Why you shouldn't buy from koyo
Joined: Oct 2003
Posts: 1,600
Likes: 49
From: Norcal/Bay Area, CA
S5 has the extended neck and overflow on the driver's side. S4 has no neck and the cap is in the center. It is possible they put the wrong radiator in the box since everything seems to be wrong with the one you received.

The car is a 1989 s5, so unless the previous owner replaced the rad with a s4 rad then no, I don't have s4 brackets, I have s5. I will post pictures when I get home to show what I'm talking about. The main thing was it hit the hood when I got it bolted in, and would have hit my sway bar if I somehow lowered it any.
website may say one thing but a simple search here would have revealed that the airbox does not fit. So yes it bolts in, its a direct bolt in and it fits, just doesnt fit the airbox. Kind of a gray area the way its advertised
call a local radiator shop and see if they can get you a factory style replacement radiator
call a local radiator shop and see if they can get you a factory style replacement radiator
Joined: Aug 2008
Posts: 1,018
Likes: 3
From: Kansas City, MO

I think I figured out the problem.... The Previous owner put a S4 Radiator in place of the factory s5 one along with the brackets. Me in my stupidity didn't even think of that option. but from what you said, my cap is in the middle under the air vent. I wouldn't even think they would be interchangeable. I still am a little annoyed that I would have to change the air box setup. And they advertised that it was no modifications required. Thanks for you all for the help. My other complaints still stand though.
And I think that unless came true. Man I feel like a Jackass. I think the title of this thread should be changed to "Be Cautious about buying from koyo"
Time to change the title of your thread big guy....
Joined: Aug 2006
Posts: 889
Likes: 0
From: where the wild things roam
I dont think any of the thicker aluminum radiators are going to fit with the stock air box. Your going to have to either settle for a stock size replacement (which will still be better than a stock one) or plan on keeping the koyo and getting a free flow intake. Decent price stock size radiators can be found on ebay for relatively cheap around 150ish iirc.
Joined: Sep 2005
Posts: 25,581
Likes: 136
From: Smiths Falls.(near Ottawa!.Mapquest IT!)
Title: Don't buy a S5 Car with an S4 Rad,then BUY a KOYO.
Subject:
Koyo failed to warn me that the Rad they manufacture will not fit if I have a S4 Rad in an S5 Car..and use my S4 Brackets.
I am suing them for Misrepresentation and loss of wages.I will be on Judge Judy on
January 16/2014 to Plea my case.
I am looking for witnesses to help me establish the fact that the Typing in the Instructions is too small and too vague.Not only that,it is not Printed in Swahili.
I am also going to argue the fact that the Radiators just come in Chrome color and that is Color discrimination.All other colors are now jealous that they cannot become Koyo Radiators
.The latest testimony about this was when the Color BLACK said "say wut?,That's whack!"
Blue was too embarrassed to Talk.
Red was Fuming about this.
White was overheard sayin" Howard..uh..I think it won't fit..Maybe you should post a thread".
(posted in fun!Glad you solved it.)
Subject:
Koyo failed to warn me that the Rad they manufacture will not fit if I have a S4 Rad in an S5 Car..and use my S4 Brackets.
I am suing them for Misrepresentation and loss of wages.I will be on Judge Judy on
January 16/2014 to Plea my case.
I am looking for witnesses to help me establish the fact that the Typing in the Instructions is too small and too vague.Not only that,it is not Printed in Swahili.
I am also going to argue the fact that the Radiators just come in Chrome color and that is Color discrimination.All other colors are now jealous that they cannot become Koyo Radiators
.The latest testimony about this was when the Color BLACK said "say wut?,That's whack!"
Blue was too embarrassed to Talk.
Red was Fuming about this.
White was overheard sayin" Howard..uh..I think it won't fit..Maybe you should post a thread".
(posted in fun!Glad you solved it.)
Personally I don't like judge Judy, she is too easy. I plan on taking this onto jerry springer. That koyo rad actually pulled a knife on my car for being red. racist radiator...
Ya, I wish I could change the title to "Be aware of what you are buying and what you have in your car." Seroiusly if the mods want to they should change it to something along those lines.
Koyo is ok just thought it would work better in this case. I sent it back today, and I have the very last oem radiator that Mazda America has in stock (price was actually pretty good) coming in the next couple of days.
Ya, I wish I could change the title to "Be aware of what you are buying and what you have in your car." Seroiusly if the mods want to they should change it to something along those lines.
Koyo is ok just thought it would work better in this case. I sent it back today, and I have the very last oem radiator that Mazda America has in stock (price was actually pretty good) coming in the next couple of days.
Joined: Sep 2005
Posts: 25,581
Likes: 136
From: Smiths Falls.(near Ottawa!.Mapquest IT!)
Springer will ask you to be on the show Only if the Koyo radiator was sleeping with your Girlfriend and got her pregnant...Talk about a coolant leak...all those little freakin Bratiators running around now...
"I know they isn't mine Jerry..I was wearin a silicone hose".
"I know they isn't mine Jerry..I was wearin a silicone hose".
Springer will ask you to be on the show Only if the Koyo radiator was sleeping with your Girlfriend and got her pregnant...Talk about a coolant leak...all those little freakin Bratiators running around now... "I know they isn't mine Jerry..I was wearin a silicone hose".
Joined: Feb 2001
Posts: 29,798
Likes: 128
From: London, Ontario, Canada
I dont think any of the thicker aluminum radiators are going to fit with the stock air box. Your going to have to either settle for a stock size replacement (which will still be better than a stock one) or plan on keeping the koyo and getting a free flow intake. Decent price stock size radiators can be found on ebay for relatively cheap around 150ish iirc.
Of course it is 4X the price of the Koyo and others, but I guess one gets what one pays for.

