blocking alternator wire noise?

Swapped engines in my car, and while doing so put in a new alternator. After chasing down some noise in my car with a Monster cable noise sniffer, I found the wire from my alt is the culprit. Car running, alt cable attached, noise is horrible loud. Car running, alt wire disconnected, noise it gone. Pic of the wiring. Power wire runs from connector to visible circuit breaker, drops straight down & runs along firewall to drivers side & enters firewall. Alt wire you can see leaving the fuse panel, crosses the ground wire & then hugs the tranny & engine to the alternator, roughly 12" away from power wire at its closest point (except at battery of course). The blue wire running from batt terminal to the left side of battery is the main power for the car & enters the fuse panel right next to the alt wire. The noise is most definitely coming from the alternator , and I think it is infecting everything else. How can I filter the noise from the alternator? It is driving me crazy and I have been driving the last couple months with the radio off just because of it. Need ideas.......Unless it raises the hair on the back of your neck, its only noise!

On a scale of 1 to 10 with ten being the worst engine noise you have ever heard, what would you rate this noise?   If it is in the 7 to 10 range, do you have a pioneer deck?

It would be probably be a 7. At low/mid volume the whine is almost as loud as the vocals, as I crank the volume it gets less noticable but is still there. It doesnt change with volume, its just so loud that the volume has to be quite high to completely cover it up. I have a JVC KD-AVX33. The noise is coming from the Alt. Deck is powered & grounded at the battery, amp ground is almost perfect, and with a noise sniffer the power wire goes through the roof, but if I unhook the alternator the noise sniffer reads almost nothing on the power wire. I think I need something to clean the power coming from the alt, because it IS the source of the noise.Unless it raises the hair on the back of your neck, its only noise!

Sounds a lot to me like your RCA cables have lost their groun referrence, but since you insist that the alternator IS the source of the problem, we probably should not waste any time checking this.

Already checked RCA cables, so rechecking would be a waste of time.Unless it raises the hair on the back of your neck, its only noise!

I have tried pretty much everything there is to trace down this noise. I found THIS link for a capacitor by MSD to filter their ignition systems incase of added noise. I assume this is a polarized capacitor, opposed to the traditional non-polarized caps. Anyone think this could do the trick? I cant find any specs on it :(Unless it raises the hair on the back of your neck, its only noise!

Just for fun, how about you toss a meter on there while the car is running. At the battery, you should see 14.4V DC with the car running. There should be almost no AC voltage when you flip the meter over to AC. Tell us what you measure. Oh, and how is the ground for the engine block? The accessories bracket is grounded too, right? Block grounded back to where the battery ground is?Wherever I go, that is where I end up......

AC reading between the battery ground terminal & the Alternator wire. Battery has 0/1 ga ground wire to strut tower (oem location). Engine ground 1 is 4ga from tranny housing to lower chassis (oem locations), and 4ga from same lower chassis location to battery ground terminal. Engine ground 2 is 4ga wire from aluminum head to drivers side upper chassis, oem locations. I tested ground points all over the car & everywhere reads equal to or lower than .2 ohms to the battery ground terminal.Unless it raises the hair on the back of your neck, its only noise!

I can't make out the markings on your meter. If it is on an AC Millivolt scale, 31.3 millivolts should not be a problem. However if it is not a millivolt scale, 31.3 volts of AC would cause more problems than a lot of alternator noise. Try putting the black meter lead in the common jack in the middle of the meter. I know technically it is connected to that lead via the shunt of the ammeter of the meter. But just to make sure there is no problem with the ammeter shunt, take the reading again with the lead in the common jack.

No that is volts, not milli-volts. Switched ground wire to COM port & the reading didn't change. I put a 1farad cap under the hood today (temporarily for testing) to see if a normal cap might take the noise out. I tried multiple wiring configurations & nothing worked at all. I also put the alt wire directly to the battery (I read it on an aviation thread) and that also didnt remove the noise. Also ground the alt directly to the battery & that did nothing either. Alternator is under 1yr old. Nobody has ever had this problem before?Unless it raises the hair on the back of your neck, its only noise!