Aseras

After I drove home today I stopped in the driveway, turned off the car took keys out locked it was talking to my cousin and the radiator fan was still running, full speed. It was LOUD. I let it go a minute or two and then unlocked the car, put the key in turned the key to on and it instantly went off. WTF is up with that?

Anyone else ever have this happen?

Socr8tes

So it begins...

jbrasure

The fan will run for a while if the engine is really hot.

clmantis21

it's just cooling your engine....

cLLcLe

Don't intterupt it... There's a thermistor that senses the engine heat that tells the fan to turn off or on.

Pretty much.... too hot = fan will run for a long time. And you do know that the engine is at it's hottest point AFTER you turn the car off right? It's because coolant stops flowing around the engine...

harwax

Don't feel bad, I had the same problem 2 days ago (fan didn't shut off after I shut-off engine) and did the same thing, turned engine on for 30 seconds. When I shut engine off fan stopped. Next time I will let fan run.

FoxTypeR

Now that summer is starting to get into full swing, it will be interesting to see how many of these threads we end up with. This should be a summer-time sticky or something.

Glyphon

way back in the late 1800s research was done on creating horseless carriages and through the great deductive reasoning ability of the human species, such a contraption was created. and since then, there has been never ending work and research done on how to improve these "auto-mobiles" as they were dubbed.

one of the design components on these contraptions is the radiator. the radiator is a giant heatsink to cool the fluid running through it, which in turn keeps the engine temperature from getting to high and destroying the engine.

as engine technology has developed over the past hundred years, it was necessary to add 1 or more fans to the radiator to increase its effectiveness. when the temperature coolant (the fluid that flows the engine and radiator...to help in cooling) rises to much, and the radiator is incapable of sufficient cooling, these fans on the radiators turn on, and force more cold air through the radiator.

this typically happens when the car is stationary, because when the car is moving, there is enough air moving across the radiator to keep the coolant at the desired temperature. when the car is parked and shut off it is stationary (hopefully ), so even though the engine is turned off, the fans will still run if needed to keep the temperature at or below the regulated temperature.

guy321

How many threads asking this question do we NEED? This happens on most new cars made within the last 5 years (some cars had it alot longer). Why do people still not get that the fan can run while the engine is off? :o

Not to attack the originator of this tread, but there's actually a bunch of threads on this, and one of them is still in active discussion within the past few days.

RX-GR8

yea what guy said. :D

Socr8tes

Yeah, I'm pretty sure the '97 Jetta VR6 my gf had at the time did this. That was 8 years ago for the mathematically disadvantaged. This isn't new technology.

pcimino

My dad had a freakin' 81 Reliant K car that had it, and I'm pretty sure our '78 Malibu had it as well.

Good thing I didn't inherit his "gene for car selection"

army_rx8

^hehehe

alamike

In a closed up garage, the fan is louder than others. It might be all the plastic packaging in the engine compartment. It also does not seem to be consistent with outside ambient temperatures when the fan says on or goes immediately off. It concerned me the first time it kicked on after engine cutoff this spring but I used the search function on the forum before posting.

Mugatu

iTrader: (1)

god, someone close this thread.

juikster

I havnt found in search where someone has either changed the thermister or adjusted (thermostat) if applicable to get the motor to run at a lower temp...Is it possible and if so can someone explain on how to go about it ...If I could lower the settings ,I would certainly do it

Aseras

ok there's something definetly wrong. it did it again today and it ran for a good 45 minutes before I went out and flipped the ignition off and on. that isn't normal.

Does the rx8 even have a electric water pump?

truemagellen

maybe you are running low/dangerously low on coolant...fans have to stay on since fluid is ineffective

Aseras

if it's thermistor driven it should not turn off instantly with the flip of the ignition should it? and no, it's perfectly fine on coolant, and proper mix and it's got plenty of oil.. just changed it.

and if it doesn't have an electric fuel pump running the fan after ignition off is perfectly useless.

it turns on the instant ignition is turned off and runs until the ignition is turned on and off. you don't even have to start the car.

Gomez

Do you have a standard intake? The fans run as a result of a signal supplied from the PCM. The PCM receives inputs from the MAF/IAT sensor in the intake which measures the intake air. The PCM uses this signal as an under-hood temp signal and switches the fans on if the temp is too high. If you've been fiddling about with the MAF connector after an intake install, you may have an intermittent connection. Re-seat the connector.

The other PCM input is the ECT (engine coolant temp) sensor. It's located on the LHS of the engine as you look at it from the front, at the 9 o'clock position.

The Renesis doesn't have an electric water pump, BTW.

Gomez.

Aseras

Yeah mine's all stock. Hasn't done it since then. It's only done it twice. It's been totally random. I've driven it hard and never had it do it, the first time it did it after a 3 mile run the the gas station and back. The other time was after a 100+ mile drive across the state.

I'll check the connector and reseat it and put some silicone around it ( I've got the gel we use for phone jacks ) to make sure it's not shorting out and corrosion free.

MI_FamilyMan

If anyone cares, this happened to me for the first time... I was kinda surprised, but it ran for about 5 minutes or so and it turned off itself. It is pretty hot here today. When I left work my temp was reading 101. Yikes. The fan noise does seem to be a little louder than other cars I've had that did this.

I wish that bird hadn't pooped on my car right after I had just got done washing it... Grr...

DOMINION

This has happen to me too.
My fan was on when I went in side. When I went back out 30min later it was still on. So I opend my hood got in the car and just as I put the key in the fan went off.
I calle my dealer and they told me its normal. B.S.

DOMINION

Oh yea I for got to say: Its like 113 where I live in Las Vegas right now and I was driving with the A/C off!...

Aseras

i dunno I only had it happen 3 times so far.. like 1 out of 50 drives i guess. I figure the fan will probably have to catch fire and burn my house down before mazda does anything about it.