Paid nearly $800 (considering shipping, duty, US to Canadian conversion) for my Fluidyne 13 years ago but it installed in less than 45 minutes and looks as good today as the day it went into the car.
I'd bet on my 2-pass for overall heat transfer vs any single pass including the fluidyne any day of the week and twice on sundays... 
It also fits with all that stuff in place except for the stock intake snorkel.
I have the corksport in my street car which is very similar in design to the fluidyne (no idea who actually makes it). It fit very well also and does not require the stock brackets. But, if i had it to do over I'd get another N-flow...
The airbox works with a lot of the big radiators it's the intake snorkel that only seems to work with the single pass koyo due to the rounded end tanks.

It also fits with all that stuff in place except for the stock intake snorkel.
I have the corksport in my street car which is very similar in design to the fluidyne (no idea who actually makes it). It fit very well also and does not require the stock brackets. But, if i had it to do over I'd get another N-flow...
The airbox works with a lot of the big radiators it's the intake snorkel that only seems to work with the single pass koyo due to the rounded end tanks.
I'd bet on my 2-pass for overall heat transfer vs any single pass including the fluidyne any day of the week and twice on sundays... 
It also fits with all that stuff in place except for the stock intake snorkel.
I have the corksport in my street car which is very similar in design to the fluidyne (no idea who actually makes it). It fit very well also and does not require the stock brackets. But, if i had it to do over I'd get another N-flow...
The airbox works with a lot of the big radiators it's the intake snorkel that only seems to work with the single pass koyo due to the rounded end tanks.

It also fits with all that stuff in place except for the stock intake snorkel.
I have the corksport in my street car which is very similar in design to the fluidyne (no idea who actually makes it). It fit very well also and does not require the stock brackets. But, if i had it to do over I'd get another N-flow...
The airbox works with a lot of the big radiators it's the intake snorkel that only seems to work with the single pass koyo due to the rounded end tanks.
OP I have a S5 radiator out of an 90 N/A vert which is in great shape, send me a PM if you want it. It's been in storage and last I saw it there were no bent fins, I believe the S5 brackets are still on there. You can have it cheap, but you have to pay shipping.
Koyo states that they only make the radiator for the S5 as a drop in. The S4 requires the mount to be shortened a little bit or drilled out. I cut and welded mine and it fit perfectly.
there is no direct drop in, it will still require some minor modifications but they are very easy to overcome. trim the radiator shroud to clear the hose in/outlets and it should fit fine. the koyos are the easiest to install short of the fluidyne radiators.
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