85RX7GS

iTrader: (1)

Why bother using the air-oil cooler? The water-oil cooler seems to work fine for me. And since Mazda decided to use it on 84 and 85 Rx-7s, there must be some good reason behind that switch if the air-oil cooler was good for the older Rx-7s. I really want to know what the advantage is of switching over. I would think that if the thermal pellet (or whatever governs the oil temperature) in the radiator went bad during the winter, then the oil wouldn't heat up all the way and might not develop the viscosity needed to properly lubricate the engine. Anyway, I could go on, but I'll stop. What's the advantage?

peejay

It doesn't work fine. The water-oil cooler does a good job of preheating the oil. This gets the engine warmed up faster. Unfortunately, t's very hard to cool oil down using 180-200degF coolant. As the temperatures of the cooled medium (oil) and the cooling medium (coolant) get closer together, you need bigger and bigger coolers.

In short, the water/oil cooler cooks the oil. Witness how many '83-85 engines suffer from oil cooler O-ring leakage, or worse yet dowel O-ring leakage. When you take the old O-rings out, you'll find that they are literally baked into a hard brittle plastic. Engines with air/oil coolers do NOT have this problem.

Considering that the oil is approximately 40% of the cooling system, I would NOT skimp on it. The water/oil cooler is rumored to be cheaper but its main benefit (as far as OEM is concerned) is it gets the oil hot sooner. In '86 Mazda went with the crackpot oil bypass pellet as a different method of getting the oil up to temp faster. At least the thermopellet doesn't preclude proper oil cooling even when everything's working right.

85RX7GS

iTrader: (1)

What is the factory spec fot the oil temperature under normal driving conditions?

jr69187

i think it is up to 230 and at that piont things start to go bad. if you decide to go to the big cooler i have one for sale.

jr

Directfreak

iTrader: (2)

Yep. That arguement also goes out the window when you factor in that Mazda also decided to use the Air/Oil Cooler for their 1st Gen Bad Boy with all the upgraded goodies. - The GSL-SE.

jr69187

let me tell you i los my first 12 due to the damn oil water cooler got plugged with parts of the o rings and that is what toasted my 12 a. so i take those things off and blow the hell out of them with the largest calibur gun i can find. besides if the water coolers work so good why are they not on second gens. Do the math gs was a base car and those water coolers were cheaper so walla there ya go.

jr
crap is cheap quality is not.

82transam

iTrader: (18)

Not too mention the 2nd and 3rd gens. hmmmm, if the water kind "works fine" why did it only exist for 3 years?

the water one is ****, don't skimp when it comes to cooling. especially on a rotary.

85RX7GS

iTrader: (1)

Okay. I've got a cooler out of an SE. Would the radiator that I have in my 85 GS work with that cooler?

Pele

iTrader: (28)

Look up under your grille... Towards the left (If you're sitting inside... but Right from your point of view as you're looking for it.) side of the car, you should see a bracket with two holes... This is where the stock oil cooler was mounted on the SE... This bracket is present on all 1984 and 1985 Model year cars, regardless of style. My GSL has it.

82transam

iTrader: (18)

You would trust the life of your new engine with that thing? It didn't look like it could hold more than like 3 psi.

error402

I did the 2nd gen air/oil cooler swap on my '83 GSL and the temps are much lower now.

I would recommend it for everyone. Such a easy mod to do. If I knew it was that easy I would have done a long time ago.

-Error402

error402

I did the 2nd gen air/oil cooler swap on my '83 GSL and the temps are much lower now.

I would recommend it for everyone. Such a easy mod to do. If I knew it was that easy I would have done a long time ago.

-Error402

JEC-31

The number one reason I paid $160 for one of the most rotten 1st gens I've ever seen (an '82 with 220+K miles, apparently half off road and the other half in a salt mine by the looks of the chassis...) is that I found a 5 -yr old reciept in the glovebox for a new air-oil cooler and lines! My project '82's previous owner had swapped in an '85 12A with it's crappy water-cooler, and my old 7 is another 85 - so that parts-car's cooler was a diamond in a pile of poo for me.

Why the hell in 84 did they bump up compression, lighten the rotors, get more HP, and then downgrade the thermal management? Silly accounting decisions...

Manntis

Possibly to differentiate it from the "premium" RX-7s, like the SE.

Auto manufacturers o that all the time - where it'd be cheaper or better to use part A, they use part B in ""base" models so the models a bit higher on the food chain look better. Same thing happens within model lines; if the Porsche Boxter shares too many parts with the 911, which costs twice as much and has a fatter profit margin, they restyle the interior, change bumpers, etc. to further differentiate the models.

inittab

Audi did a similar thing with the A4 1.8t ...... they de-tuned the turbo for the US market so they could justify the markup on the "more powerful" 2.8 model. Well, all's it takes is a few hundred bucks for a chip and the 1.8t walks the 2.8 easily.

85RX7GS

iTrader: (1)

I just wanted to know what the advantage was in switching, as the thread topic states.

peejay

The water-oil cooler is a little cheaper and it gets the oil warmed up faster.

That's the "why" why Mazda switched.

The '79-82 style ofers much superior oil cooling. It does take longer for the engine to warm up, but the oil temps are no longer held hostage by coolant temps. Good luck trying to find a '79-82 engine with dowel O-ring leakage. Good luck trying to find a '83-85 WITHOUT dowel O-ring leakage... the hotter oil from the poorer oil cooler cooks the dowel O-rings and this requires an engine teardown to fix.

Note that even the GSL-SEs have a fairly poor oil cooler location - it's hard for the air to go through the oil cooler because it then has to go through the radiator, so it's easier for the air to bypass the cooler entirely. (Of course, all oil coolers DO have thermostats in them, but still... what a half-*** idea to put it in front of the radiator)

Also note that all '86-up cars have a thermopellet that has the purpose of - you guessed it - getting the engine warmed up faster.

85RX7GS

iTrader: (1)

Thanks for answering my question Peejay.

Anyone know a place to get oil lines (cheap) besides Mazdatrix?

BTW, I hope I didn't get anyone upset. I was afraid that I'd get nailed because this thread, but I never wrote it with the intent of discrediting anyone or anything.

diabolical1

iTrader: (3)

how cheap do you want it?
http://www.racingbeat.com/FRmazda1.htm

http://www.mazdatrix.com/b6.htm

or you can have them custom made by a local hose shop or buy the parts and have them crimped

www.summitracing.com

Don Bike

OK, so what is the best alternative to the water-oil cooler?

Pele

iTrader: (28)

Probably the Turbo II oil cooler as I'd imagine, it's bigger...

Any air-oil cooler would be better than that POS water-oil cooler though.

ASEmaster

Has anyone ever tried one of those aftermarket air/oil coolers like in a Jegs or Summit catalog? You know, the kind that comes with a remote filter mount? What do you think of using one in conjunction with the water/oil cooler?

jr69187

yeah it was a pain in my @ss so i went out and got a first gen cooler and had a new set of hose made. If you are looking for hoses i will have a definte price on them after this weekend. i have to make a new set and i will hofully be able to sell them for under 40 bucks shipped. also i have a big cooler but you know what those are worth and this one is mint i am think about 100 bucks for this one. i sold one on ebay for 175. those older coolers are getting harder to come by but i have a few laying around but they are not cheap. but i may be able to sell the lines cheap.

Directfreak

iTrader: (2)

Mike P-28 did. But then he needs it.

85RX7GS

iTrader: (1)

Thanks jr69187 and diabolical1