Chevy 454 fanbelt keeps jumping off?

Hip · Feb 19, 2012

this is an 82 454 in my motorhome. when i bought it the fan belt was squeeling a little. week later it bailed. bought a new one and discovered two spares in the motorhome parts bin?? replace it squeel went away mostly.

lasted a week. 100 miles went bye bye....replaced alternater.

looked real close and discovered the pullys weren't exactly lined up so i shimmed the ALT pulley to match the vehicle.

this belt lasted almost 1500 miles....went off on the hiway.

pulled over and changed to a spare. lasted 50 miles.

next and last spare went on and lasted ten miles.???

all belts were new and tight? All squeeled right away?

this rig has the 100 amp alternater in it.

what else can i do?

anyone have a serpentine setup for sale or trade?:redneck:

skinny_pedal · Feb 19, 2012

Does it also connect to the airpump?

rchrd989 · Feb 19, 2012

It's a long shot but it could be play in the main bearings, causing the crank to thrust in and out.

JOOP · Feb 19, 2012

somewhere a pulley is not lined up or the bearings are bad causing it to wonder. Then it flies off.

pokey · Feb 19, 2012

wrong pitch on one of the pullys thats not allowing the belt to fit down in the groove right.

PORTER · Feb 19, 2012

I would check to make sure the belt is in proper alignment. Had this happen before.

Hip · Feb 19, 2012

skinny_pedal said:
Does it also connect to the airpump?

no air pump.

rchrd989 said:
It's a long shot but it could be play in the main bearings, causing the crank to thrust in and out.

can chack i guess but oil pressure is high and steady.

JOOP said:
somewhere a pulley is not lined up or the bearings are bad causing it to wonder. Then it flies off.

i didnt remove the other belt and check waterpump bearings but the pulley is aligned perfect. i'll remove other belt to verify.

pokey said:
wrong pitch on one of the pullys thats not allowing the belt to fit down in the groove right.

i think the pitch is right but there is a little minor (very minor) rust damage from where it sat at one time. i seen i lot worse not be an issue. ill polish that off.

PORTER said:
I would check to make sure the belt is in proper alignment. Had this happen before.

see answer to Joop.

thanks guys all good ideas past the basic.:awesomework:

zukkev · Feb 19, 2012

It's gonna take ALOT of thrust play to throw a belt...another thing to think about, just because the spare belts you found in the MH are new, doesn't mean they aren't rotten from sitting forever...the squealing thing tells me the belts aren't getting tight enough, or it's at the max adjustment---not allowing the belt to get tight enough (wrong belt)...these things can be a bitch to get the belt tight even if it's the right one! Good luck!!! :redneck:

Hip · Feb 19, 2012

zukkev said:
It's gonna take ALOT of thrust play to throw a belt...another thing to think about, just because the spare belts you found in the MH are new, doesn't mean they aren't rotten from sitting forever...the squealing thing tells me the belts aren't getting tight enough, or it's at the max adjustment---not allowing the belt to get tight enough (wrong belt)...these things can be a bitch to get the belt tight even if it's the right one! Good luck!!! :redneck:

i agree its a bit difficult but the belts were new and tight.:fawkdancesmiley:

im really thinking serpentine if i can find it. powersteering pump, waterpump, alt and crank. not much to it. no ac, air pump or anything.

do they even make serpentine for 454's, im not a chevy guy but it sure seeme like i should be.....all the chevy crap i now own.:haha:

kokomo · Feb 19, 2012

check the pullys make sure there is not an inward bend in them to allow belt to climb out and throw itself at high rpm's. had a 350 crank pully that had small inward bend that didn't notice right away kept throwin belts too.

Ty. · Feb 19, 2012

I had the same issues with the 454 in my motor home. I kept going through belts. I changed the alternator, and the water pump. I'm pretty sure it was the water pump that healed it up, but I can't say for sure. Can't remember for sure.

The wife thinks it was the water pump.

Jacob · Feb 19, 2012

My dad had a 396 that would throw off and chew up belts and it was his fan clutch that was causing it.

nowires · Feb 19, 2012

A Pulley is bent or out of round. Causes a harmonic in the belt that throws it

bobbed_84_toy · Feb 20, 2012

I had a harmonic balancer crack on me once, it would move around enough to chuck the belt. Did you spin everything that belt drives by hand to make sure nothing is locked/locking up?

t1h5ta3 · Feb 20, 2012

does the belt sit in the grove, flush, or above the grove?
with the belt off, spin the water pump pulley. check for run out, out of round and for the grove width changing.
look at the old belt, is the wear on it even? does it twist up if you set it down like it has broken cords?

yes you can get serp setups for bbc.
you can get fancy billet ones or plain steal ones.
http://www.alangrovecomponents.com/Catalog.htm
or even stock oem serp setups..

Corey Y · Feb 20, 2012

1985+ truck 454s have a factory serpentine alt. belt and dual PS v-belts. I see alot of tossed Chev PS belts at the mudbogs.

Poohbair · Feb 20, 2012

http://www.marchperf.com/gallery_chevybig.html

CHOP SHOP · Feb 20, 2012

stop buying belt at vatozone or shmucks.

either you have a chunky rotator or a bent pulley or a missalignment issue.

I would look at the alternator and make sure its (not shimmed out but square) square to the other pulleys. Alt brackets on chevys tend to let the alt tip in a bit. Take a two foot chunk of straight flatbar or a metal ruler and place it across the pulleys and see if any are "tipped".
If all checks out and it still spits, then I head to the tractor shop and get a green AG belt and tighten the **** out of it.

Belts are real simple. Remember how wobbly that crappy ol riding lawn mower belt is and it stays on in a horizontal position too.

I wouldnt worry about crank endplay. I have a motor in my jetboat that has .13 thou of end thrust. It will visibly shock ya when it moves and is easy to see. It came out of my old crewcab that I drove for years and never shot off a belt.

Hip · Feb 25, 2012

pokey said:
wrong pitch on one of the pullys thats not allowing the belt to fit down in the groove right.

"winner"

the original belt and the spares were all too thin, i tried a 1/16th wider belt and even though it seems too fat it is staying on so far. the other belts the center was barely touching causing the sides of the belt to loose grip

pokey · Feb 25, 2012

Hip said:
"winner"

the original belt and the spares were all too thin, i tried a 1/16th wider belt and even though it seems too fat it is staying on so far. the other belts the center was barely touching causing the sides of the belt to loose grip

Glad I could help Hip and you dont even owe me a cookie :haha: