Cody Helton

Well it seems my radiator has sprung a leak, a decent sized one too. Im going to replace my radiator obviously but my rx8 is a 2004 six port MT. Is there a difference in the radiators between it and a 2005 rx8? The reason why im asking is because a 2004 radiator is $100 and a 2005 is $55 with a lifetime warranty.

2005 radiator-
https://www.buyaradiator.com/product...SABEgJP3fD_BwE

2004 radiator-
https://www.buyaradiator.com/product...or-rea41-2695a

Why the huge jump in price? Also I noticed that both model years of radiator have a variant with 2 small pipes on the bottom. (The 2005 one I linked does, but it also has one without them.) What are these for? To save $50 can I just get the 2005 and put it in my 2004? Should I get one with or without the small pipes?

Jedi54

iTrader: (7)

get a Koyo radiator and call it a day.
AFAIK, the 04 and 05 should utilize the same radiator. Beware of some of those cheap knockoff radiators as they might fit well and some are quite brittle.
also, when you replace the radiator, make sure to re-use the foam that surrounds the radiator to ensure proper airflow to the rad.

Steve Dallas

The one with the extra "2 small pipes" is for automatic transmissions. That is the transmission oil cooler.

Buy a TYC or a Denso. Don't waste your time and money on one of the cheap-O knock-offs. This radiator isn't exactly easy to replace, and it isn't worth having to do it twice to save a few bucks.

2005 MAZDA RX-8 1.3L R2 Radiator | RockAuto

But, I'm with Jedi, all the way. Buy the Koyo all-aluminum or the CSF all-aluminum and be done with it forever. Get better cooling capacity as a bonus.

Be careful with the coolant bottle, when you change the radiator. It is easily broken, and relatively expensive.

Cody Helton

Yep, ill go with the TYC, same cooling capacity as OEM just no leak lol. I was looking into those.

gwilliams6

I recommend the Koyo. Many here in the club have found good success with their quality and affordable V-core unit. I have one and it is excellent.

Cody Helton

I havent pulled the trigger on one yet, but I definitely will go aluminum based on what ive read and get 2 cores instead of one. One question, would I need to change the pressure I run in my coolant AKA get a different cap if i get a aluminum 2 core radiator opposed to the stock one? Also ive noticed a lot of aftermarket aluminum radiators for a little over 100 dollars. Do these have a major problem?

Ill link one here- Aluminum Radiator For Mazda RX-8 04-08 40th GS GT Sport Touring R2 1.3L MT 05 06 | eBay

Would this provide a little upgrade over OEM cooling? Do I need a different pressure cap? Do these have any major issues?

Cody Helton

Also would I have to buy generic radiator fans or would my stock ones bolt on?

gwilliams6

Unless you have special needs for a FI engine or race your car fulltime, a Koyo V-core would be a great choice, a top quality, reliable and affordable all-aluminum upgrade from a known manufacturer, with proven record with RX8 club members.

Some of these ones I cant even tell who really makes them, and there is no track record here on their quality, reliability and longevity. Your engine can't afford you buying anything suspect, just because it is cheap.

Also the Koyo and a few quality others are direct bolt-in without any modification and fit the oem fans perfectly. I don't see this direct bolt-in guarantee on the one you linked. Some aftermarket rads have required some mods to fit. You don't want to hassle with that.

Not saying I know for sure the one your linked is bad, but I wouldn't take a chance without another RX8 member verifying its quality and fitment.


https://www.google.com/search?q=koyo...w=1042&bih=721

Steve Dallas

I can't recommend buying an eBay radiator. You never know if it will fit, nor how it will perform, nor how long it will last. Not worth the gamble to save $100 in my mind. Koyo and CSF are the two radiators that are known to fit and be of high quality. Honestly, if you don't want to spend the money on either of those, I recommend buying the Denso from Rock Auto. It is probably better than any eBay radiator, no matter how shiny, and it will definitely fit.

You can reuse the stock fans with the Koyo and CSF radiators. It's hard to say if the shroud will bolt up to the eBay radiator. The mounting bosses on those are often off by a few millimeters.

It is worth thinking about replacing the fans/motors, while you have everything apart. The early fan motors are weak and tend to slow down with age.

.

Cody Helton

Yeah that was my worry about the Ebay ones. I know i'm pretty indecisive about the whole situation but what I may end up doing is going with the plastic denso, but to help aid cooling buy a new fan assembly or motors. Not sure what would be my best option as far as the fans go though. OEM or aftermarket? I want some type of upgrade for this Florida heat... Anybody with a good set of fans/motors that will have an advantage over stock (let the engine run a few degrees cooler) for less than $100 drop a link if you can find it.

bluetii

iTrader: (3)

Hey guys just bought an 8 looking to upgrade my radiator too. As far as I know its the original. Considering the Koyo but is it really worth it over stock? I just bought my 8 as a second car. I just use it for weekends. Just curious. I have a stock Rx7 convertible and never had any issues with the stock Radiator.

