Triumphrat

Aceman_831

exactly what the title says, my cooling fan would sometimes run very long after i turn off the bike and take the key out. I know it is supposed to run for a while but this was very strange, i was nervous because i didnt want my battery to die (i had just put a new one in which fixed my electrical problems lol).

Is there a way to adjust how long the fan runs??

mzavala11

Try this, after you shut off bike, turn ignition key like your going to start bike. On my 02 955i fan shuts off and does not restart

DEcosse

Define 'very long'
It is not so much a time factor as a temp factor - coolant needs to reach the cut-off temp which would be 97 deg C on your bike.
You can adjust that temp, but needs Tuneboy to do it.

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T'Rat.net BOTM November 2009

pumpman

It has always seemd odd to me that the fans would stay on when the engine is shut off, even if it is hot...the air blowing across the motor is heated by the radiator and the coolant is not circulating, so all you are doing is cooling the radiator. Is it just to reduce the chance for a boilover?

bradtx

pumpman, The first statement of the 2nd law of thermodynamics, coolant will travel from the hotter engine to the cooler radiator.

On one of my Mustangs I have has an electric fan back up controller that measures the radiator's temperature. Coolant can transfer from the engine to the radiator for thirty minutes. Each time the fan starts it can restart the cycle.

Brad

pumpman

Brad: If the coolant could travel, it would, but it can't without going thru the coolant pump. The only heat transfer, absent convection (flow), is conduction, and that would be painfully slow through the stagnant coolant. The temperature differential between engine and radiator(the driving force for heat transfer), is very small when the engine is first shut off, and increases only as long as the fan blows, so not much heat is going to be conducted. When the fan stops, at normal operating temp, the temps will finally equalize, but it takes a while. True, if the engine was hot enough, the fan could come back on as the radiator reheats from the engine heat, and start the cycle again, but a bike engine will cool from normal covection of air around the engine before that would happen. A big V-8 is another story. The fan helps, but not enough to justify the big battery drain on a bike. But I could be wrong, as often I am.

pumpman

(crickets chirping)

bradtx

pumpman, I tried to find, but have failed, something that illustrates my point. Maybe better wording is that the heat energy, along with some coolant transfer passes from the hotter engine to the cooler radiator.

From my understanding, this energy transfer will continue, in this case, until the pressure within the entire cooling system equalizes with the ambient air pressure, indicating there is no more heat energy to transfer. (The pressure has nothing to do with the heat energy transfer, it's just a byproduct.)

Brad

pumpman

Brad: You provide a tremendous amount of solid, insightful, useful information on this site, and I am grateful for it. You always jump in when someone has a question, and many, including me, have been helped by your wisdom and experience. Your instincts are spot on, keep it coming.

bradtx

Thanks for the comments, pumpman. The strength of the forum is all of the member's input and perhaps more so, some of the more interesting questions.

If the internet were around when I had my Z1 I surely wouldn't have made so many mistakes with it.

Brad