Alternator whistle sound

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340Duster247

340Duster247

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hey guys installed a new tuff stuff 130amp 3 wire.
Took it out for first test drive and at around 2000rpm it sounds like I have a boosted engine lol. No idea what it could be. It's pretty loud... 100% coming from the alternator
Any ideas?
 
Some alternators whine, as mentioned above, louder under heavy load. "It might be' something dragging internally. I'd examine it before you run it "toofar."
 
tighten belt? Maybe 2K is when its starting to put a drag on it.
 
It's pretty damn tight It reminds me of the sound we would get back in the day when you would have an amp and a stereo and you could hear the rpm noise coming out of the speakers from the amplifier Sounds almost like a supercharger
 
disconnect its wiring and run it. See if it wines? Hey, it sounds like a supercharger..is that a bad thing? ;-)
 
Lol I know. Sounded cool that's for sure but .....I'll dig deeper tommorow.
 
The definitive test to determine if this is electrical is to unhook the regulator/ exciter wire and see if it quits

If it's as loud as you describe and the battery is "up" it might be loose laminations in the stator, IE a candidate for a defective replacement You might contact Powermaster, "whoever"
 
Hey guys started car and whistle has gotten quieter. Sound goes away when electrical disconnected.
 
So I contacted tuffstuff about the problem and they said I must have a solid state regulator...???
This is the regulator I have.

IMG_2243.JPG
 
14.6-14.9volts the sounds is around 2500/3000 rpm
Sometimes I get the odd 15.1 volts.

I just picked up that mopar voltage regulator. I currently have a cheap silver one. I'll install it tonight and see if it changes anything
 
There might be voltage drop in the blue wire that goes to regulator, also insure good ground at regulator case. 14.9V is a volt high, there must be drop between blue wire and battery. Long term in hot weather, it will boil the battery. The drop is often in bulkhead connectors. The drop can be measured from blue wire to battery terminal. As a test, jumper + battery terminal to blue wire, see is sound goes away. If it does, fix connection problems.
 
340Duster247 said:
14.6-14.9volts the sounds is around 2500/3000 rpm
Sometimes I get the odd 15.1 volts.

I just picked up that mopar voltage regulator. I currently have a cheap silver one. I'll install it tonight and see if it changes anything
Click to expand...

As Dave said above you likely have a voltage drop problem

There are several ways to check for it, here's how I do it:

Turn key to "run" engine stopped. Stab one probe of your voltmeter into the top of the POS battery post. Hook the other probe as close as you can to the regulator blue. This will be either at ballast resistor or the blue alternator field wire

You should measure a very low voltage, the lower the better. More than .3V (3/10 of one volt) you need to look for the problem.

Example: If your regulator is properly regulating 13.8---14.2, and you have 1/2 volt of drop in the above test, your battery will charge at 14.3---14.8. In other words the voltage drop causes charging voltage to RISE by the amount of the drop

Also, the ground circuit can be a problem.........

Run engine, fast idle, test with all loads off, and again, with lights, heater, etc running

Stab one probe into the top of the battery NEG post. Stab the other into the mounting flange of the VR case. You again should read VERY little voltage, the less the better, ZERO is perfect
 
Hey guys sorry I've been MIA been busy for me. Anyways got a new voltage regulator and my voltage stays right where it needs to be. 13.8-14.5.
The odd time when car is hot and fans on at idle it gets down to 12.8 .....

I'm still getting the whistle at around 3000 rpm. Quite loud. And when I rev and it comes back to idle you will hear a quick whistle.... also at idle the headlights and tail lights strobe. The strobe gets faster with rpm.
I've checked all my grounds and so far I haven't noticed anything bad.
 
Might be a bad diode, or two. Alternators generate three phase AC, and use 6 diodes to rectify. Loss of a diode, reduces power output, and makes the output bumpy, hence noise and strobe.
t37gL.gif

The green line in bottom trace is correct DC waveform, the battery filters, and makes it a straight line. Imagine loss of the red #2 phase, the green would then only follow the black and blue, resulting in significant dips, where red peaks. The regulator does not fix, it actually makes it worse. When the regulator sees the dip, it increases field, but that is not enough, then when blue phase is encountered, the voltage spikes high, before regulator compensates.
 
Last edited:
KitCarlson said:
Might be a bad diode, or two. Alternators generate three phase AC, and use 6 diodes to rectify. Loss of a diode, reduces power output, and makes the output bumpy, hence noise and strobe.
Click to expand...


Don't know why I did not mention that, agree completely. With the car running at fast idle, turn on the headlights, take your multimeter and switch to AC volts. That's RIGHT, "AC" and NOT "DC"

Read from alternator output stud to the engine block and post back here. It depends on "who you read" but more than 1/2 volt is darn sure high

Here

http://assets.fluke.com/appnotes/automotive/beatbook.pdf
 
In the test above, turn on more loads for the test, fans, lights ..., otherwise the battery will supply most of power demand and significantly reduce the AC component.
 
I think you guys are right and this alternator is garbage. Just took the car for a long rip on a hot day.
The volt guage was only showing 11.8 volts at idle. And get to a max of 12.8 driving. Ugghhhh supp to be a 130amp alt. My stock one did better.
 
67Dart273 said:
Don't know why I did not mention that, agree completely. With the car running at fast idle, turn on the headlights, take your multimeter and switch to AC volts. That's RIGHT, "AC" and NOT "DC"

Read from alternator output stud to the engine block and post back here. It depends on "who you read" but more than 1/2 volt is darn sure high

Here

http://assets.fluke.com/appnotes/automotive/beatbook.pdf
Click to expand...
Thank you
 
Ok guys another update. Did some tests and at alt I'm getting 13.8-14.3 volts. With dual fans on. At battery getting 12.5-13.2. (Batt in trunk)

Now about the strobing headlights. When car is idling with fans off they strobe but when fans come on they don't.......

Sorry for being all over the map. I'm not sure why earlier voltage was getting down to low 12s.
 
Different voltage at trunk vs alternator suggests 1.1 to 1.3V drop in voltage, about 5 to 10x more than desired. That indicates poor connections, terminals, or too small of cable.(s). That would also make cranking engine difficult. We do not know how the wiring was done.

67Dart273 suggested an AC measurement, what reading for that, at alternator stud?
The battery is the filter for the alternator ripple, having it electrically remote, increases voltage ripple. The less ripple when fans are on, suggests the back EMF from them is helping, so do test with them off.
 
Last edited:
KitCarlson said:
Different voltage at trunk vs alternator suggests 1.1 to 1.3V drop in voltage, about 5 to 10x more than desired. That indicates poor connections, terminals, or too small of cable.(s). That would also make cranking engine difficult. We do not know how the wiring was done.


67Dart273 suggested an AC measurement, what reading for that, at alternator stud?
The battery is the filter for the alternator ripple, having it electrically remote, increases voltage ripple. The less ripple when fans are on, suggests the back EMF from them is helping, so do test with them off.
Click to expand...

4 gauge from alt to starter then 1 guage from starter to battery. I'll double check connections.
Zero problems cranking.
I did the test as stated before and got .2-.1 @ alt stud. Hope I did the test right.
I'll do the test with them off and report back

Thank you
 
Ok did another test. Alt at 1000rpm is putting out 14.1-2 volts. Checked at battery and is the same. The gauge on my tbinjection(fitech) reads 13.6-8.

Did ac check with no fans on and got the .1 at alt stud.
 
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