legacycentral bbs

well it happend agian, its a koyo rad and it broke in the same spot as the last one i had what is this problem?

i got the rads at the same time! also its two total diffrent motors i used.

my dads answer to much boost!!

so this is the motor ej20g dohc heads and ej22t block with 16g evoIII running 20psi, rad is leaking on drivers side front top "fin bar"

old motor i broke brand new rad koyo as well, ej20k dohc ej22tblock wiseco pistons and aps sr56 running 20psi, broke in the same spot!!

is it cometic head gaskets? is it not having arp head studs? is it the rads where both orderd the same time and they are both no good?

the most funny part about this is, if you guys remmber how i put the last rad in the car i was sure it messed its self up becuse of the way it sat. i take it! it was ok!! and i didnt even need to make the rad sit perfect like stock.

old rad set up that i was sure it broke it i guess not and this borke like the other one same spot!!!



this is how i made the rad sit bye makeing a hole new support and it even use the factory rubbers to hold it in place like it came stock.



brand new out the box, shit i would say 3 - 4 months now of abuse and it leaks same spot? what gives.


back side spray



am i loseing it or did i happen to get two shit rads becuse i order them the same time and becuse it has to happen to me?

I'd contact Koyo. If you're getting enough boost leakage into the cooling system, you'd blow the weakest point first. That point should not be the weld on the radiator. I wonder what pressure they test their radiators to. Maybe it was made by some trainee on the same day.

I would think the hose would fail before the radiator unless your coolant is acidic from too much exhaust. My heater core leaked because of acidic coolant once

thats what i was think as well guys!! it should not blow the rad i was thinking the rubber hose would have blown apart.

i dont know!! but i am sure going to freak out and get two new rads from my supplier. only i brake things like this, if i would have had a subaru rad it would have last me a million years. its like everytime i order something after market i seem to brake it.

Exploding Radiators is a sign of a HG leak.

Maybe when you push the boost to 20psi one of the HGs starts leaking cyl pressure into the coolant system.
Cyl Pressure is alot more than 20psi which is about what a 1.3bar (19psi) rad cap would run a coolant system @ normally.

Did you repair the first rad or throw it out?
The seam would be the easiest place to make a repair.

My Koyo is doing the exact same thing, after owning it for a hair less than one year. Needless to say I'm not happy. It's not the weld right there, it's weeping from where the tubes are braised into the endtank.

My headgasket isn't leaking. I never get bubbles coming into the overflow. The car never overheats. I'm not using any coolant other than the little bit that is weeping out of where the core tubes go into the endtank.

I spent 40 minutes on the phone with someone at Koyo USA and the long and short of it was that I was basically told to get fucked.

We need to start a campaign. I'm going to send them pics of mine and yours when mine comes out. My replacement (same thing) should be here soon. I'm crossing my fingers on the next one.

If they still don't want to do anything, I'm going to slander their name across the internet and elsewhere to the best of my ability.

In Nico's case, the theory is that the HG would be leaking only under really high boost pressures, though I can't see that helping their longevity, I suppose he goes through engines so fast it doesn't really matter. That said, I still think the pressure should blow something other than the radiator first or at least show signs of damage elsewhere.

If boost pressure is high enough to do that, wouldn't that also adversely affect lubrication? I would imagine you'd see some sign of coolant in the oil, perhaps frothing, perhaps the oil pressure light would come on (might be a good idea to hook up a real pressure gauge that records peak pressure to either the oil or coolant and see what happens. Coolant makes more sense).

Any oil in the coolant?

Aren't there other good aftermarket options??

yeah obvisously not koyo

evolutionmovement wrote:In Nico's case, the theory is that the HG would be leaking only under really high boost pressures, though I can't see that helping their longevity, I suppose he goes through engines so fast it doesn't really matter. That said, I still think the pressure should blow something other than the radiator first or at least show signs of damage elsewhere.

If boost pressure is high enough to do that, wouldn't that also adversely affect lubrication? I would imagine you'd see some sign of coolant in the oil, perhaps frothing, perhaps the oil pressure light would come on (might be a good idea to hook up a real pressure gauge that records peak pressure to either the oil or coolant and see what happens. Coolant makes more sense).

Any oil in the coolant?

There is no oil visibly in the coolant. I have not had it checked for hydrocarbons yet, but the thing never gets hot even when I beat the car like it owes me money.


I run about 21psi out of a GT2871R at the moment limited by my injectors. When it was cold out I had it up to about 27psi. My buddy was running that much boost out of a GT3076R with the 22T headgaskets, and didn't have an issue until he lost a wastegate hose and spiked to over 40psi. Even then, it was a tiny little leak. It showed up as rising coolant temp when he got on it. I have no such issues. I have a real temp gauge too, not the joke of a factory temp gauge.

