alternator whine

i need some clarification here. alternator whine comes from speakers right? im asking because my actual alternator whines(changes pitch with acceleration too). can this be caused by the same things as your typical alternator (speaker) whine or is it just a part of the alternator needing replacement?

Noise is either amplified, or induced. The noise you discribe above can be caused by either a faulty alternator, or from either situations of amplfied / induced noise.

Having a AVR test on the alternator will varify if one or more diode packs have faultered.

Having the electrical system checked first, will eliminate the *ghost* hunt for the noise.

If you require more help on finding the noise if it is amplified / induced because it is from the stereo system itself, just ask.

Regards

EVIL Teken . . .

can they do an avr test at autozone or advance auto parts etc.?

Yes . . .

I have just developed a whine in the area of the alternator in my car about 2 weeks ago.  This also increases as I pull away from my driveway.  However, this seems to stop after about 5 seconds and does not start again until the following morning, even though the car is standing in a staff car park all day.  Could this also be an alternator problem and if so what tests can I carry out to check this.  If it is not the alternator, what else could it be.

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Carpets

carpets wrote:

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I have just developed a whine in the area of the alternator in my car about 2 weeks ago.

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What make, model, year, and how many miles / kms are on the vehicle in question?

carpets wrote:

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This also increases as I pull away from my driveway.  However, this seems to stop after about 5 seconds and does not start again until the following morning, even though the car is standing in a staff car park all day.  Could this also be an alternator problem

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This can be either a alternator or a circuit fault as it was discribed above.

ie. Induced / amplified noise

carpets wrote:

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and if so what tests can I carry out to check this.  If it is not the alternator, what else could it be.

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As it was stated above a standard AVR test will determine if the the charging system is indeed at fault.

I would like to mention and stress to you the following.

Newer vehicles today employ *Avalanche Diodes* and many automotive repair facilities cannot measure the diode pack correctly for nominal operation using standard diode check methods.

If the shop has updated testing equipment such as Midtronics testing tools, or a scanner osciliscope then the square wave form can be captured for ripple(s) which then can determine if any of the eight diode packs are damaged.

Older testing equipment will pass Avalanche diodes almost all the time, due to their low voltage output.

Which then leads you down the wrong path. Remember, you can have 5 of the 8 packs damaged or fewer, and the vehicle will continue to operate as the battery acts like a filter and will absorb some of the unrectified or leaking AC voltage.

Do not let Jimmy Joe Smith who has no electrical trouble shooting do the test. You want a qualified professional to capture and display the square wave for you so as you can see for yourself, which should have almost no ripple in the wave form.

I will address how to trouble shoot the other Q later.

Regards

EVIL Teken . . .

Teken

Thanks for your advice regarding getting an AVR test done.  As asked, I have a Fiat Punto, 1999/2000 reg (W).  The vehicle has done 385000miles.  Could this determine what the fault could be?

Once again, thanks

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Carpets

I will need some additional information. Is the sound system OEM? If not, what type of equipment.

Has anything changed in the electrical system or additional accessories been added?

Please let us know.

While you are waiting, I would follow up on the basics.

If there is only a OEM sound system and the vehicle has not been modified electricaly in any manner. Given your miledge, one would have to suspect the alternator as being the culprit, or a wiring fault.

Without a the proper tools to do a diode check, you are simply guessing.

Some of the shade tree methods to varify certain area's of the alternator is to perform various load tests while the vehicle is off and while running.

The simplest test for alternator whine is simply to listen to the stereo without the car running. If you are running on battery power alone, and you hear the whine, pop, hiss, then the problem lies elswhere in either the wiring, or components.

As you mentioned prior, the whine / noise flutuates as the RPM's increase. This does indicate the alternator *may* be the cause. But does not address if the noise is caused by a failed diode pack(s), or simply from induction / amplification.

To start, ensure all power and ground points to and from the battery to the alternator are clean, tight, and properly crimped to their respective terminals.

