Koyo Installation Tips
 

For years I have seen threads about Koyo install issues. We have been installing them for 15+ years without any issues, so I figured we would snap a few pics of the most recent installation and the things we do to make for a pain free installation.

For the point of this thread we are going to assume the installer has the capabilities required to removed and install a stock radiator.

Lay both radiators next to each other.

https://cimg4.ibsrv.net/gimg/www.rx7...820404bf40.jpg

Install the fans, rubber grommets and brackets from the original radiator on the Koyo, everything mounts exactly the same way. DO NOT MOUNT THE BRACKETS UPSIDE DOWN, this is bad information that has been handed out on this forum for over a decade. Inspect the fan motors, to insure they spin freely and that the blade assemblies are not broken. Do not try to glue them back together.

https://cimg6.ibsrv.net/gimg/www.rx7...dbfd2b5c20.jpg


https://cimg7.ibsrv.net/gimg/www.rx7...6e9758c0ea.jpg


Next that car needs to be prepared for the installation. This is the bracket that causes the largest problem, it is the right side upper A/C condenser bracket. If you have removed your A/C then skip ahead.

https://cimg2.ibsrv.net/gimg/www.rx7...9778f4a27d.jpg

This bracket needs to be flipped over or removed. Once it is flipped over it allows the radiator to drop right in.

https://cimg6.ibsrv.net/gimg/www.rx7...a6a4e3f63a.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...aba4256643.jpg

https://cimg9.ibsrv.net/gimg/www.rx7...b934a47236.jpg

Next both the radiator bottom supports need to be bent slightly to accommodate the thicker radiator.


https://cimg3.ibsrv.net/gimg/www.rx7...bf291467de.jpg

https://cimg5.ibsrv.net/gimg/www.rx7...dc50329462.jpg

https://cimg6.ibsrv.net/gimg/www.rx7...3bdcab2420.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...c1dd598f7d.jpg

The brackets also need to be inspected for damage, we have seen countless bent brackets. As you can see this will raise the radiator, causing fitment issues. The good news is they are inexpensive from Mazda.


https://cimg3.ibsrv.net/gimg/www.rx7...8666185ca6.jpg


https://cimg4.ibsrv.net/gimg/www.rx7...0f2a3851bc.jpg

https://cimg6.ibsrv.net/gimg/www.rx7...bf39944608.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...1d3f32b177.jpg

Now the new Koyo will drop in.


https://cimg4.ibsrv.net/gimg/www.rx7...b8cf0a8db0.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...cf6ce24fc4.jpg

Remember to bend the low tabs back up.

https://cimg0.ibsrv.net/gimg/www.rx7...7e41105e0d.jpg

This is a great time to install new hoses and an upgraded AST. Now just put the car back together and fill with coolant. Remember to burp the system properly.

:icon_tup: This should be sticky

Awesome post, thank you! The pictures of the ac bracket help make it very clear.

Awesome! But i am pretty sure i didnt need to turn the bracket around on mine :) But this guide should be sticky!

^ only way it would go in without altering/removing the bracket is to damage the side of the radiator, which is something I prefer not to do when it only takes 5 minutes extra to install correctly.

Good info. I'll add that I usually get rid of the stock rubber lord mounts. This will allow the radiator to drop down even further and helps fitment if you have a stock intake and intercooler.

^ I never remove them and have not had any problems with installation of stock or aftermarket SMICs. The rubber mounts prevent premature wear.

write up on fluidyne please !! this is good thread

:icon_tup:Thanks!:icon_tup:

Thanks for doing this :icon_tup: I might take a look at my fluidyne and see if I need to adjust anything futher. It's hard mounted without the rubber isolator bushings and the upper radiator hose still seems to push up on the stock intake.

Fluidyne is straight drop in, no need to remove OEM radiator bracket or bend anything.

Fluidyne runs a minimum of 10F hotter, with an FMIC we see 20F

Remove them all the time

How does the Koyo compare to the Mishimoto radiator in terms of fitment and cooling.

The Koyo radiator is nearly twice as thick as the Mishimito. Mishimoto is easier to fit but often the mounting holes for the fans are often off and need to be drilled out. The bypass hose nipple is also the wrong size requiring an reducer. Mishimoto isn't known for quality. There is always some issue, though usually minor, that needs to be corrected.

Great info. Thanks.

I can't see from the pics if you have cut or bend the little tab (see picture) on the bracket? On my car I can't get the right angle with it.

