Fan on after shut down, how long?
06-08-2008, 07:13 PM
#27
Umm, not quite. If it weren't performing a function, it wouldn't turn on. Power to the fan would simply be cut when you turn the ignition off. And whoever said that it doesn't do anything since the pump isn't running is wrong too. The running fan is, in fact, performing a cooling function. Turn it off at your own risk.
06-08-2008, 07:17 PM
#28
Umm, not quite. If it weren't performing a function, it wouldn't turn on. Power to the fan would simply be cut when you turn the ignition off. And whoever said that it doesn't do anything since the pump isn't running is wrong too. The running fan is, in fact, performing a cooling function. Turn it off at your own risk.
06-09-2008, 02:49 PM
#30
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Just because your engine isn't pumping water doesn't mean that you wont get some amount of circulation due to convection. Furthermore creating a temperature differential in the radiator will lower core temperatures as the entire cooling system will always seek thermal equilibrium. It just won't happen as fast as if the water was circulating.
Engineers put a lot of thought into designing this engine, and even then many of their systems seem to underestimate the demands of the engine. If the engineers thought the cooling fans were required after the engine is shut off, do you really want to risk shutting them off, knowing their penchant for under-engineering things rather then over-engineering them? If anything I'd want to mod them to come on earlier and stay on longer.
Engineers put a lot of thought into designing this engine, and even then many of their systems seem to underestimate the demands of the engine. If the engineers thought the cooling fans were required after the engine is shut off, do you really want to risk shutting them off, knowing their penchant for under-engineering things rather then over-engineering them? If anything I'd want to mod them to come on earlier and stay on longer.
06-09-2008, 04:39 PM
#31
perhaps you are too young to remember that once upon a time the fan was direct drive off the front of the motor . All the manufacturers must have changed to electric to stop them all overheating while not running
Seriously though lets think about why Mazda may have designed the system this way - I believe it could be to aid in certain situations when an engine is turned off for only a few minutes - ie going into the store to pick up the paper . In that situation there would be some benefit in leaving the fans on so that any heat soak in the engine will be rapidly cooled by the cooler radiator water upon restarting .
Anybody else have any decent suggestion other than the "Mazda did it that way so it must be right" BS ?
Seriously though lets think about why Mazda may have designed the system this way - I believe it could be to aid in certain situations when an engine is turned off for only a few minutes - ie going into the store to pick up the paper . In that situation there would be some benefit in leaving the fans on so that any heat soak in the engine will be rapidly cooled by the cooler radiator water upon restarting .
Anybody else have any decent suggestion other than the "Mazda did it that way so it must be right" BS ?
Last edited by Brettus; 06-10-2008 at 12:03 AM.
06-10-2008, 08:39 AM
#34
Oh you flatterer, I'm well old enough to have changed fan belts (when they were really fan belts).
Not so applicable to our [present] 8's, but there is some fuel injector vapor-lock prevention advantage to continuing to flow cooling air around the engine compartment after engine shut down on very warm days.
Otherwise as you cite, and I stand corrected in that you appear far from ignorant on the subject.
Not so applicable to our [present] 8's, but there is some fuel injector vapor-lock prevention advantage to continuing to flow cooling air around the engine compartment after engine shut down on very warm days.
Otherwise as you cite, and I stand corrected in that you appear far from ignorant on the subject.
perhaps you are too young to remember that once upon a time the fan was direct drive off the front of the motor . All the manufacturers must have changed to electric to stop them all overheating while not running
Seriously though lets think about why Mazda may have designed the system this way - I believe it could be to aid in certain situations when an engine is turned off for only a few minutes - ie going into the store to pick up the paper . In that situation there would be some benefit in leaving the fans on so that any heat soak in the engine will be rapidly cooled by the cooler radiator water upon restarting .
Anybody else have any decent suggestion other than the "Mazda did it that way so it must be right" BS ?
Seriously though lets think about why Mazda may have designed the system this way - I believe it could be to aid in certain situations when an engine is turned off for only a few minutes - ie going into the store to pick up the paper . In that situation there would be some benefit in leaving the fans on so that any heat soak in the engine will be rapidly cooled by the cooler radiator water upon restarting .
Anybody else have any decent suggestion other than the "Mazda did it that way so it must be right" BS ?
Last edited by Huey52; 06-10-2008 at 08:53 AM.
!
06-10-2008, 11:39 AM
#36
Fan run-on time can be decreased if you turn off the A/C at least four minutes before you turn off the car. Keep the cabin fan running, but shut off the compressor with the A/C button. This alone will let the engine cool enough before shutdown to trim a few minutes off the time.
06-10-2008, 12:14 PM
#38
Or you can turn your heat up full on a hot day JT. 
Ol' days (pre-auto computers) we used to pride ourselves on being able to limp home regardless the malady. I've actually used the heater to offset overheating for a short duration.
Keep in mind that there's no such thing as cold - only an absense of heat. Think moving heat from one place to another. That's all a/c and radiators really do.
Ol' days (pre-auto computers) we used to pride ourselves on being able to limp home regardless the malady. I've actually used the heater to offset overheating for a short duration.
Keep in mind that there's no such thing as cold - only an absense of heat. Think moving heat from one place to another. That's all a/c and radiators really do.
Fan run-on time can be decreased if you turn off the A/C at least four minutes before you turn off the car. Keep the cabin fan running, but shut off the compressor with the A/C button. This alone will let the engine cool enough before shutdown to trim a few minutes off the time.
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