Cooling rebuild advice

[Gordie Allen]

I have a 4104 I bought in Feb. this year.  The previous owner replaced the radiator and fan/hub assembly after his original fan disintegrated and took out the stock radiator about 6 yrs. ago.  Unfortunately he replaced the stock one with an over-sized truck radiator that just doesn't fit and hangs down so low it's just a matter of time before it bottoms out and breaks.  The bus has a 4 valve 671 with 15000 mi. since out of frame rebuild.  It runs great.  While driving the bus from Florida to Michigan after purchase, the replacement fan failed.  This was a $1500 bolted flange hub with plastic blades.  All the blades broke off at the flange.  Fortunately he had installed an expanded metal guard over the radiator, so it survived.  I rigged two electric fans from Autozone to get her from Atlanta to Michigan.  Cold weather helped.  So I have removed the over-sized radiator and am looking for one that actually fits.  After reading posts in the Archives I noted that fan failure is not uncommon.  My plan is to put in a new radiator, build or buy a shroud, and fabricate a parallel belt driven fan.  Two belt pulley from engine to shaft mounted in two pillow blocks.  A second set of two pulleys on this shaft would return belts back to the fan located at the front of the engine set.  I'm also considering a 1.5:1 ratio in the pulley system to spin the fan at around 3000+ rpm - to move more air.  In a previous post someone recommended replacing the harmonic balancer, but I'm inclined to believe imbalance in the fan/hub is a more likely cause for failure than imbalance in harmonic.  Any opinions?  (I know there are plenty out there).  Anyone done this?  Seen it? or have any constructive critique?
Thanks,
Gordie

[luvrbus]

If the engine was rebuilt out of frame and the harmonic balancer wasn't replaced your 6L71 will throw every thing off the front of the engine those are one time use balancers if it has any bent places on it you need to toss it YMMD

Just trying to give you a little advice 600 bucks is cheap compared to a broken crank and that will happen if the harmonic balancer wasn't replaced at rebuild

[Gordie Allen]

Advice taken.  I agree this is not an area to be cheap.  Do they still make new ones?   Where do I get one?  Would Luke have something like this?  I'm already ordering radius rod bushings from him.  Might as well throw in the harmonic balancer.
Thanks for the advice.  I think you told me this before.  Slow learner sometimes.
Gordie

[luvrbus]

You can buy a aftermarket from outfits like PC Industries or Diesel Pro for about 300 bucks a genuine DD will be around 600 bucks replace the seal ,sleeve and cone while you have it off  

I just checked PC Industries the aftermarkets are now 500 bucks for the 12 inch and 1200+ for the 15 inch dia ouch hope you don't have the 15 in one lol the one for the cam is over 300 bucks now

good luck