Just added to the FAQ. Thanks Banzai.

+1 on Mishimoto sucking

Nice! Installed a Koyo Nflow 2 months ago in my 02 FD3S with no issues and perfect fitment!

One thing that i dont think you mentioned, is that the OEM radiator has foam on the sides, to stop air flowing around the radiator. I bought some soft but dense foam to make sure as much air as possible go where it should.

This is if you dont have any intake mods who pull air from this location.

Attachment 607221
Attachment 607222

Great info. Now I have to go back and redo my radiator a 3rd time. Lol.

I had some rubbing issues with Koyo radiator and my Greddy FMIC piping. The Greddy brackets are meant for the stock rad which is smaller. To address this i could have a made some new brackets to accommodate the bigger Koyo rad and try to drop it lower down. Instead I took the intercooler pipe it was rubbing against to the vise and a big hammer and made a few nonchalant dents in the right spots. The goal is to not crack or perforate the pipe, so take your time.
GL!

Outstanding, thanks. I have a Koyo sitting here ready to replace a leaking Fluidyne (not the Fluidyne's fault) and aside from being busy I've been noodling over how to make it fit with my stock airbox/Blitz SMIC/AC condenser. This thread confirms it's good to be a procrastinator sometimes.

I think between these tips and the possibility of adding spacers to the AC condenser, I should have things in order. For those that have lowered their assembly, did you have issues with the stock undertray pressing on things?

My radiator measured 58mm wide and I ran into the problem of it not going down far enough onto the mounting bolts because the mounting bracket on the rad is hitting the mounting bracket that's on the car.

I can see why some people turn those tabs upside down but that would prob raise the radiator and my stock plastics won't fit back up.

I'm just going to take the mounting brackets to work tomorrow and put them in the vertical band saw. It should clear after I take some metal out of them.

Just thought giving some heads up to other people with thicker cores. I believe other cores measure out around 48-53mm or so.

In Need Of part numbers
 

anyone have the part number for the two mounting brackets? Car came with a very old Fludyne Rad that has the brackets built in so I’m bracketless.

thank you

I was bracketless too. An easy alternative to the OEM brackets is to make your own, which is what I did. Just some AL stock drilled & bent in the right places, one bracket for each side. Here's pictures of the brackets on my Koyo to illustrate the basic design.


https://cimg5.ibsrv.net/gimg/www.rx7...0e38e0803f.jpg
https://cimg7.ibsrv.net/gimg/www.rx7...a1bd473609.jpg

hey, thank you for the reply and pictures! Most likely if I’m unable to get my hands on some OEM ones then what you did is the plan B.

appreciate you

I’m having a tough time installing mine..

it sits almost cockeyed and I can’t get it down on the brackets. The RH side fits into the bottom bracket hole but the LH side does not and the radiator makes contact with my oil cooler lines. My back hurts bending over pulling this in and out over and over but I can’t get it to fit.

any ideas???

https://cimg8.ibsrv.net/gimg/www.rx7...511de94c8.jpeg

I just finished installing a Koyo a few weeks ago. It went fairly smoothly (thanks to the great info on this thread) but one thing I didn't expect was how far I had to bend the lower mounting brackets down for the radiator to drop all the way down. Maybe something to check?

I guess I could try bending them more but I don’t see why it’s not sitting evenly... it’s like I can get the RH into the hole for the bracket but not on the LH side.

Also noticed the top bleeder is hitting my frame.


https://cimg1.ibsrv.net/gimg/www.rx7...a8bfcd7fe.jpeg

It's hard to see on the car now but I'm pretty sure mine didn't have that plug on the top.....it's like the picture at the beginning of this thread.

If it's not fitting right, then either the brackets on the stabilizer bar mount that the radiator "pegs" on the bottom sit in with the rubber bushings are bent/misaligned relative to one another, or the 2 studs/rubber vibe isolator mounts are somehow misaligned - maybe one of those isn't screwed in all the way, so it prevents the other side from seating?

Mine dropped right in, even with my quicky fabricated AL bracket ears, and I have the same top bleeder plug on my Koyo that yours has.

How far did you bend your bottom brackets?

I didn't have to bend those at all, the Koyo radiator dropped right in to those with the rubber peg pieces. Could be because the PO may have bent the brackets a bit to persuade the prior Megan racing radiator to fit in there.

