I did mine last Jan. at <90K mi. due to OEM leaking at caps - I'd say the Koyo racing rad is maybe a bit heavier, being thicker and all metal, plus even if it was lighter, it holds about a half gallon MORE coolant than stock. So, it's no weight saver...

unless you count the bit o' hose you cut off in the equation.

 

my friend with 07 WRX just called me and said that his radiator just blew up too..

 

Tis the season. Hope he did not overheat too.

 

The only issues I've had with cooling was when the coolant wasn't properly burped. It took a few times of burping it to make sure all the bubbles were out of the system. Once all the bubbles were out of the system though as soon as it gets up to Operating Temperature I have not had any issues. No matter hot or cold, hard or easy driving I haven't seen any issues with the temperature as it has remained a consistent temperature.

The Temp Gauge in your car has probably 4 hash marks on it. Cold, Just Under Half (probably about 40% up the gauge or so), Just Over Half (probably about 60% up the gauge or so) & Hot. When my car gets up to temperature it is above the 40% mark, but lower than Half Way (closer to the 40% mark rather than the 50%). This is using the Subaru Blue Coolant.

 

how big was the crack on yours? cuz you said it just started to steam but not over heat, yeah?

 

BTW, you can do the 160 Degree Thermostat like the Grimmspeed.

Grimmspeed Subaru 160 degree Thermostat - Modern Automotive Performance

or if you feel more safe going with the OEM Temperature Range 170 Degree you have options like the Fast Motorsports Thermostat.

Fast Motorsports 170 Degree Failsafe Thermostat (Subaru) - Modern Automotive Performance

or the Gimmick Motorsports one to name a few.

Gimmick Motorsports Thermostat - Cooling - SubaruWRXparts.com



This particular one though (if it really is a 140 Degree Thermostat) I would completely avoid as that seems Far Too Low of a Temperature to allow your car to run properly.

OAKOS Automotive - STi & WRX Performance Parts: Mishimoto 140F Thermostat, WRX & STi

 

I have a crucial one laying around that Im not using if you wanna grab it. I tested it to see if it was working because I was bored one day, thermostat opens up and everything.

 

Use a factory Subaru thermostat for reliability purposes.

 

Yes. A Koyo that holds nearly twice as much coolant is already going to be a bear to warm up on a DD. My car is stone cold after a couple hours and it gets pretty annoying. If I did it again I would stick with a stock type on any sort of a DD. IMO unless you race the OEM cooling system is plenty capable, and the engine heat up quick enough to avoid any inconvenience.

If you don't warm your car up, then disregard...and start saving for an engine build

 

You won't be disappointed with the koyo. It's a nice piece.

 

I did not do that close of an inspection but it looked to be about an inch or two. Yes it definatly did not overheat I had it off the freeway a couple seconds after I saw a small wisp of steam.

 

Kevin got back from his vacation and got the radiator done for me. He said he tried burping the system for like two hours and could not get the bubbles to stop bubbling. He said it could be the headgasket.

Kinda puts a damper on driving to Portland tomorrow.

 

damn dude that sucks! hope you can figure something out. take the alltrac?

 

The alltrac handles like doodoo. It needs all the bushings replaced and the shocks are blown. I don't know why but that thing grabs EVERY rut on the highway so you have to pay serious attention.

After playing with it a few more hours, Kevin gave me the OK to take the wrx. No oil in water or vice versa. Can't seem to burp the coolant completely.

 

Mine did that too.

I've been driving it for month and still no mixing fluids.