Belt squeal after alt change?

[Jordanlogo]

Just changed my alt and now upon start up there’s a loud squeal then all of a sudden it goes away. Any way to fix this?

[1986F150Six]

Does the new alternator have a new pulley? Is the belt tension correct? Is the belt new? Is it possible that the battery is not fully charged?

[Gary Lewis]

Yes, I second David's questions.

And, is the alternator just a replacement 1G?  Hooked up exactly the same?  And the same regulator?

I ask because your symptoms are normal with a 3G w/o the delayed start regulator.  But I wouldn't expect that from a 1G as they don't put out enough at idle to slip a properly-tightened belt.  Or at least I wouldn't have thought so.

[CRittaler]

I would suspect that the belt isn't quite tight enough, that's assuming you had a stock alternator and replaced it with a stock alternator.

[Jordanlogo]

1986F150Six wrote

Does the new alternator have a new pulley? Is the belt tension correct? Is the belt new? Is it possible that the battery is not fully charged?

The new alternator has the old pulley. How can I check the belt tension? Should it be super tight?

[Rusty_S85]

Rule of thumb I use is you should not be able to turn the alternator pulley.  If you can turn it then the belt is too loose and will slip.

[Gary Lewis]

Turn it with what?  Your hand?  A wrench?  

[Rusty_S85]

Gary Lewis wrote

Turn it with what?  Your hand?  A wrench?  

Your hand.  Put your thumb on the fan blade of the alternator and try and push.  If it doesnt move I then use a wrench on the nut and try to rock it and see if it tries to rock the crank itself.

Typically if you cant turn it by hand its tight enough I noticed.  With the 3G I am going to use the rock method with a 3/8 ratchet on the alternator pulley to tension the belt tight enough that it tries to turn the engine.

[Jordanlogo]

I just don’t get how to make it any tighter. I’m pushing the alt as hard as possible and it still is kinda loose. How do you get enough leverage?

[CRittaler]

when I did mine, I pried between the alternator and the engine block, from underneath with a pry bar.  I'll try and get some pictures tonight when I can work on the truck

[Rusty_S85]

CRittaler wrote

when I did mine, I pried between the alternator and the engine block, from underneath with a pry bar.  I'll try and get some pictures tonight when I can work on the truck

Ive done it that way before, ive also placed a wrench on the ear of the alternator and pried that way as well.

I cant wait to see how easy it will be with the modified OE alternator bracket without the air pump mounted.  Think it might be possible to tension it from under the hood.

[Vic Roma]

The Haynes manual helped me when I swapped out my lightly fried 2G for a 3G. Use tongue-and-groove (aka channel lock) pliers:

[red1980F150]

That's a good idea.  

I must have a 1G on mine.  I just put it back on last weekend with the ol' hand torque-o-meter and it's fine.  I stuck my hand between the alt. and the engine block and put as much pressure as I could and tightened the top (non-sliding) bolt to snug it in place.  But this method was just from the "I'm making something up" book.  

[Vic Roma]

In my experience, tighten the bottom bolt first, then the top. Beware there is a sweet spot, I tightened the pliers too much and the belt squeaks on start up, have to loosen it up a tad.

[ArdWrknTrk]

Chris, this is my go to method as well.  
And a good reason I threaded the ear on my 3G 3/8-16, so I can use a ratcheting 9/16 to clamp the quadrant while I hold tension on the pry bar with my other hand.

[fr0bert]

Hey Vic, curious what haynes manual you have?? That's a handy diagram but it's definitely not present in my copy of the 80-96 haynes manual.



Just curious if there's a more specific book for earlier bullnoses.

[Vic Roma]

You need the old red cover version, number 880. This page has all the information you need to find it:

https://www.supermotors.net/registry/media/449785

[Jordanlogo]

Got it!

Pry bar on the bottom then the top was the key! Squealing gone, and now I can start Clifford up without waiting for people next to me to pass

[Gary Lewis]