Alternator Belt Flopping Around?

[tbryanh]

The alternator belt on my 6.9 flops around alot when the engine is running. There is a long distance between the alternator pulley and the crankshaft pully, and this is where it is very noticeable.

The belt does not squeal, and I tightened it as tight as seems reasonable, but it still flops around. I do not want to overtighten it and wear out the alternator bearing or cause the belt to jump off the pulley.

Is this normal, or should I change the belt?

 

[riotwarrior]

Normal...

 

[79jasper]

I think the belt sorta gets "caught" in the v-grove, in turn causing the flop.

You should stand near a pump jack watching the belts. Some are bad enough to make you wanna hide behind a tree or something.

 

[ZWilson07]

Like stated its normal.

Im actually just picking up a shorter belt to run from my ALT to WP, vs ALT, WP, and CS even if it is "normal" I still don't like it; when I get the part number or length ill post it up.

Seems like this question has been asked alot here, especially lately; myself included lol

 

[91idi]

My 91's belt never really did. Then the alternator dies. The new alternator has a bent shaft. That's why mine jumps

 

[idiabuse]

Use the gates green stripe belt for the alt and dont make it tight, it needs to flop around a bit. the green stripe will take the abuse years longer than economy belts.
I used to know the part number but the sharpie mark wore away under my hood


Javier

 

[icanfixall]

Quality belts are less **** to flopping around. Running the shorter belt off the water pump works well too. Some have posted the belt flop was due to the vacuum pump actions but I never was able to prove or disprove that thought. Some have installed custom idler pulleys on the floppy side run of the belt too. This is somethimes worse on some trucks and not very noticable on others... No real rime or reason for this issue..

 

[Jake_IN]

Mine does it too and it use to bother me some. Then i discovered that as soon as i take the engine off idle the flop completely goes away and it runs smooth. So i figured beings that when my truck is running, im usually driving somewhere, the engine isn't really idling. So i just dont worry about it anymore.

 

[bbjordan]

That is one of reasons I upgraded to the serpentine belt system.

 

[Mulochico]

Some have posted the belt flop was due to the vacuum pump actions but I never was able to prove or disprove that thought.

I disconnected the vacuum pump awhile back for a test and it did make a difference.

 

[HammerDown]

I've been running the "short belt" for years and years

 

[icanfixall]

The short belt works for lots of owners. I personally never had an issue with the dreded belt flop when I ran the V belts.. Now with the serpentine system I have no worries...

 

[Black dawg]

Use the gates green stripe belt for the alt and dont make it tight, it needs to flop around a bit. the green stripe will take the abuse years longer than economy belts.
I used to know the part number but the sharpie mark wore away under my hood


Javier

Years ago, I had trouble with alt belts, it seemed like I would find something wrong with them at avery oil change. I tried adding idlers, and while it did keep the belt from flapping, they still wore out really quick.

I went to this green stripe belt, and no problems for probably 100k or better.

 

[blakpete91]

It flops around because of the vacuum pump. Since the pump oscillates when it compresses the belt vibrates accordingly. I researched it a while back when I didn't know if it was normal or not but it is normal.