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Altenator belt issue

B_Dub

B_Dub

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I replaced a squealing altenator belt but after awhile it started again. So I thought the altenator itself may be the cause so I rebuilt it, that helped for a few days.

After staring at my altenator I noticed that it looked like it didn't line up with any of the other pulleys. I thought maybe when the PO replaced the 305 with a 350 crate the alternator wasn't interchangeble so I went out and found one that was a bit taller. It lined up better and all was good...for about a month.

Now the belt is squealing again.

Any suggestions? Thanks
 
The belt is a Dayco. I thought it was an alignment issue. That's what led me to the rebuild and then to the new altenator but still having problem. It seems that I might have a slight wobble at the crank pulley.
 
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Dump question but are you getting the belt tight enough? Also , you may have "glazed" the pulley which would cause the belt to slip, so ive been told.
 
badmix said:
Dump question but are you getting the belt tight enough? Also , you may have "glazed" the pulley which would cause the belt to slip, so ive been told.
Click to expand...


Belt tension is good. I don't glazing would be an issue, yet. I haven't ran it much since it started.
 
I assume its a V belt.
Look at the inside of the belt. The small part of the V.
It should be dry and unworn. If you can see where the pulley has been touching the inside of the belt, then you either have the wrong belt or a worn out pulley.

V belts get their traction from the binding action of the sides of the belt against the sides of the pulley. They should never pull down far enough for the bottom to touch. If it does, you will always have a squeal because there is not enough friction for it to work.
 
Fordum said:
I assume its a V belt.
Look at the inside of the belt. The small part of the V.
It should be dry and unworn. If you can see where the pulley has been touching the inside of the belt, then you either have the wrong belt or a worn out pulley.

V belts get their traction from the binding action of the sides of the belt against the sides of the pulley. They should never pull down far enough for the bottom to touch. If it does, you will always have a squeal because there is not enough friction for it to work.
Click to expand...


Yup, it's a V. I'll check the depth of the belt to see if it comes into contact with the pulley.

I'm assuming its the correct belt for the altenator because I bought them at the same time but you never know.
 
I didn't do it myself. My back decided it was tired of me climbing in and around my truck...I'm having surgery today.

Anyway, I drove down to the parts store and had the guy pull out a couple of altenators ans compared them to mine. We found one that once placed pulley up on the table stood "a bit taller" than mine. He set it up for me and we thought it was good.
 
I'm at work, so suggestions are going to be in pieces. The other thing I was going to suggest, is to run the engine with it squealing for a couple of minutes.

Then, stop the engine and carefully feel or feel close to both the alternator pulley, the drive pulley, and any other pulley touched by that belt.

The pulley that the belt is slipping in will be hot or at least a lot warmer than the others.
The belt its self will transfer some of the heat among all the pulleys, but the slipping one will be hotter.

Its rare, but sometimes its not the pulley you think it is that is causing the slippage.

Pulleys can become polished and will contribute to the slippage, but are almost never the actual cause.
If you look at any belt pulley that has seen use, it will be very polished.

You can scuff up the sides with coarse sandpaper, and it will sometimes help for a while, but the scuffs will polish out after a while.

A real longshot, is if the PO had modified the geometry of the belt drive.
There is a relationship between the amount of wrap that the belts goes around a pulley and the amount of horsepower it will transfer without slipping.

Sometimes someone will add an airpump, remove the air conditioner compressor, or do other things that cause a pulley to not have as much wrap as before and have problems.

I dreamed up a scale many years ago to determine belt and pulley problems.
I think it went like this:

Run the engine long enough to get up to temp.
Touch the pulley with an index finger:

If pulley is lightly warm, belt is in good shape and proper tension.

If pulley is too hot to touch for long, belt needs to be retensioned.

If blister forms instantly, belt should be loosened, checked for glaze, or heat damage and retensioned.

If finger sizzles and sticks to pulley, belt is probably damaged and should be replaced.

If finger flys off, turn off engine and repeat with next finger.
 
I'll try your theory but with someone elses finger. Now that you mention it the PO did eliminate the smog crap. It's still there but the belt doesn't wrap around its pulley. I'm going to do as much as I can before going to the hospital...after surgery I'm sure that truck will be the last thing on my mind. Thanks for all of your help
 
Hope the surgery is not on your finger..........
 
lol. Partial discectomy on my lower back.

I looked at the belt and it does seem to sit lower in the alt pulley then it does the others. Maybe tomorrow I'll call napa and see if they can make any sense of what will be coming out of my mouth while laid up on meds.

Also, I'll look into going to serp system but I have AC and "need" it in S. Mississippi. I'm not sure how difficult it is to switch over and keep it.
 
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