By cooling the radiator it will gradually drop coolant temperature as is dissipates through system.There is no coolant circulating correct so there is still hot coolant through engine but the fan does help to relief the heat starting at the radiator cooler air absorbing the hot,sometimes just turning engine over will help circulate the water.Keep in mind make sure your water/Antifreeze mix are with par .do not add mostly water as it will crack the block if it freezes.the balqnce of mix must be right.A hydrameteter works best.
By rotating the engine your transferring the cooled coolant from the radiator through the engine possibly allowing signal from temp sensor to tell ECM to enable.I am no expert here,only giving you some insight through my experience with my sled and found it was all heat related and these are some of the procedures I have endured to correct the issue,as most of my experience is involved with working on trucks as that is my field of expertise where all basic fundamentals are applied to the same for both.That may be partially true but how long would you have to run the fan and beat on the battery before it transfers enough to cool the block? The battery would be dead before you got the block cool enough to make the sensors read normal temps. I just think people are just coming up with rituals and dances to get the thing to start. Both of ours have an occasional hot start issue but I think it has more to do with luck whether it starts or not than anything else. The only thing I noticed with ours is if the fan kicks on when you key it up, I wait until it stops pushing the hot air towards the air box and 9 out of 10 times it starts. If it doesn't start immediately, I just keep cranking it over until it fires and that is usually with another couple of seconds. Some people use the kill switch to shut it down, some use the key. Some say theirs never has a starting issue, some do. Some say cool the radiator first, some say to just key it up and rotate the engine without letting the fuel pump prime, some say this, some say that. I guess it comes down to whatever variables are present and whatever method you find starts the damn thing up for you. There isn't enough consistency of the issue and resolutions to know exactly why and how.
As far as how long to leave fan on depends.Usually let fan run for few minutes prior to starting,permitting you have a good battery,generally most fans kick on automatically accord to temperature signal from sensor to the ECM.If at all possible hook up a toggle switch and do it manually prior to starting the machine during its heat soaking cycle.By rotating the engine your transferring the cooled coolant from the radiator through the engine possibly allowing signal from temp sensor to tell ECM to enable.I am no expert here,only giving you some insight through my experience with my sled and found it was all heat related and these are some of the procedures I have endured to correct the issue,as most of my experience is involved with working on trucks as that is my field of expertise where all basic fundamentals are applied to the same for both.
By rotating the engine your transferring the cooled coolant from the radiator through the engine possibly allowing signal from temp sensor to tell ECM to enable.I am no expert here,only giving you some insight through my experience with my sled and found it was all heat related and these are some of the procedures I have endured to correct the issue,as most of my experience is involved with working on trucks as that is my field of expertise where all basic fundamentals are applied to the same for both.
normally fuel injected machines.cars,trucks etc. you are not to touch throttle during initial start up as it may flood engine.certain circumstance that rule may differ.My viper can be sitting all night at below 0 temps and when I go to start it if I let the fuel pump cycle completely then try to start it it'll sputter a bit then start. If I don't let the fuel pump cycle and start it right up it fires right away..that is when it's completely cold and not running for along time, same exact thing happens when it's hot, hot or cold it makes no difference on mine.
Hopefully a month from now this will all be a thing of the past and everyone will just be able to turn the key and go.