[CJ7Taz]

So how many big Macks (the truck not the burger) have you seen on the trails and/or making water
crossings?

Explain to me how the clutch fan is going to make that water crossing without disconnecting it. Are you
going to wait on the side of the stream until it gets cool enough to disengage the clutch? Even then, it
will still spin since it's mounted on a rotating shaft and the air doesn't provide enough resistance to stop
it. The water will stop it if the clutch is disengaged, but how quickly. Remember Newton and objects in
motion tend to stay in motion?

As to the shroud, absolutjeep hit on the problem but missed the target with the path of least resistance.
As long as the air goes through the radiator, it doesn't care whether it's through the fan or around the fan.
The problem is that, without the shroud, the edges didn't cool and the coolant takes the path of least
resistance through the hottest part of the radiator. Hotter fluids flow better. Even this wasn't a problem
until the mid '60s muscle car era, when the engines got bigger and the grilles got smaller.

You said you had radiator fan questions, the answer to the second part is use electric for a number of
reasons, but you don't seem to like the answer. As far as the MGB, I doubt the problem is the electric
fan. The biggest problem is the itty bitty grille opening, a problem you don't have with the Jeep. Still,
the electric fan won't make up for dirty radiator (inside or out), bad thermostat, belt slippage on the water
pump, etc., etc.

 

[CJ7Taz]

I'm not trying to be argumentative but I find a few things wrong with your analysis.

Your statement: As far as the water stopping the fan...if it is a thermal clutch, even if the clutch is
engaged, the cold water shocks the clutch and they release rapidly
Half of the fan is already under water by the time the water reaches the clutch to disengage it and the
damage is already done.

Your statements;
the inertia of the fan blades (and the associated forces causing them to stay in motion) is minimal, as it
is directly tied to the minimal weight of the fan itself
and;
whose large area (designed to work with air, not water)
are inconsistent. Even though the latter statement is made about non-clutch fans, the clutch fan still
has the large blades and therefore significant inertia. Have you ever noticed how long a disengaged
clutch fan will freewheel (still moving air) after the engine has stopped?

Depending on the RPM of the fan at the time, the strength of the arms attaching the blades to the hub,
and the distance between the fan and the radiator, less than 2" of the tip of the blade being in contact
with water could cause it do damage to the radiator.