Alternator belt slap? 1991 F250 4x4

[noddaz]

strange thing. The part of the belt between the alternator and the crank pulley really flops back and forth while the engine is running. The belt seems tight deflection wise. Is it as simple as tightening the belt further?
Thanks..
Scott

 

[TronDD]

That seems to be the way it is. The belt is too long. Lots of folks replace it with a shorter one that goes around the water pump pulley and alt only. The part number is somewhere on here if you search.

Tim.

 

[idi_econoline]

I've read on here that over 95 amps, the alternator needs a second belt..... can't imagine TWO belts slapping away on that long side!

 

[noddaz]

That seems to be the way it is. The belt is too long. Lots of folks replace it with a shorter one that goes around the water pump pulley and alt only. The part number is somewhere on here if you search.

Tim.

Interesting....... And Hmmm. If (when) the new belt goes bad I might do this...
Thanks.

Scott

 

[rattleonby]

Every hood i popped on a v-belt idi has done this. It will slap no matter how tight ya make it. Doesnt hurt anything or make a difference. My alt belt is as tight as you should have it and it flops away, but when you shut it off and go to feel the belt its nice n tight.

 

[fellro86]

Usually hasn't been an issue, however I have had them jump and twist going down the interstate. Thankfully, it was during business hours for a local parts store and was bale to get the a/c belt on good enough to spin the water pump to drive on in the 20 miles to a parts store. I have put an idler pulley on the return side to help a little. We will see how it works out, as it is a flat pulley from a dryer...

 

[noddaz]

Usually hasn't been an issue, however I have had them jump and twist going down the interstate. Thankfully, it was during business hours for a local parts store and was bale to get the a/c belt on good enough to spin the water pump to drive on in the 20 miles to a parts store. I have put an idler pulley on the return side to help a little. We will see how it works out, as it is a flat pulley from a dryer...

Interesting.. Any pictures of how you did this?
Scott

 

[Alan Slingsby]

Both my idi's 85 & 86 also jump around like crazy but they are tight,just on the alternator tho

 

[fellro86]

No pics, but the truck is sitting 10 ft from me... I will have to get one. Pretty clear view. Funny thing is, now it does the jumping on the top side, just not quite as bad.

 

[bbjordan]

Ya, that belt flapping around bugs me. That's why i switched to the serpentine belt system on my '86. It worked well with the 3G alternator upgrade too. The vacuum pump takes a little longer to swap out, but its a very small penalty to pay for what I would say is a better system. But ya, that's normal. The belt flops around, even when the alternator is frighteningly tight!

 

[fellro86]

This is how i mounted it. I unfortunately don't have any road time on it, but as long as the bearing holds up, it seems to work fine.

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[icanfixall]

Alternater belt flop is one of the best reasons to replace the v belts with the serpentine belt system. Well that and the alternater belt is the first belt on the engine to go bad and you need to remove all the belts to get at that one problem belt... Not so with serpentine... Just one simple to install and no adjustments to make. Install and run the hell out of it. I have a complete serpentine belt pulley kit here. I made it up as a spare but have had it for 6 years.. No need to keep it longer.. Had it listed in the market place. Hate to say it but its a great deal and simple to install. Its a no brainer modification. PM me for interests..

 

[vegas39]

Mine flop too, never had one fly off yet.
No way would I ever convert to a serpentine system. If an uneeded component fails, I want to be able to cut the belt and run. I've seen more than one serpentine system lock up an a/c clutch and be left stranded in the middle of the desert. If they had v belts, they could have been back on the road in a couple of minutes.

 

[HammerDown]

Within 500 miles driving my truck NEW off the dealers lot (1988) the floppy alt belt broke and took all the rest with it...had no brakes, pwr steering and the trany wouldn't shift because the vacuum belt also went.
Over the years the above happened three more times!

Fock that long belt, many years ago someone here mentioned using a much shorter belt and I've been using it ever since...works great!

 

[icanfixall]

Kenny while I do agree with you being able to cut off a v belt and keep running the problem still is there with the long floppy alternater belt. I just have had to repalce that belt one time tooo many so I changed to the serpentine belts. I have had no issues with that system and many thousand miles have been run with it now. Of course when it fails I will be stopped but hopefully I wont be stuck with an alternater bearing or an ac compresser bearing froze up. I do carry a complete serpentine belt, vacuum pump and pulley with the tensioner and idler and tools to install. Have not needed any of this in 7 years.. But I have the satisfaction and comfort of knowing its there like cost free insurance..