alternator

alternator?

well, my volt gauge was flickering btw 12 -14 on a recent trip.

Today, it was mostly on 12 and only occasionally made it up to 14v.

Took it to Autozone and the battery died. The Autozone guys tried to charge it with the portable charger - no luck. He then brought out a battery and tried to charge from battery-to-battery - no luck.

I think maybe the alt was weak and drained the battery beyond all hope?

Battery connections were tight and clean. Belt tension is solid.

I bought a new battery. The Autozone guys then tested the alt and all looked good except it said "diode" something was bad ...

I have an old volt/tach/Dwell meter but not sure how to test the alt ...

any help would be appreciated.

replace the alternator.

This may or may not help you but this is the way i have always tested the alternator. I would get a volt meter and with the ignition off i would test the voltage. Then i would start the motor and test the voltage again. The voltage should be about 2 or 3 volts higher when the engine is running. You also might want to get your voltage regulator checked out. I'm not really sure how to test that one.

I think the regulator is an integral part of the alternator and cannot be checked without disassembly. I would have Autozone also test the alternator on a bench stand for you. It will eliminate either if it's simply a battery at the end of it's life, a regulator in the alternator that is shot, or a missing phase or two on the alternator. SOmetimes the windings inside break and though it still charges, it charges weakly, whines, and slowly drains the battery as the overloaded coil inside the alternator looses efficiency due to heat.

you're asking the teenie-boppers at Autozone to " ... eliminate either if it's simply a battery at the end of it's life, a regulator in the alternator that is shot, or a missing phase or two on the alternator ..." ???????

to determine if " ... the windings inside break and though it still charges, it charges weakly, whines, and slowly drains the battery as the overloaded coil inside the alternator looses efficiency due to heat ..." ???????

can you explain more ??

the Hayne's manual says " ... these alternators should be considered "non-serviceable" ..."


I'm leaning with BlazerLT's thoughts to replace the whole thing ... other thoughts/ideas ????????




I think the regulator is an integral part of the alternator and cannot be checked without disassembly. I would have Autozone also test the alternator on a bench stand for you. It will eliminate either if it's simply a battery at the end of it's life, a regulator in the alternator that is shot, or a missing phase or two on the alternator. SOmetimes the windings inside break and though it still charges, it charges weakly, whines, and slowly drains the battery as the overloaded coil inside the alternator looses efficiency due to heat.

you're asking the teenie-boppers at Autozone to " ... eliminate either if it's simply a battery at the end of it's life, a regulator in the alternator that is shot, or a missing phase or two on the alternator ..." ???????

They should have a machine on a bench/tabletop or a pedestal that they can slip your Alternator into and give it a spin on a simulated load. If *I* can do it, I am reasonably assured someone else can. Ask them to test the alternator for you, and ask to watch - so you are not getting gyped.

to determine if " ... the windings inside break and though it still charges, it charges weakly, whines, and slowly drains the battery as the overloaded coil inside the alternator looses efficiency due to heat ..." ???????

can you explain more ??

An alternator, as the name states, supplies alternating current. This is achieved through not one, but three sets of windings moving through a "field coil". This rotary speed "amplifies" the relatively small draw of current taken from your battery into High voltage, high frequency AC current, much like your house current from a wall socket. But this is not what a car/truck's guts work off of easily. So each pulse made by the three moving coils, or "Phases" are passed through a regulator that turns the Alternating, high voltage current into a steady stream of 13.8 volts DC current. It's then fed down from the larger cable on the back of the alternator, directly to the battery to charge it, maintain it - and take up some of the job of powering accessories in the truck. It is possible to have a regulator fail in one or more of the three circuits (one for each phase or moving coil in the alternator) or the turns of wire that make up one of those coils fail. It therefore does what it's meant to do - make the other remaining phases or coils/regulators work harder to make up the 13.8v to maintain batery charge. This extra "stress" on the remaining, working components makes them break down so much faster. They work harder, hotter, and heat looses efficiency on these coils, so the remaining parts work harder and harder.... you get the picture now I hope. :)

the Hayne's manual says " ... these alternators should be considered "non-serviceable" ..."
I'm leaning with BlazerLT's thoughts to replace the whole thing ... other thoughts/ideas ????????

And I am not going to second guess BlazerLT and the Haynes manual either. They are both correct. Usually, the home mechanic would not have the tools and test equipment to rebuild, and then bench test the rebuit unit with any certainty. I *have* taken them apart...and promptly swapped them for a rebuilt for the core charge alone. Getting one back together correctly is a major pain in the tukus! But yank it out and have them bench test it, as I said before. That will kill two guesses in the dark with one final blow. It will nail down whether you have a tired, weak alternator or a battery at the end of it's life with one or more failed cells. Either repair/part is not that much if you get the guesswork solved with a solid test and get the right part. :) One thing you can check is using a digital multi-meter. Let the truck sit for an hour, pop the hood and take a voltage reading. A fully charged battery should hold 12.5 volts or more by itself. Then start the engine and check the voltage again. You should be reading anywhere from 13.8 to 14.5 volts initially, and then settle around 13.8 after the alternator does it's job of "topping off" the battery. Good luck, and I hope I have helped!

The one thing about those load testers is they don't test in realistic conditions when the temperatures get hot under the hood.

Heat is what makes alternators fail faster. You could have a failing alt that will test fine when being load tested at operating temperatures.

*laugh* Okay, I am not making fun of anyone here but -

...ever try to remove a failing alternator from your engine compartment after driving to Autozone? Bring your oven mits...that stays hot and *toasty* for hours on end. No joke there. Lick a finger and touch it...sizzles like a frying pan up to three hours later.

Edit: Try holding onto it long enough to get it into the store - let alone the look on the clerk's face when he grabs it! :newburn:

I had a fellow pick up a Subaru alternator that just died in the parking lot in front of the store. I had just yanked it out from under the hood and could barely touch it by holding it by the pulley. I worked the exchange since I already had the part out. He pulls another rebuilt Denso off the shelf for me, and drops it down. He then picks up the broken alternator. Now...

Most people of average intelligence turn loose of it right away and say, "Ouch". Some may even curse and swear, hop around a little....

This guy gets three steps away from the counter with it hugged in one arm. He stops. He thinks about it. I can *SEE* the reptilian hindbrain kicking the forebrain saying "Drop it, STUPID!" It repeats itself I think about three times. He drops it on the floor with a tile chipping thud. "Hey, that's hot!"

"Welcome to Arkansas." I told myself. (I am a misplaced yankee - a damn yankeed depending on who you ask. ;) )

I had to add that story when it came to mind. That was a fun moment.

For sure. I replaced mine and I had to leave the hood up for two hours so it could cool down faster.

Yeah they do tend to heat up after they're fried. I just had one that was charging but wasn't consistant and it was making a whining noise...

I'd just change it out, they're actually really easy to change.