potatochobit

iTrader: (1)

today was over 100+ degrees here in texas as pretty much everyday this summer

I have been driving short distances for the past few days and force the fans on
I also have my turbo timer set at 5mins to keep the acc on with the engine off
the fans run 5-10mins each time and usually longer
can this drain the battery down quickly?

my battery was dead when I came out of the store today
I plan to check the alternator this weekend but was wondering if running the fans drains the battery as bad as leaving the lights on?

adamrs80

iTrader: (7)

I'm down in San Antonio and I've had the same problem. I have the Pettit fan switch and the fan recall mod so my fans run more often when I'm driving and then at shutdown. I have trouble starting the car after I make a few short trips. I've considered the higher output alternator that IRP sells or maybe a better battery. It is an annoying problem and I pretty much have to charge the battery before I drive. I think it ruins an otherwise good battery by draining it down so much.

Any advice would be appreciated. Would the 140 amp alternator do the trick, or an Optima battery?

arghx

iTrader: (3)

An Optima or some other kind of high capacity battery would help. I don't know about a high capacity alternator. I have a custom 120amp on my second gen. If you ever look at an alternator "dyno sheet" , which basically shows output versus speed, you'll see that the rated output is not achieved in the idle range.

wstrohm

YES! Also see my posts #67 and #68 in Dale Clark's thread.

DaleClark

iTrader: (55)

^Ditto, read my thread on this. Take the recall crap out, there's no good reason for it and all you're accomplishing is killing batteries.

Dale

1QWIK7

iTrader: (33)

My car has the recall done. It does help during the summer. Only thing is you have to monitor it. When I would go on drives in the summer, id park where im at and pop the hood and leave the key in the on position. That way when a certain temp is reached the fans come on automatically and then turn off at a certain temp..

It helps when you wanna cool the engine quick from heatsoak or when you're at a gas station filling up etc.

Other mild days I just pop the hood with no key thus fans not coming on automatically.

adamrs80

iTrader: (7)

Great advice fellas. Being as hot as it is down here in TX I would rather have the expense of a higher capacity battery and have the additional air movement underhood at shutdown. I pop the hood every time I can but there are times when it does not make sense. My original vacuum hoses were still soft in Feb. when I replaced them, maybe the fan mod helped.

potatochobit

iTrader: (1)

hold on guys, I'm not following you exactly
once the car is heat soaked, how am i supposed to cool it down when I park if I remove the recall?
I understand it would help the battery drain problem but I dont see how it is beneficial to the motor.
I looked at dale's thread but all of those modifications seem to have to do with keeping the car cool while it is running.

today was so hot, that even an hour after I was letting it sit, the coolant buzzer came on for a minute when i put the key back in since it did not have a chance to thermosiphon back yet. Are you saying the engine can handle this kind of heat as long as it is not running?

btw, the rx8 has a similar function built in, the fans are always coming on at shut down

Prôdigy2nd

iTrader: (3)

As stated, if you pop the hood and let the engine bay cool out (it's faster with fans still on for a few minutes), *not that big of an issue, I know personally with the good down I've temps keep constant for a while after shut down, (watching on Power FC) but with hood open, it cooks down quite fast, 20-30 degrees in 5-10 minutes...*

That's how I limped home once (4 miles away) and it wanted to over heat, so drove tiny bit, stopped popped the hood, cooled down, then did it all over again, and a few times... Lol

The things we do for these cars...



J.

ttmott

iTrader: (1)

The fan recall modification was Mazda's response to deal with high underhood temperatures after the car is turned off. There were some engine fires on the 93 models due to the residual heat buildup. The modification was solely designed to run the fans for a period of time when engine ignition was off and certian coolant temperature parameters were met within a certian time before ignition was turned off to rid the underhood heat.

So yes the mod can run a battery down if the battery or charging system is not to specification.

Sounds like the OP and others are trying to rationalize the recall modifications to cool the engine. The only thing it will really do is bring the radiator temperature down. I highly doubt the coolant system will thermosiphon to any appreciable value as there is very little gravitational differential in the coolant throughout the system and the radiator is the low point (hot fluids are less dense and will rise...)