My friend is using a factory style radiator and with the leaking headgasket, it would just bubble out the overflow. You could hear it boiling in the motor and the radiator didn't complain at all.

I'm pissed that mine is doing what NICO's is and this is his second one that is doing the same exact thing.

LOL - I have not beat a car liked it owed my money in a long time.....

I have a KOYO too - I bought it figuring it did not have plastic end-tanks that would crack & leak but I did not know there was a problem with these things leaking.
The one on my OBS-t has worked well for 2 years now.

All of the Blown Subaru HGs I've seen did not mix coolant & oil, the cars would just fill the overflow bottle up & then overheat.

I thought Nico's car was leaking only @ high (ish) boost- so it would not have the normal symtoms, but now that I hear a few folks have had the same problem in the same location I'd say it may well be a problem with the rad.

Well, I have the same radiator on the way, and I hope it lasts for a while. The leak is not the end of the world though. In a month my overflow tank has dropped about an inch, so its not like the coolant is pouring out.

Ya Derek's car didn't have oil in the coolant either. He would have temps come up under load, and then blow out the overflow. He got his coolant tested for hydrocarbons which confirmed the leaking headgasket.




NICO, do you have pics of the first radiator leaking? I'm going to put together a nice little email to KOYORAD.

Same here with observed bad HGs - they only seem to collect combustion gases, eventually causing water pump cavitation. But in a high-boost scenario temporarily causing the issue, I think the excess pressure would show some signs beyond the radiator cracking. If that is the cause, it still doesn't speak well for Koyo that the radiator pops before the cap, hose, whatever. Either way, I see it as a poor product. Guess that's why they sell relatively cheap.

They are supposed to be from their best line, being the R-core. I figured the R1819 was less expensive since the demand isn't there unlike the demand for the newer style of Subaru radiator.


I wonder if a competant radiator shop could fix it. Re-braise it or whatever they do, and at what cost. The coporate guy I talked to said people have tried with very limited success. But he was a dickbag, so whatever.

I bet a good Rad place could fix it.

My buddy regularly chops & reconfigures the end-tanks of Radiators (which usually includes welding in BIG AN fittings & "making" the rad fit the car it will be used in) & welds them back up when hes done (Aluminum-Tig).

When the tanks are off all of the tubes are visible & can be played with if needed.

Anyone want to sell me their broken Koyo radiator?

Are you handy at braising?

NICO, how long ago did buy those two radiators? I'm trying to figure out if they were around the same time that we got them. I bought mine in June of last year.

holy shit i am not the only one!!

ok let me see.

my car never over heats, my car runs perfect, it has never over flowed rad fluid once, it is all in working order.

this is with 2 set up diffrent motors now.

i got the rads at the same time, on the box it siad march 12 2007 but i got them lets say october 2007 if i am right, my motors blow up just around winter time.

i have lots of pics, but today i sent my first rad to JRP where i am from and they are going to look into it, they dont belive it as well!! both the things broke in the same spot.

93forestpearl i cant type as good as you, but ill give you what ever pics you need, i want new rads or money back so i can go bye a factory subaru rad becuse i no dam for sure they wont break(after 14years).

things this thread has tought me:

keep the stock radiator.

if it ever breaks, buy another stock radiator.

Stock NA radiator good for 26 psi/400whp....

But only 1.4 mile at a time. haha

douglas vincent wrote:Stock NA radiator good for 26 psi/400whp....

But only 1.4 mile at a time. haha

LOL hahaha.


greg donovan you can say that agian!!!!


shit over the years all the aftermarket stuff brakes even thow its "1million times race better they say" and my factory subaru stuff holds up like i am rallying my car 24 seven for 14 years.


the funny thing about this broken koyo rad is, i drive the car hard to see if it makes it leak and it dont leak all the time. its got to be a shit job makeing these things!!!

i have another question for everyone!!

how come on most of the legacy models that use the rad that goes cross flow? end tanks left right?

but if you look at a impreza and sti they have to top bottom, and they use 2 rad caps?

is this becuse it lets out the pressure when the shit hits the fan? should i be useing say like the sti ver one?

my dad says legacys are better becuse left to right style, but i just dont get the up down thing subaru did and there 2 rad caps one on rad and other on the top tank if its called that.




ps i cant wiat for california koyo to open so i can FREAK out on them becuse another person with same rad in a diffrent country miles away from me has the same dam problem.

change the title of the thread also so pepole will be aware of this

Ohhhhh, shit. That's about the same time I bought mine, as well. And I've been losing coolant, and can't find a leak in any of the hoses.

Where are you guys sourcing your radiators?

I bought it from Raceinspired.com, and I have another on the way from them. I am kinda stuck since my setup is built around that radiator. Also, last summer when I need it, it was only $40 more than a factory style radiator. OEM Subaru radiators are no longer availible.





In the next few days when I get my radiator out I'll take pics and we can go from there. Mine looks exactly like yours does.