use a "ground loop isolator" f.ex. from
http://www.radioshack.com/product/index.jsp?productId=2062214

On Sun, Apr 3, 2011 at 2:12 PM, Jack R. <jack007@comcast.net> wrote:
> Suggest changing the spark plugs... new resister plugs, and/or plug wires.
>
> Jack R.
> 84 Westy Wolfie
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Alistair Bell
> Sent: Friday, April 01, 2011 8:58 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: radio whine, need help
>
> A �few months ago the radio in the van has developed a whine when
> engine running. You know, increasing frequency with engine speed, and
> no whine at all when engine off. It's present on all inputs: tuner,
> cd, aux, usb.
>
> Came on all of a sudden, and only on the front speakers which are
> powered by separate amp and go through crossovers.
>
> What I have done:
>
> -redid all grounds, signal, and power leads to front speakers,
> crossovers, and amp - no change
> -swapped in another amp - no change
> - tried alternate pair of rca jacked leads from head unit to amp,
> straight run, not crossing power lines - no change
> - new antenna and lead to head unit (old one was really bad at head
> unit) - no change
> - if i grounded amp directly to battery post instead of body, noise
> was louder. BTW, the amp ground wires are a short run twisted trio.
>
> Recently the noise has become louder and worse.
>
> Today I pulled the alternator and:
>
> -pulled brush pack and cleaned connections
> -pulled the noise reducing caps on alternator and cleaned connections
> -removed the diagnostic plug (TDC sensor lead and plug) from alternator
> -pulled distributor cap and cleaned, above and below black plastic
> shield
> -cleaned up edge of rotor
> -cleaned all the grounding points (pivot bolt area etc) on alt body
>
>
> these things have improved things, the whine is much quieter.
>
> Can anyone suggest anything else?
>
> thanks
>
> alistair
>