mci throwing belts

christopher · August 30, 2013, 05:42:14 PM

what causes the belts to flip or come off the pulleys?
Thanks
Chris
MCI5C

luvrbus · August 30, 2013, 05:49:31 PM

Check the belt adjuster if it has a pneumatic adjuster be sure the valve is on

lostagain · August 30, 2013, 05:55:02 PM

The belt has to be the right size for the pulleys: the angle has to match the pulley's, and more importantly, the belt has to ride in the pulley without touching the bottom. Look and make sure the belt does not ride against the bottom of the V in the pulley. The belt has to ride on the sides of the V, off the bottom. If it does, get a bigger belt. A belt the right size for the pulleys will last a long time, and will also tolerate some misalignment.

JC

luvrbus · August 30, 2013, 06:05:16 PM

To add to JC comments be sure it is a automotive belt not a hardware store belt for some type motor to run equipment big difference in the 2 type belts once a belt flips correct the cause then you buy new belts very seldom can you make it stay on after it flips

kyle4501 · August 30, 2013, 06:11:53 PM

Some other thoughts -
Is it a new belt or an old one? If old, it may have some broken cords & needs replacing. If new, then check pulley wear & alignment. Also confirm the idler pulley bearings are in good condition.

luvrbus · August 30, 2013, 06:21:44 PM

Wonder which belts he is throwing the alternator or blower ?

B_K · August 30, 2013, 08:26:21 PM

I've also seen belts flip or come off if the engine cradle somehow loosens up and the whole thing moves causing misalignment. (not something that happens everyday, but I've seen it on several coaches over the yrs!)

BK

wg4t50 · August 31, 2013, 03:05:41 AM

All the above, howsomever, the only belts that consistantly flip over are the Dayco brand, between fliping over or breaking, the Dayco belts have never been a success story for anything I have tried them on. Instead never have had an issue with the Gates brand, same as NAPA brand.
I never had an issue with my origional belt setup on the MC7, so am wondering about alignment and tension ?
Never heard a word about this on a MCI, should be a simple fix, I'm guessing on that.

luvrbus · August 31, 2013, 06:09:55 AM

I have had good luck with the Goodyear belts over the years,I bought a belt from a mill supply one time in Conroe Tx when I lost a blower belt on the 8 it was 1/2 the cost I had paid before and it was worth every penny I could not keep it on the belt was still in the bay when we sold the bus

eagle19952 · August 31, 2013, 07:25:58 AM

this helped immensely when I had this same problem....the tool.
you might even find mis-matched pulleys....

Brent from Gates Product Applications demonstrates how to use a V-belt sheave gauge, a maintenance tool which determines if a belt fits properly in its sheave groove. Learn how to select the proper gauge size for different belt cross sections and how to identify unknown belt cross sections. Contact Gates Product Application with any questions (303)-744-5800 Opt 2.

V-Belt Sheave Gauge - Gates Corporation

luvrbus · August 31, 2013, 07:58:12 AM

Yea you can buy those gauges for 5 bucks a set some parts houses will give you a set along with a belt tension gauge

HB of CJ · August 31, 2013, 02:59:19 PM

Reasons why belts jump off? 1) Wrong size belt. 2) Not specific belt. 3) Wrong grade belt. 4) Worn belt. 5) Loose belt. 6) Over tight belt. (sometimes) 7) Tight but non aligned pulleys.

Loose non aligned pulleys. 9) Worn out tensioner. 10) Sudden RPM shift. 11) Road debris in pulley, 12) Wet belt. 13) Hot belt. 14) Frozen cold belt. 15) Belt vibration caused by bad engineering. 16) Overloaded belt. Wow!! HB of CJ (old coot)

christopher · August 31, 2013, 07:05:11 PM

Thanks for all the replies. My bus has tossed the ac belts and blower belts. Ill do some checking and see what the deal is. I have a feeling its mialignment.
Thanks
Chris
MCI5C

eagle19952 · August 31, 2013, 07:34:31 PM

Quote from: christopher on August 31, 2013, 07:05:11 PM
Thanks for all the replies. My bus has tossed the ac belts and blower belts. Ill do some checking and see what the deal is. I have a feeling its mialignment.
ThanksChris
MCI5C

so did I..... it was worn and mismatched pulleys....
ask yourself how would the pulleys get mis-aligned ?
bad bearings...
re-engineered by any other means except FACTORY design....

when did it start...

mine started very soon after I got my coach....turns out someone replaced the fan/alt drive with one not the same as 1979 oem. that one pulley was worn more than all the rest because it got worn out on a different coach....

bevans6 · September 01, 2013, 02:57:18 PM

I would check the obvious - that the crank pulley isn't coming off, that the blower gearbox and AC compressor cranks are good and their pulleys aren't coming off. If one belt came off it could take the others with it. I seem to recall the blower drive belt on the MC-5C is an MCI only part, I got one from Luke. I couldn't get one from my local jobber.

Brian