Steve Dallas

Unfortunately, there is no such thing as a fan that will outperform stock for $100. The known good option is the FAL 420 shroud, which barely costs more than stock replacements. I *think* you can replace just the stock motors, but a quick search did not turn up a source.

The RX-8 is a much different animal than the RX-7. Cooling is a real problem with this car in warm climates. The Koyo V Series radiator is much better than stock. The CSF seems to be comparable to the Koyo.

NotAPreppie

Don't cheap out. You will regret it. Like I've told you before, this isn't a car that responds well to cheap owners.

Pay now or pay 10x later.

Do your fans work? If so, get a better radiator. You aren't going to find a reliable fan upgrade for the price you are looking for.

You really should get a radiator with a thicker core anyway. Might as well get the or radiators.

Yes, the Koyo or CSF radiators are worth it if you live in a warm climate or track the car.

You can.
https://www.jimellismazdaparts.com/s...ssembly=299669

They're $190 each. Better just to get the FAL 420 at that point.

gwilliams6

Remember your radiator helps keep your engine alive (which is worth several thousands of dollars). The Koyo and CSF are inexpensive compared to the cost of a rebuilt overheated engine.

Quoting NotAPreppie: "Don't cheap out. You will regret it. Like I've told you before, this isn't a car that responds well to cheap owners.

Cody Helton

Ok so my best option is Koyo/CSF , and I can bolt on my stock fans?

Cody Helton

And I take it the Koyo is 2 cores and should deliver better cooling? (Ive been reading other treads that say its just an OEM replacement, not an upgrade.)

NotAPreppie

Yup. Direct replacement.

There are two Koyo radiators. There's a direct OEM replacement (plastic end tanks and all) and there's the upgraded all-aluminum "racing" radiator. You want the second one. I linked to the correct CSF and Koyo radiators in my earlier post. Pick whichever one you like and run with it.

Steve Dallas

Stock fan motors are a little cheaper here at $163 each, but still better to get the FAL shroud.

The Koyo V Series for S1 cars is an upgrade over stock in every aspect. The Koyo HH Series for S2 cars is an upgrade in some aspects. The CSF is apparently comparable to the Koyo V Series, according to several members.

claybaby

My AC started blowing hot then cold while moving and my fans started staying on longer and longer my radiator light started staying on a few months ago but thought it was just a sensor so I have been keeping an eye on my coolant living here in Fl is so HOT wondering if my radiator is going bad?? I can't find anyone where I live to work on the RX8..Im in Lehigh Acres,Fl. near Ft.Myers..just put coolant in and drove home from Walmart and I see coolant dripping....looks like the overflow hose is wet inside...Bre

Steve Dallas

The RX-8's cooling system is just like that in any other car, and troubleshooting and diagnosis is the same. Any reputable shop should be able to chase down the leak and replace the offending part. That normally involves a pressure test and perhaps dye. Just be sure whatever replacement coolant is used is FL-22 compliant. Push back if a shop tells you coolants are all the same. They absolutely are not.

claybaby

well yesterday my 2004 rx8 over heated,,,all the coolant came out the overflow I don't see it coming from any where else..my air was going hot then cold while moving a couple of days ago everything looked fine so warnings signs but then it shot up with just two rides around the block I live in Fl its VERY HOT my fans have been staying on for longer I don't know how to work on my car and am having trouble finding someone in my area that will even look at it,,can anyone tell me where to even start to look in research,,,water pump??? thermostat?? radiator??? any help much appreciated

Steve Dallas

I don't want to scare you, and this is not a proper diagnosis, but...

If coolant is being forced out the overflow, it is under too much pressure, which likely means a leaking coolant seal, which means an engine rebuild.

Having said that, losing small amounts of coolant through the overflow is normal in these cars.

Where do you live in FL? Petit Racing is in FL. There are several Mazda dealers scattered around FL.

Nisaja

Sorry for replying to an old thread, but I'm planning on buying the Denso automatic radiator for a friend of mine. Is this a legit company? I'm seeing a lot of 1 star reviews online. I'm worried because I live outside the U.S. Their website says they ship to my location though...

NotAPreppie

Denso is large company with a wide variety of products. Their products are targeted at a certain value/quality ratio. Their products are engineered to meet OEM specs and they used to be a common source of OEM parts to various manufacturers (not sure if they still are but their OEM page is closed now).

If your friend just needs to replace a broken radiator, you'll probably be fine. If you're looking for something that performs better than stock, look elsewhere.

Nisaja

Thanks for the reply. I don't mind getting the Denso, but I've seen a link posted here for an aluminum radiator on Rock Auto. I can't seem to find it. All I see are plastic OEM replacements. The Denso automatic radiator is $86. I don't mind spending a few more for an aluminum radiator. Is there a cheap dual core for around $150? I checked out the Koyo and Mishimoto but couldn't find any automatic ones.

Also, how safe is rock auto? I'm reading a lot of bad reviews about them