Strange Alternator issue
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New User
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Strange Alternator issue
Hopefully someone will have an answer.
'94 Ranger 2.3 manual trans
Starts right up then Alternator makes a squealing type noise. (NOT rpm dependent)
Volt gauge sits way low.
After Alternator warms - 5 to 20 minute depending on outside temps it suddenly Kicks on/noise instantly stops and charging is 14.6-14.8. Works fine as long as running or after short shut downs. If it cools the cycle starts over. Replaced Alternator with a newer, lower mileage used unit and get the same thing.
Again - noise does not change with RPM
Thought maybe a poor ground but the truck always cranks easily.
'94 Ranger 2.3 manual trans
Starts right up then Alternator makes a squealing type noise. (NOT rpm dependent)
Volt gauge sits way low.
After Alternator warms - 5 to 20 minute depending on outside temps it suddenly Kicks on/noise instantly stops and charging is 14.6-14.8. Works fine as long as running or after short shut downs. If it cools the cycle starts over. Replaced Alternator with a newer, lower mileage used unit and get the same thing.
Again - noise does not change with RPM
Thought maybe a poor ground but the truck always cranks easily.
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
Did this problem come about suddenly, after some event????
Maybe look to the belt tensioner indicator for proper belt spring tension, tensioner & idler pully & other belt driven accessories bearings, to determine if they're going bad & seizing up.
Look for coolant, power steering fluid, or oil drips on the belt, that could cause it to slip.
If all that check out ok, maybe run this puppy by your favorite autoparts store & have them do an electrical system check up, via their portable electrical system tester, to see if you have any undue electrical loads on the system.
More thoughts for consideration, let us know what you find.
Maybe look to the belt tensioner indicator for proper belt spring tension, tensioner & idler pully & other belt driven accessories bearings, to determine if they're going bad & seizing up.
Look for coolant, power steering fluid, or oil drips on the belt, that could cause it to slip.
If all that check out ok, maybe run this puppy by your favorite autoparts store & have them do an electrical system check up, via their portable electrical system tester, to see if you have any undue electrical loads on the system.
More thoughts for consideration, let us know what you find.
Posting Guru
Joined: Mar 2005
Posts: 1,533
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From: Dexter, MI
How many miles on the truck? How many miles on donor truck? Can you exchange the replacement for another one?
If you can't exchange the replacement, you probably are going to need to buy a rebuilt one. If you do, be sure you can exchange it for another one if it is defective.
Perhaps your first step is to take your replacement one to an auto parts retailer and have them test it. That should clarify whether the problem is with the alternator. I know you are convinced that is the problem, but perhaps they can steer you to the correct solution.
If you can't exchange the replacement, you probably are going to need to buy a rebuilt one. If you do, be sure you can exchange it for another one if it is defective.
Perhaps your first step is to take your replacement one to an auto parts retailer and have them test it. That should clarify whether the problem is with the alternator. I know you are convinced that is the problem, but perhaps they can steer you to the correct solution.
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At 57 years old, I've seen some very unusual causes to seemingly simple problems. I was a mechanic/tech for over thirty years. Unfortunately with 2 sons that like tinkering on cars, most of my specialty tools are lost or non-functional.
Good possibility the replacement Alternator is no better than the original, though it has a re-manufacturer label attached.
Since the old alt is more stable I will put it back on this weekend and see if Autozone or ASR can test the replacement. maybe it just needs brushes. as it slowly creeps up to charge. the original snaps to charge voltage.
Good possibility the replacement Alternator is no better than the original, though it has a re-manufacturer label attached.
Since the old alt is more stable I will put it back on this weekend and see if Autozone or ASR can test the replacement. maybe it just needs brushes. as it slowly creeps up to charge. the original snaps to charge voltage.
Laughing Gas
Joined: Aug 2003
Posts: 1,175
Likes: 9
From: So. Cal.
To restate the obvious, it looks like electrical tests are in order. Since you say it occurs with two different alternators, it sounds to me as if there is an extremely heavy load (as in "short") during the noisy period. The only thing I could think of would be something to do with the starter. Anything else would melt or burst into flames if it is a short. It wouldn't hurt to check that the drive belt is moving at engine speed.
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Ok, lets try this again.
Original Alternator started Gradually Not charging on start. Took about a minute. As weather got colder, Delay was longer. Up to 5 minutes.
No Components Acting strange, no Smell of burning.
All Accessories - Headlights/ Horn/ Blower/ Wipers/ Radio - etc. Work fine when Alternator output correct.
It is possible I have to Worn out Alternators
Also might be a Bad connector??
Perhaps a worn Exciter wire not allowing enough stable current??
Failing Circuit ground??
