will interfere with your headers), and you're good to go.

Quote:
Originally Posted by chaos311clarity View Post
i always wondered if this was a worthwhile mod... im interested to see your findings
It definitely is... for big turbo setups that will see a lot of track time. And it seems that the '07s are in need of a better radiator for added cooling from what I've read.
Anyway, this is more preparation for my big turbo and longblock build, so I figured I'd do everything possible to make it as safe as can be.
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