Electric Fan or hydraulic motor

[prevost82]

I would put a Horten air hub on it. You maybe fine on the flat but what about a hot day (95+) running up a 6 to 7% grade for 12 to 16 miles. You may need all the cooling you've got. Adding hydraulics just adds to the complexity to your cooling system.
Ron

[NewbeeMC9]

http://www.hi-lo.com/pages/products12-99.html  they claim to have these up to 125 hp

or here,  some body here could tell you what hp,  i guess 20 or 30

http://www.speedselector.com/fixer.htm

I'm sure hydraulic's would be cool.  

However, i vote for changing pulley size as simplist, easiest, cheapest, and most reliable.  maybe not bigggest savings but the savings/effort ratio would be up there.

DIYW

let us know what you come up with.

[Busted Knuckle]

I'd have to agree with the Horten (or other brands) air or electric clutch set up! The Horten should be the easiest as they are common on big trucks already and should be easy to get one for your application at either a truck dealer or truck parts supply house! This way you can have it set to come on by thermostat or a manual over ride switch! JMHO FWIW!    BK 

[TomC]

Brian- I have an 8 blade 30" aluminum fan with a 3" pitch that runs all the time.  On cool days, the temp stays right at 175 degrees.  Then climbing it will get to 185.  Above that I kick on the misters.  But the fan is running all the time.  It is better to have the engine at a constant temp than to have it climb up and down sometimes close to 20 degrees with the themostatically operated shutters.  If your engine is not getting up to at least 175 degrees with a 180 thermostat, then a replacement is needed.  I would suggest you run the bus as is for a few more thousand miles to get the rhythm of the bus.  No need to worry about this to much now!  Good Luck, TomC

[Brian Diehl]

Thanks everyone for all the ideas and feedback.  I have replaced the thermostat.  What I've learned so far is if I keep the front heater core valve open the engine never comes up fully to temperature.  If I shut the heatercore valve off it will come up to temp fairly quickly.  I have not yet experimented with how much I can open the heatercore valve and still keep it up to temperature.

I think for now I'll simply experiment with restricting the amount of air moved by the blowers.  Then, as was suggested, put a bunch of miles on to make sure I know how it handles high temperatures and long grades.  After I'm comfortable with how it responds then I'll look at a clutch based system or better yet a variable speed system.  *Ideally* I'd be able to have a two speed system.  Slow for when I just need air flowing through the CAC and high for when I'm climbing that long grade!