I don't just yell help.
I have already checked out the Belt and Tensioner before replacing the Alternator.
Battery is fresh and Starts the truck Easily.
When engaged both Alternators will output 14.8. A drop to idle will kick out either Alt and everything (lights radio etc.) must be off while raising Idle or neither will start charging. Once driving all accessories work fine and no Drop in voltage.
The accessories issue is what got me thinking a possible exciter wire issue. Current loss.
Original Alternator started Gradually Not charging on start. Took about a minute. As weather got colder, Delay was longer. Up to 5 minutes.
No Components Acting strange, no Smell of burning.
All Accessories - Headlights/ Horn/ Blower/ Wipers/ Radio - etc. Work fine when Alternator output correct.
It is possible I have to Worn out Alternators
Also might be a Bad connector??
Perhaps a worn Exciter wire not allowing enough stable current??
Failing Circuit ground??
I don't just yell help.
I have already checked out the Belt and Tensioner before replacing the Alternator.
Battery is fresh and Starts the truck Easily.
When engaged both Alternators will output 14.8. A drop to idle will kick out either Alt and everything (lights radio etc.) must be off while raising Idle or neither will start charging. Once driving all accessories work fine and no Drop in voltage.
The accessories issue is what got me thinking a possible exciter wire issue. Current loss.
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Joined: Jan 2004
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From: SW Va
OK so the serp belt & tensioner have been checked & are ok.
Now check for a B+ voltage drop at the alternator, on the Yellow/White field excitation wire. If B+ is low there, the field windings won't properly self excite as you suspect.
If thats ok, then suspect the alternators regulator.
An in vehicle electrical system check up would likely find it & any other associated electrical system problem & it'll do it with All of the vehicles electrical components in place.
OR, if you strongly suspect the alternator, most autoparts stores can & will bench test it at no cost, just as they'll do a no cost in vehicle check-up, so why not just opt for the latter & get everything checked out in one fell swoop!!!! lol
Now check for a B+ voltage drop at the alternator, on the Yellow/White field excitation wire. If B+ is low there, the field windings won't properly self excite as you suspect.
If thats ok, then suspect the alternators regulator.
An in vehicle electrical system check up would likely find it & any other associated electrical system problem & it'll do it with All of the vehicles electrical components in place.
OR, if you strongly suspect the alternator, most autoparts stores can & will bench test it at no cost, just as they'll do a no cost in vehicle check-up, so why not just opt for the latter & get everything checked out in one fell swoop!!!! lol
Cargo Master
Joined: May 2001
Posts: 3,208
Likes: 13
I know you think the belt and tensioner is fine and they maybe. But I still think you are expierencing belt slipage. It might not be the alt that is causing it. I would apply belt dressing while it is squealing to see if it temporary solves the problem if it does then you need to see which accessory or pulley is hanging up. I have seen air conditioners cause this I have seen water pumps cause this. With the belt off how hard is it to turn the alternator it should spin freely check the other accessorties / pulleys to see if some thing is binding. My bet is both alts will pass a bench test. When an engine first starts is when the alternator is under the most load and I have 1 ton ford that will squeal the belt for second or two every time it starts and that belt is extremely tight. Pulley condition can also play a role in this problem. A worn pulley just won't grip as well when the belt heats up it gets softer and grips better.
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Will test as PawPaw suggested. just needed a bit of wiring info to get me in the right place.
I also have an Aerostar and a dodge with V-10 Both get that start up screech As does the Ranger. That noise is only momentary.
The alt noise - In both, is definitely Internal and sounds like it is toward the rear of the Alt.
Ranger is bare bones - Alt., Water pump, Power steering. All pulleys turn freely with the belt off.
Thank you all for your suggestions.
I have replaced dozens of alternators over the years but they all were either weak or had failed. This is just strange in comparison.
I also have an Aerostar and a dodge with V-10 Both get that start up screech As does the Ranger. That noise is only momentary.
The alt noise - In both, is definitely Internal and sounds like it is toward the rear of the Alt.
Ranger is bare bones - Alt., Water pump, Power steering. All pulleys turn freely with the belt off.
Thank you all for your suggestions.
I have replaced dozens of alternators over the years but they all were either weak or had failed. This is just strange in comparison.
Elder User
Joined: Apr 2004
Posts: 970
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It would seem to me that the alternators are not the cause of the noise the belt is. Disconnect the heavy lead to the alternator of course you know to disconnect the Neg battery lead first. Then reconnect the battery, noise gone? If it is the alternator is overloading the belt on initial start. How about the battery and battery size, if the starter pulls it down enough the alternator will charge max to bring it back and for some reason the belt slips. Your not putting dressing on the belt by any chance are you?