I absolutely hate being stuck. I’ve bent the bottom brackets and still no luck. I’ve read countless threads on this install and it’s either 1) was no problem at all! Or 2) painful and how did they ever get it in?!

Im stuck in 2.... seems no matter what I do, nothing lines up. The stock radiator had no issues fitting.

Double check your stabilizer bar brackets and make sure one isn't bent. When I bought the car it had a Fluidyne previously and it sat okay. When I went to replace it with the Koyo it would not seat correctly at all. Found out my passenger side bracket was bent and after getting new ones the install went a lot smoother.

There may be some differences with your car being JDM. Also having the second oil cooler doesn't help, those hard lines get in the way big time.

You have an interference problem, something is keeping the radiator from going where it should. You have to step through and find where that spot is. I would also see if the stock radiator drops in still and compare how it fits to how the Koyo fits.

My guess is it may be the AC condenser it's fouling on. You may need to unbolt the condenser from the frame and let it hang down while you're working.

This is a job that needs access top and bottom and a good STRONG flashlight/shop light. Keep looking to find where it's fouling. You may have to do some trimming or move some things. TAKE YOUR TIME. Getting frustrated just leads to more problems if you start bashing on things or rushing it.

Is your radiator a regular one or the N-Flow? I'm still curious about that air bleed screw. Friend here in Pensacola got a new Koyo that was a regular one with no bleed screw.

Also post up some more pictures of the fit process. Top and bottom. We can figure this out.

Dale

Dale,

Mine is the N-Flo version. I've also posted this in our Emerald Coast Facebook Group. I'm wondering if I just need to get new brackets for the bottom because they may be bent. I can't see that they are bent, but I'm running out of ideas unless someone from P-Cola area wants to come help hahaha. Banzai and others have suggested this may be the case as everything else is saying it should fit while doing the steps outlined in this thread. I've even looked at the Australian forums and they report doing as Banzai has in the install. So, running out of ideas except the replacing of the bottom brackets.

Those brackets are actually the sway bar mounts. It is common for them to be bent. They are available new from Mazda, they aren't too pricey if memory serves. Hit up Ray Crowe on those.

May want to post pictures of those brackets.

Yeah, I've been posting some on the EC Rotary thread too :)

Dale

Dale just hit on 2 things I didn't have to deal with when my Koyo dropped right in - I installed my 2nd oil cooler & lines after doing the Koyo install, and I didn't have an A/C condenser at the time either. I now have all of that stuff in, and it all fits. A/C condenser is a generic 24"x12" parallel flow unit, which is about the biggest I could make fit.

A good flashlight, lots of patience and beer breaks is good advice here; post up some pictures of those strut bar/radiator brackets so we can figure out if they are indeed bent out of whack.

Just going to assume they are bent. Ordered new ones to hopefully fix the issue. Won’t get them until after Xmas. Thanks everyone! I’ll update the results when I can.

I posted pictures of bent brackets on page 1, when I created this thread. I also posted pictures of new vs. bent

That is why I’m going that route. Haven’t removed them yet but with holiday travel coming up, it’ll have to wait.

Keep us posted once they come in! Hope this will close out your problem.

Dale

I installed a Koyo N-flow in a 95 JDM car today, I can tell you that the installation is exactly the same, sorry there is nothing exciting to report.

https://cimg1.ibsrv.net/gimg/www.rx7...308d7594d.jpeg
https://cimg2.ibsrv.net/gimg/www.rx7...a41b8adb7.jpeg

Chris,

Thanks
https://cimg9.ibsrv.net/gimg/www.rx7...ce8cd8a2f.jpeg
for the help in the thread about the brackets... it looked like mine had some slight bends and once I removed them and installed it with new brackets it went in immediately.

The N-flo and condenser are also very close! I did do the bracket flip too.

Only weird issue I found was that silicone mishimoto hoses for the bottom aren’t an exact fit...? They are a little bit longer than the factory ones and I had to really make sure not to kink it.

Car now has new coolant in it and the burping process begins...

If the hose is a little long you may just need to trim it. Use a long razor knife and put a hose clamp around the end you want to cut, saw along the hose clamp using it as a guide. You'll get a clean straight cut.

Glad you got it in! It doesn't take much for those brackets to be wonky.

Dale

What do people use to replace the side foam on Koyo, and where do you get it? I saw only one post on that?

Rad side foam?
 

where did you get that foam to use on the sides? How thick is that, it looks much thicker than stock?