alternator squeal?
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Fleet Mechanic
Joined: Jul 2013
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From: NE Ohio
alternator squeal?
I think it's my alternator, it happens randomly though.
Always on start up until I kick it down, and almost always on the upper limits of 1st gear before shifting to 2nd.
That to me says yes it's the belt..
But shouldn't I see a drop in voltage when this happens?
It always stays constant when the squealing happens.
I can't remember if that is normal or not since it's been a long time since I have had V-belt issues.
Would like to replace it with a larger amp one eventually, if I can find a bracket for a larger case.
Always on start up until I kick it down, and almost always on the upper limits of 1st gear before shifting to 2nd.
That to me says yes it's the belt..
But shouldn't I see a drop in voltage when this happens?
It always stays constant when the squealing happens.
I can't remember if that is normal or not since it's been a long time since I have had V-belt issues.
Would like to replace it with a larger amp one eventually, if I can find a bracket for a larger case.
Tuned
Joined: May 2013
Posts: 396
Likes: 5
From: Ottawa, Canada
What alternator is on and how tight are the belts?
I have dual v belts running the water pump and alternator. With the 130amp 3g it squeals on startup so I just temporarily ran a switch into the cab controlling the small wire on the alternator. I turn it on after starting the engine and it doesn't squeal. I'll be installing a permanent switch panel in the dash for the alternator and other items.
The other option with a 3g that I've heard of is changing an internal part that delays the alternator on startup but it may also lower total amperage output.
I have dual v belts running the water pump and alternator. With the 130amp 3g it squeals on startup so I just temporarily ran a switch into the cab controlling the small wire on the alternator. I turn it on after starting the engine and it doesn't squeal. I'll be installing a permanent switch panel in the dash for the alternator and other items.
The other option with a 3g that I've heard of is changing an internal part that delays the alternator on startup but it may also lower total amperage output.
Moderator
Joined: Jan 2001
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From: Virginia
Yep, put a larger alternator on your truck will make your squealing problems permanent. That is why they went to a serpentine belt on the late model high amp alternators. I would put a new quality belt on a stock system and tighten it up, should stop a stock system from squealing.
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Fleet Mechanic
Joined: Jul 2013
Posts: 1,997
Likes: 237
From: NE Ohio
it's a stock alternator I think 60 amp.
Belt is fairly tight, 1/2" flex in the belt if that. I don't have the tool to verify it but it sure looks close.
Putting a new belt won't hurt, I just wanted to confirm if I should see a voltage drop when it squeals since it is supposedly a slipping belt.
Which to me seems like I should see a volt drop. I really can't correlate squeal with load on alternator (or voltage display) besides the start up.
I don't want to go to 3g and deal with those belt issues.
I wouldn't mind going to a large case 100 amp alternator, but my bracket is for small case and I need to find a large case one that will fit.
I posted another thread on that so no sense in rehashing that.
Belt is fairly tight, 1/2" flex in the belt if that. I don't have the tool to verify it but it sure looks close.
Putting a new belt won't hurt, I just wanted to confirm if I should see a voltage drop when it squeals since it is supposedly a slipping belt.
Which to me seems like I should see a volt drop. I really can't correlate squeal with load on alternator (or voltage display) besides the start up.
I don't want to go to 3g and deal with those belt issues.
I wouldn't mind going to a large case 100 amp alternator, but my bracket is for small case and I need to find a large case one that will fit.
I posted another thread on that so no sense in rehashing that.
Lead Driver
Joined: Nov 2013
Posts: 7,175
Likes: 1,174
How are the belts configured? Can you remove just the one belt without disabling anything else? If so, go for a short test drive with the alternator belt removed. Obviously the alternator won't be charging, but if the noise is gone, that belt was the culprit.
Try some belt dressing, too. Any parts store will have some. It helps any V belt grip better. Took care of a squealing power steering belt on my truck.
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Fleet Mechanic
Joined: Jul 2013
Posts: 1,997
Likes: 237
From: NE Ohio
The belt may not be slipping all that much. Enough to make some noise, but not enough to significantly reduce the alternator output.
How are the belts configured? Can you remove just the one belt without disabling anything else? If so, go for a short test drive with the alternator belt removed. Obviously the alternator won't be charging, but if the noise is gone, that belt was the culprit.
Try some belt dressing, too. Any parts store will have some. It helps any V belt grip better. Took care of a squealing power steering belt on my truck.
How are the belts configured? Can you remove just the one belt without disabling anything else? If so, go for a short test drive with the alternator belt removed. Obviously the alternator won't be charging, but if the noise is gone, that belt was the culprit.
Try some belt dressing, too. Any parts store will have some. It helps any V belt grip better. Took care of a squealing power steering belt on my truck.
Thought I'd ask here first before going that route, you made a good point about it making noise but not enough to reduce output.
May be exactly what I'm dealing with.
Update: Wasn't the alternator belt, it was the power steering belt. Pump and box were on their way out.
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freef2504x4
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
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Jan 23, 2011 11:58 AM