Every vehicle has a secondary, or third grounding point attached to the engine. It may simply be wired to the valve cover, or side posts to the rails. Ensure all ground points are clean, tight, and properly crimped / terminated to their bindings.

One of the oldest shade tree ( wand ) tests to varify a diode pack failure (ONLY) when more than one pack is faulty is simply using a flourescent lamp while it is unplugged and waving over the engine while it is running.

If any RFI / EMI in the 50-60 Hz is present it will make the light flicker. You must do this in the dark, and while the vehicle is being revved up and down!!

You may also want to ensure the following components within the ignition system are sound, and in good operational order.

Distributor cap, rotor, spark plugs, ignition wires, stator, and ignitor, coil.

All of the above vehicle related ignition units will cause the very same alternator whine / noise you hear while revving, and may go away.

Why?? In the distributor cap it is made of insulator of dielectric plastics. If you remove the cap, and see within the moulding any signs of what may appear to be small lightning bolts coming through, or running along the cap. This is called tracking . . . Carbon tracking is the last sign of the dielectric plastics in its life span, and electrical energy is being absorbed, instead of being deflected. If this is see, replace the cap.

The internal rotor which the is within the distributor cap is also a root cause, upon failure the spinning metal guide becomes a antenna, which radiates any stray RFI / EMF. It should also be noted that the actual retaining set screw is none ferrous coated (insulated).

Meaning it is not suppose to become magnatized. If it has been reused over and over, the coating will wear away and thus, the insulator on the set screw will be ineffective. Then at that point the actual screw will act as a antenna, and use the rotor as a amplifier to radiate the RFI / EMI.

The spark plugs upon terminal wear will do the exact same thing as discribed above. Once upon a time all spark plugs were insulated with porcelin. That is not the case, and many plastics, or semi-ceramics which
are suppose to be insulators, do not fair well during prolonged service.

So replace as required. The last items, you will need to use a manual to varify their proper resistor / voltage tolerances.

The spark plugs should be one of the first things you should always inspect. Upon removing the wires, take each one and do a pull test. Any signs of the boots tearing, stretching, or obvious cuts, or insulator wear, replace them.

All domestic igintion wires will measure around 50 K ohms of resistence or less.

Most imports require a resistence of less then 12k ohms. Read the makers tolerances to ensure you fall within the specified resistence.

Idealy, you would want the least amount of resistance so as the maximum of current / voltage spark reaches your spark plugs, so as the air / fuel combustion process is as complete as possible.

But the makers do not simply shoot for that, in terms of current transfer. They must ensure that the amount of transferred current does not start the process of induction, whereas why the need for resistive plugs, and wires.

Take a DMM and measure the spark plug wires, ensure all terminals are clean and free of any debris and contaminates. Always apply some dielectric grease compond to ensure current transfer, and to inhibit moisture build-up.

If the stereo system is after market, please let me know, and we can address each item, one by one.

Regards

EVIL Teken . . .

Teken

With reference to the comment made about whether anything has changed in the electrical system or accessories added, this is a 'No'.  With respect to changing spark plugs (or at least chcking them), this was done in a service back in August when we had our annual service.  These we know are now OK.  With respect to the other points highlighted regarding the various checks, I will check these out.

Thanks for the advice

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Carpets

Carpets, you said the noise is coming from the area of the alternator. Last time I checked, people don't put speakers in the engine compartment.

Also, alternator-induced interference (which is REPRODUCED through speakers) doesn't go away, it's constant with the engine RPM.

This is a car audio board of course, but could it be the fan belt? A mechanical noise?

Also, was that a trick question? :)

///Leif

Leif]d wrote:

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esn't go away, it's constant with the engine RPM.

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That statement would be inaccurate. A alternator who's diode packs are degrading gradualy will produce intermittent spurious noise at varied intervals.

The constant whine / noise people refer to is the end result of two or more complete diode packs which have failed.

Again, this assumes the noise is being caused by the alternator, and not infact from other sources of induced or amplified generating units / wire(s).

Regards

EVIL Teken . . .