All right, getting ready for some cooling system modifications. I live in Arizona, and it’s hella-hot here (110+ for the past few weeks). Since heat is a major enemy of the RX7 I want my cooling system to be as bulletproof as possible. I’m not going to be doing a lot of performance modifications, but I’m certainly willing to spend good money on reliability.

I will say that currently the car performs just fine in the heat as is, and I don’t push it during extreme heat. And I open the hood most of the time after driving in the garage to help dissipate heat from the engine faster (my garage is hot as hell). The car has 58K miles on the original engine and such (1993 Touring).

I searched around but couldn’t find any threads covering tubing or fan specifics.

At this point the changes to the cooling system include at a minimum a new Fluidyne Radiator (with new cap), new thermostat, aluminum AST (with new cap), and aftermarket water temp gauge.

My questions:
1. Should I replace the water pump?
2. Should I do anything special with the electric fans (replace the motors if possible, looks possible from the shop manual)? Should I replace them? I ask because they are difficult to access, and since I will have everything out it is the perfect time to make updates.
3. Which hoses should I change (using the Mazdatrix site’s list, which seems comprehensive: http://www.mazdatrix.com/bhose3.htm)?

Once all of this work is completed I will perform the fan mod.

I plan on using standard “green” radiator fluid with Redline Water Wetter and distilled water (50/50 mix due to the climate). Made this decision from this extremely lengthy discussion: http://www.scuderiaciriani.com/rx7/cooling.html#ANT.

Finally, it’s a daily driver (not driven much as I work from home, but I don’t want it down for more than a weekend). So, if it comes down to replacing all hoses just to be safe rather than taking it apart and inspecting the individual hoses, I would just buy them all ahead of time and plan on installing. The question then becomes, which hoses should I purchase?

Thanks.

 

You will want to run a more water heavy mix than 50/50. You will probably want to run something like 25/75 or 20/80. Anti-freeze does not conduct heat as well as water. The 2 primary purposes of anti-freeze are anti-corrosion protection and anti-freezing (duh!). It does not significantly raise the boiling point of the mixture (the pressure does that).

 

You might want to look on this page/forum regarding the evans coolant. it's very helpful.

From reading that, i'd suggest you use evans coolant instead of your coolant mix. Apparently the redline water wetter contains chemicals that aren't for the system.

 

There are five popular cooling system mods for the 3RD Gen for the combined purposes of improving reliability and increasing cooling capacity. Remember, these cars are now about 10 years old. If your car has never had any cooling system work then now is a good time to do it all:

1. Replace the plastic AST with an aluminum one.

2. Replace the stock radiator with a larger capacity one. Fluidyne (1 1/2 inch thick) and Koyo (2 inch thick) make all aluminum aftermarket radiators for the 3RD Gen. Go to this link:
http://www.absoluteradiator.com/cgi...6cdc+1011592985

3. Modify the radiator fans with a switch that allows you to turn on the fans at any time. Go to this link:
http://rx7.voodoobox.net/howto/fanswitch/fanswitch.html

4. Change the thermoswitch that turns on the radiator fans to a Miata thermoswitch that will turn on the fans at a lower temperature. The Miata thermoswitch is available from aftermarket parts places. You also have to change the existing connector. Get the connector from a 90's something Ford Probe (Mazda engine) at your Pull-It-Yourself wrecking yard.

Alternatively, if you have the PFC, then buy the Datalogit which allows you electronically change the temperature at which the fans come on.

5. Recognize that the stock temperature gauge is actually an idiot light and either "linearize" the stock gauge or install an aftermarket temp gauge in order to get accurate temperature readings. Go to these links:
http://www.geocities.com/sdrx7_club/tempgauge.html
http://us.share.geocities.com/sdrx7...nstructions.pdf

Again, the PFC with commander can serve as a temperature gauge.

Finally: If you break into the cooling system to make any changes then also replace the thermostat plus upper and lower radiator hoses. Refill with only distilled water and antifreeze at a 75:25 water to antifreeze ratio.

 

I'm more interested in comments about replacing hoses and/or fan engines. Should I change out all of the cooling hoses? Do the fan engines go bad, should I test and consider swapping them (per the shop manual test procedures)?

Thanks.

 

IMO, I wouldn't bother replacing the water pump unless it's bad.

As far as hoses, there was a group buy for hoses made by Thermal Flex a while back. You can contact them and see if they will make you a set (I suggest calling as they only check email about once every 2 weeks):

http://www.thermalflex.com/automotive.html

Some people have asked about using different fans for the radiator, but I haven't seen anyone actually use any different ones. IMO, you would get a bigger benefit by getting a vented hood to help release the heat than trying to upgrade the fans.

Good luck!