While looking at the radiator from the front of the car through the intake, I've discovered a very small amount of coolant leaking along the top edge of the radiator - about 4 drops a minute - after the car warms up.

I took the air box out and the inlet hose appears to be sound. After the car idles for 5-10 minutes, I can see a small amount of steam coming from a plastic assembly of a sort, directly behind the fan assembly - six inches to the right of the inlet hose. The steam seems to be coming from an area where there are some bolts that mount the fan assembly to the plastic piece of the radiator. There's a small stain of coolant along the top of that plastic, as well.

I can't see a leak directly, but reading accounts of the construction of the radiator, with it's plastic end pieces, am I to assume the radiator is leaking - probably where the top plastic cap comes into contact with the metal fin assembly? Could it be anything else? There are no leaks or stains around the filler assembly or hoses in that area.

Also, if it is the radiator that is leaking, would you fellows recommend a Fluidyne as a replacement? It's kind of expensive. Are there any cheaper alternatives that would work for someone who is planning to autocross?

 

1. Yes, the end tanks often lose their seal and leak, so a new rad is needed.
2. For normal use, and especially the low speeds seen in autocross, the stock rad is, IMO, better than many high-performance rads due to the OE rad being thinner and having better fin design, and, thus, better cooling at low speeds and air flows.
3. A fluidyne, etc., will be better for high speed racetrack use, but even then, there may be fitment issues.
4. The stock rad cannot be beat for low weight.

I would recommend getting a stock replacement from Ray crowe at Malloy Mazda (888-533-3400). He gives great discounts, knows his stuff, and ships quick.

 

BTW, my 1st comment above about the end tanks losing their seal applies almost exclusively to 10-year or more old radiators. IMO, a new one won't have this problem for many years. A large % of current OE radiators are made this way, and function very well for the life of the car.

Dave

 

i don't know about a stock radiator cooling better, even at lower speeds, the koyo and fluidine radiators are larger and hold more coolant, so they have a higher cooling potential even if the air can't flow through as efficiently. Once i had a certain amount of mods my stock radiator would overheat even at lower speeds. Once i switched to a fluidine my overheat issues were gone. Also The aluminum end caps would allow a certain amount of increased heat dissipation over plastic.

 

Not to argue, because you may be entirely correct, but you probably switched from (I presume) an old, well used, and maybe not in perfect condition OE rad to a (again, an assumption) brand new, perfect Fluidyne. And, if IIRC what people generally do, they install lower temp fan switches, improve the air ducting, etc., along with the radiator swap. So, are your results really an "apples-to apples" comparison?

Dave

 

Well at the time when i did mine the stock one was old but it was clean and the fins were protected from the ac condensor. It worked fine until my mods and texas heat. I didnt do any fan modifications until recently with my new engine. My fluidine cools great now with fan mod no ducts front mount and ac cond. But the fans do run alot without the duct so i'll be putting it back.

 

Well, you never know about the internal condition of the old rad, even if you have it tested, so it's not entirely apples-to-apples. But, hey, as long as it works for you, it's good. It was an academic question, anyway.

Dave

 

Go with the Fluidyne. You can search on here for other threads on this topic or check out the FAQ as we get this question often.

 

i think the fluidine is supposed to have better fitment but the koyo is supposed to work well too. i think there was another brand that wasnt as well known but had good results being a similar design to the fluidine/koyo's. can't recall the name of it.

 

mazdanikon----- just went through the same same issue. did my research and thread and all. and the fluidyne was purchased and the install took 1.5hours.
fitment is perfect.
-no cutting
-no relocating anything
-lowered the op temp of the fd
-no duck tape
-no welding
-no headache
-you get my point LOL
good luck!!!!!!!!

 

The fluidyne tends to fit best of all aftermarket "upgrade" radiators. It's one of the most compact and the quality is very good. Koyo, PWR, etc are thicker and tend to not fit as exact drop-ins.

A new or low mileage OEM radiator is a reasonable option, the primary issue with any plastic-tanked radiator is age and heat exposure. With a newer radiator of identical construction it's safe to say it will last at least as long as the original. The fact that you (should have) installed a few other cooling mods like a cooler thermoswitch will only help that.

Dave

 

^^^^ +1 love my fluidyne

 

Thanks to all for the above advice.

While doing some research across other sites, I found an article on modifying RX7s written by Sportscar Classic Magazine. There was a mention of a company called AWR that manufactures their own racing radiators. The description of their radiator sounds a lot like a Fluidyne, but SCM said the radiator was the best they'd ever seen on an RX7.

Here's a link to it.

http://www.awrracing.com/store/produ...&products_id=5


Price isn't cheap. About $500.


Also they brought up an interesting point about aluminum radiators that deals with electrolysis. They posted this interesting read and test for voltage issues in the cooling system. Here's the link:


http://www.awrracing.com/media/electrolysis.pdf


Anybody have an opinion on AWR radiators or on the electolysis issue with aluminum radiators in general?

 

Thanks for the info, didn't realize the issues with electolysis.

 

Oh, that's the Mazdaspeed radiator. I have heard it's quite good, and as you can see it's very compact (good fit).

Electrolysis is definitely worth checking. I'm not sure that the 3rd gens have electrolysis issues due to grounding specifically, but it has destroyed some engine cooling passages.

 

The Mazdacomp radiator works well, but if I recall it is slightly smaller and more expensive than the fluidyne. Getting a new stock radiator is a waste of money in my opinion. I've seen many destroyed coolant passages as well. Every time was a result of the coolant not being changed often enough and running tap water. One individual even used an expensive bottled water which has EVEN MORE minerals. Green coolant and distilled water only! Green coolant has a life of three years. I would change it at 2 years max in these cars.