Temperatures here in florida &@!$ hot and I drive the car around periodically in the peak heat. On my PLX display the engine temperature measured at the fill neck adjacent to the engine's temperature sensor has never indicated over 100C and when it is that high I never immediately turn off the engine when parking. I monitor the temperature until the fans cycle off and then shut the car down. You can also turn the AC on and the engine temperature will come down faster at idle due to the higher fan speeds. The cooling system in my car is as Mazda designed it except for a Koyo radiator and metal AST; I simply make sure it's in good repair and operating correctly. Other things on my car that helps is the pre-cat has been replaced with a down pipe and I have a M2 vented hood.

Now with all that said - if you have changed the thermoswitch to the FC thermoswitch and keep the recall modification you will notice that the fans will tend to run after the engine is off at lower temperatures as the switch for the FC closes at a lower temperature and the recall mod black box starts it timer when the thermoswitch is activated (which by the way I have rarely seen and I have the FC thermoswitch).

To cap all of this off is I also have a PC680 battery which if the fans run after the engine is off it will kill the battery. I watch all of this carefully but never have had a problem.

1QWIK7

iTrader: (33)

Heatsoaking begins when you become stationary. Whether its sitting at a light or when you park the car at home and shut the engine off.

Heatsoak is accelerated when you shut the car off because now there is no more coolant flow and all that heat is just sitting in the engine bay with no where to go.

you can pop the hood which does help A LOT. You can leave the recall and have your key in on position and let the fans come on and off according to temp.

If the weather is really hot, your recall CAN run your battery down. That's why I said you have to monitor it. Because it will take longer to cool the engine due to the high ambient temp thus leaving those fans on longer running your battery down.

Heatsoak is a real killer to these cars. Anything you can do to reduce the heat at anytime running or not, will help.

wstrohm

Or, if the engine's on time is just not long enough to recharge the battery, even though the battery/charging system meets all specs. A bigger battery won't help that, nor will a higher-capacity alternator. Somehow enough amp-hours have to be added back into the battery to exceed the number removed by the fan circuits over time.

adamrs80

iTrader: (7)

So I would say that the solutions for those of us whose fans are running down the battery would be the following:

- Drive further to re-charge the battery
- Re-charge the battery once home
- Buy a larger capacity battery and recharge less often
- Install a higher amp alternator which may help some

Or

Remove the fan recall and allow significantly more heat after shutdown in the engine bay.

I'm sure we all do, but if you're not already popping the hood after shutdown whenever possible, than start doing it.

DaleClark

iTrader: (55)

I pulled the fan recall junk out of my car shortly after I bought it in '04. I daily drove my car for a year or two in that point of time and have put about 60,000 miles on the car since then.

Guess what? I have no problems with heat that the fan recall would have helped. My wiring is still nice, everything is just fine. BTW, this is in Florida heat too.

Keep your coolant temps down, get a ceramic coated downpipe on there, and you'll be fine.

What is it that you're helping by running the fans after the car shuts off? It's not really making a damn bit of difference.

Original poster, you're saying your coolant buzzer is coming on after shutdown? It should NEVER come on, you've got some other issues you need to work out there.

Dale

adamrs80

iTrader: (7)

I do have my downpipe wrapped, not ceramic coated but I did use a good "titanium" fiberglass wrap, by DEI I think. I have a Koyo radiator and my temps stay low. I am going to leave the fan recall on for the same reason Mazda installed it to begin it. Piece of mind if them and their customers. I am not worried about the car catching fire. Statistically I'm sure most of the RX-7s would have never caught on fire but since there was some risk Mazda did what they thought was best at the time. Other than the hassle with battery drainage I can't see how running the fans would not help the engine bay cool down at least some. Since we have no real way to compare wiring and vacuum hose brittle-ness between all the FDs out there we will never know if it makes a difference. I would suspect the fans help some, maybe not much, maybe a good amount. Since we can not measure or quantify how much the fans help it will come down to an individuals choice on whether or not to keep the recall.