Overheating problems - trying to make my way up I-80 towards Reno

[MC8Mike]

Yeah I vote backwards too, they need to be swapped left to right.

[Jim Blackwood]

Squirrel cage fans will always blow air out the outlet regardless due to centrifugal force. What looks right isn't always right. You have 4 possible configurations: Rotation towards the outlet, rotation away from the outlet, fins angled towards the outlet, and fins angled away from the outlet. All four will blow air out the outlet. The sound or noise will change and the volume of air will change, as will the load on the motor. It's not good enough to just say "It looks right" because sometimes that is correct and sometimes it isn't.

Now I do agree that it "Looks" like it'd blow more air if they were reversed. But you need to be sure, and I have seen fans that will blow more air the other way. I don't know how, I'm not a fan Engineer. But am I wrong in thinking that it is not a trivial exercise to switch the fans?

Jim

[Utahclaimjumper]

It would be easy to get off the computer and start the engine to determine which way the most air is blowing by placing your hand at different points around the cage ..>>>Dan

[daveola]

Yup - the blades travel 'down' as far as the image is concerned.

And yes, I thought that would mean they would reverse air direction (and push air out the radiators) but actually they don't, it just means that the blades aren't 'scooping' air, but going backwards and the curve is what is hitting the air.

So they are definitely backwards, I verified that when I started it up and realized the scoops weren't doing anything.

The trick to fan direction is to realize it's the inside of the blade that is catching air:

https://www.youtube.com/watch?v=OTNzd2dE2Oo#t=126

[dtcerrato]

Yes Sir! your squirrel cage blades are in fact mounted backwards - great find, easy fix, but a very huge risk as far as overheating the engine...

[belfert]

I once took my snowblower to a mechanic as I couldn't get a broken shear bolt out of the auger shaft.  It didn't blow snow worth a crap after that.  I took it apart numerous times and replaced the belt at least once or twice.  I took it to another mechanic who found the problem after two years of the thing barely working.

The original mechanic had reversed the augers from side to side!  It was pushing snow away from the center impeller instead of towards the impeller.  Mechanics sometimes make mistakes.

[Busted Knuckle]

Mechanics sometimes make mistakes.

What?
Well I never have, oh wait a minute that's not true.
Once I thought I was wrong but it turned out I was MISTAKEN!
  BK 

[buswarrior]

This is going to be a nasty job, the fan assembly is awkward, heavy and a very snug fit to drag out of there.

Is the offending party available to do pennance?

Happy coaching!
Buswarrior

[windtrader]

His pain is one most of us feel - lack of qualified and skilled mechanics to work on our old buses. From his original post it seems two places have had their hands in creating and failing to resolve the issues. The first mechanic put it in improperly and the second failed to determine it was put in backward and probably did unnecessary work.

[dtcerrato]

So according to the post on the other board... I'm guessing we need to replace all the humans with perfect robots that never make mistakes! Lol

[Dave5Cs]

Just went out and looked at our MCI and yours are backward.
I took ours out years ago and the way I did it was to disconnect the four bolts that hold it in after taking off the belt and then opening the lower doors and setting two 2x10 across it. I then worked it out to the 2x's and then down a ramp to a metal table that the other end was on where I could work on it. 

[luvrbus]

Just went out and looked at our MCI and yours are backward.

I guess the guy got confused if right or left was from front or the rear those have a R&L in the parts number stamped on the blowers,not a easy job changing those the whole unit has to be removed 

[RJ]

Yup - the blades travel 'down' as far as the image is concerned.

Dave -

My apologies. From first glance, they looked correct. But when you made the above observation, I now agree with the others, that they're bassackwards.

It is a PITA to get the squirrel cage assembly out of the coach, but it's the only way to work on  them.  Here's hoping Bob comes thru for you!

FWIW & HTH. . .

[Jim Blackwood]

Once again, grain of salt. Two things. Your video says the outside end of the blade should point in the direction of rotation. I don't know what that is in you photo but presumably you do.

Second thing. Not all squirrel cage blowers work that way. Depends on how the manufacturer designed it. Based on the video one would think this design is to maintain an engineered static duct pressure and may sacrifice flow to do that. The surest way to check would be to try it both ways and use instrumentation of some at least rudimentary type to see which gives the highest rate of flow. If you are set on reversing them it wouldn't take much to set that up before you start for a before and after comparison.

But so far you have no definitive answer. Just opinions, based on zero actual engineering or manufacturing history. I'd want more before starting in on what sounds like a BIG JOB.

Jim

[dtcerrato]

What Jim said! What would it take to unbelt the squirrel cage and spin it in both directions while it's in the bus?
Contrary to the 1st two sentences above was Dave's post confirming reverse blade orientation in comparison to his similar MCI set up! Soooo where do you go from here? I personally would try & spin them in place in both directions just to compare the difference if it's such a big job to R&R just for certainty & insurance.. IMO