OK tech heads, look alive here's a hypothetical one for ya.
I enjoyed a beautiful drive last Sunday in the ol' Rebel, tops off, sunshine and had a fantastic time (except that I got burned - doesn't matter!!!)
Anyway, on the way home I pulled in to visit the pres who was hard at work, switched the engine off and the thermo fans are still going at full speed.
"Hmmm, I've never noticed that before" - me thinks
"sometimes they do that until the engine cools" - the pres.
"I'll buy that" - me again.
15 minutes later.....
"I don't think it's supposed to do that mate" - the pres
"geez I hope 10 volts is enough to kick the engine - I'll check it at home" - first go, she fires sounds fantastic and we drive home.
I pop the bonnet ... fans still roaring ..... the water resevoir's lid is off, tubes in the air and of course no water/coolant flow. I jump across the other side, pull the plug at the fuse to stop the fans, top up the resevoir, close the lid and carefully open the radiator cap. Water refluxes as expected through the bottle and out the over flow.
I check the voltages at the relay to find it's reset. I reconnect the fans, start the motor and no fans (temps have now dropped). I wait a few minutes, temp climbs and fans are back again as normal.
So what happend .... ? My best guess is that the cap came off the resevoir well before my trip began causing an air lock at the radiator. The motor was never at risk as the water still flowed through the radiator, top hose and back through the lower one. The thermostat kept measuring high temps and hence the fans stayed on to cool the water in the radiator.
:P
Or maybe the switch just got stuck .... ? ;-)
Theories ->
