Just wanted to add some comments here. I've had some cars (early '90s) that did this, but then more modern cars that did not. I don't question Mazda engineers, but I'm kind of wondering why it's necessary because it's not like the coolant is circulating at this point since the water pump is not being driven. Seems pointless to just cool the mixture in the radiator. But perhaps if it cools the mixture in the radiator, it also helps to secondarily cool down the mixture that's in the "block" because it's pressurized. Seems kind of unncessary, but then I'm not an engineer. I just know that I've had some cars that did this and some that did not, and yes, of course the fans shut off after it hits a certain temperature, they're not gonna run forever, unless your temperature switch or something else is mucked up. Maybe it all just boils down to how they elected to do the wiring, some cars requiring the ignition to be on, others not, and it really doesn't need to run, just the way they wired it. Of course, I wouldn't disable it to shut off with the ignition. I don't see it hurting anything at all either way, but again, I'm not an engineer. I guess the real question is: Does having the fans react to the temperature switch after the ignition is off necessarily prolong the life of the engine? Who knows, but I figure it can't hurt. This is a good thing. I wouldn't worry about the battery at all.

I wonder if the twin-turbo Rx-7 did this?

 

it is in the manual

 

The last three or four cars I've owned have done this. It is normal with an electric fan and it's designed to do this. Their is no point in restarting the car to turn the fan off as it will shut off automaticlly when it gets ready.

I haven't looked at the RX-8 but most cars have a warning/caution sticker saying something about being equipped with an electric fan than can run without the car running.

 

there is a cutoff programmed into the pcm that will turn off the fans if the battery voltage gets too low. ur battery wont die when the fans turn on while the car is off. the rx8 has two fans. both spin while the car is off. it blows air onto the front end plate to help cool the engine down. yes its normal. my friends 300zx does it too. why do people care what the cars doing after u walk away? if it sung the zoom zoom theme song i could care less too. let the fans run and dont interrupt it

 

Fairly certain why this works: The entire cooling system is filled with coolant. The fan runs and cools the radiator. The cooler fluid in the radiator sinks (because it's a higher density cooled). It sinks it's way into the engine and displaces the hot, lighter density engine coolant into the top of the radiator and the clycle repeats. Probably timed to shut off the fans before the thermostat closes.

This is called thermal syphon. Early water cooled race motorcycles used this system and got away without needing a waterpump. Of course back then you had to be moving for it to work (why it didn't pan out for street bikes), and you can't be generating huge amounts of heat (because you can't circulate the coolant fast enough) but nowadays the fans can provide the airflow and, with the engine off, heat generation is not an issue..

 

convection and thermal syphon- yes it works

 

Point taken.

However, you should consider zipping down to the Mazda dealer and get the upgraded battery, starter and leading plugs before your warranty runs out.

 

On that warranty mention, up graded battery, starter and leading plugs?

Did I miss something?

 

saw the bulletin on the battery.

saw the one on plugs for cold weather.
Didn't see the one on starter. Or is there a recenty one on all three?

Looked at Rosenthal site.

 

The definitive service bulletin on flooding is "Engine cranks no start" at http://www.finishlineperformance.com...4-05-1448e.pdf . The first page lists the four upgrades Mazda has done to reduce/eliminate the flooding problem:

- PCM firmware update
- 640 CCA battery
- bigger starter
- redesigned leading plugs

Each change is noted with the date it was added to the RX-8 production line. Some dealers take the position that, like the typical service bulletin, it is not appropriate to do the work unless you actually flood the car. However, MNAO seems to be OK with authorizing all the updates for older cars on a preventative basis, even if they have NOT flooded, so if the dealer says no, call the Mazda 800 number.