Engine Interferance w/ Radio

if you have a distortion analyizer or access to one you can see what is happening at line level.  You can always put a filter inline to remove any unwanted harmonics out of the system, but I have never seen a factory radio/replacement radio without amps give the "alternator wine".  The other question I would ask, is it really engine noise, or could it be you have a bad speaker somewhere that just responds with distortion when operating at certain levels???  Maybe a bit more of  a description of what you are hearing would help. 

Let me know

Craig

Radio noise is a troublesome thing to get rid of sometimes.

Only happens when you play the radio----It is in you antenna.  check the ground on the antenna mount first!!!!!   Then after you are sure that it is clean and has a killer connection, trace the antenna back to your deck making sure that it does not run next to any power wires and that the shield is not cut or chafed.

If it persists, I would replace the antenna anyway because it might be inside the antenna itself.

Joe said: "Its only when i play the radio, the cd player is not effected, and when the engine is off i dont get any interferance"

Joe, if it were me, I would do what Jeff said last.  No offence Jeff.

If you find that the antenna is ok and you opt not to replace it, then my next step would be to run a different ground from the deck, as short as plssible and now where near any other power wires, to the firewall.