MCI 5C Belted Alternator Failure

[Gary '79 5C]

Back from a week trip to SC & NC. But on the return trip, we lost the alternator drive belts, which also took out the oil line to the stock alternator. EZ outed the remaining oil line fitting from the block, plugged and limped home on the start batts. Headlites looked almost like candles pulling in.

BUT, My question is that this is the second time in 4 years that the pulley sheave on the alternator loosened and wobbled enough to throw the belts, and ruining the splined armature shaft. Yuck.
I need direction on my solution, which I see there are three.

1. I can pick up a replacement from Nimco and reinstall without warranty. Hopefully not repeating the same episode as described above...

2. I can pick up a 24V truck alternator ie 75 - 100 amp would be plenty. I would have to fabricate a bracket to mount the alternator, which I am thinking would bolt up to the existing pivoting cradle.
Bus air has been removed. The alternator charges the start batts & thru a Vanner also charges the house batts. I also have a 2000W inverter which charges the house batts when on GenSet or shore power.

3. I could take the existing alternator, remove the armature/ shaft and have it turned down to about 7/8 inch, cut a keyway, and source a sheeve which matches the original with a taper lock bushing inside to mate to the newly cut 7/8 inch shaft & keyway. Install with proper belts and go.

I am really bummed about this repeat failure, but I did pull the alternator much quicker this time. It is a heavy sucker.

All thoughts much appreciated, Thanks,

Gary

PS I also removed the hot water heater as my beloved wife mentioned (Big Time) of the sulfur something smell. No bottom drain, but washed out nearly 2 inches of crud out thru the element hole. WOW. I doubt it was not drained for 10 - 15 years...

Also spoke to Bob while at Luke's today, very nice person, wonderful to converse.

[NJT 5573]

I would just put a truck alternator on it and forget it. Can you spot weld the pulley on? If you redo the big unit, since it has this problem, I would at least spot weld the nut on the shaft after I pulled it down tight.

[Gary '79 5C]

NJT 5573,

Thanks I am going to check out truck alt's tommorow, Luke put me on to a source. I still do not understand the failure, as MCI has had this design for years ?? I will speak to a NJ bus mechanic as to history. But I think I favor the smaller unit.
Actually. while @ Luke's I noticed Bob of the North's engine has a 8V92 w/ the smaller 24V alternator.

I would be wary of welding on the armature shaft, in fear of blowing the windings. Spot weld might not inflict internal damages. I have seen welders in industry use a three phase motor mounting foot for a ground and the motor failed quickly there after.

I am not looking for the workout to remove this again.

Thanks NJT,

Gary

[roadrunnertex]

Many years ago fellow bus person had a MC-5A had the same thing happen to his alternator.
We removed the old alternator and installed a smaller  Delco Remy 50 amp 24 volt alternator.
Had to fabricate a bracket for belt tension and add a mount to the  old mount for the new alternator.
It worked fine and never had any more problems.
jlv

[NJT 5573]

Gary, I bet you could put on a used 12 volt truck alternator and change to a used 12 volt starter for less than a new 8SC in 24 will cost you. I went thru this a few weeks ago and the cheapest I found the 110-575 Prestolite was $500 at elreg.com in NY. Thats not the right # for you though as it has a full time regulator for my a/c. The 8SC in 12 volt was on the shelf at my rebuilders for $80, but the 24V is somewhat rare. I guess if you still have the  24V A/C-heat blowers though you will need the big unit. I think you are right about the welder! Maybe some Locktite!

[Tenor]

I suffered the same exact problem a few months ago.  The pulley wore out, wiped out the splines on the armature shaft, and because it ran eliptical, it damaged the bearings in the front of the alternator.  I replaced it with a Leece Neville (spelling?) 24v alternator 150amps.  It is run with 2 belts from the crank shaft and is mounted by bolt to the curb side engine cradle on a modified pivot.  I'll get some photos on friday.  I have yet to remove the old alternator, but i bought a second Leece 24v 150amp to attach to the bracketing for the original alternator.  You can run both and they will not interfere with each other.  I wanted 2, since I will be powering a xantrex 4024 inverter.  These are easily available.  If you have 2 and one fails, just keep going!

glenn

[steve5B]

  Gary,

  Great place to get that repaired is B&R auto electric Grove City , Pa.  Ask for Rodney.  814-786-8112

  Steve  5B.......