[gmc1941]

Found a tip on radio noise.
There is a simple test you can do to determine if the noise is coming in through the hot wire or the antenna. Tune the radio to an area in the AM band (this will not work on FM) where there is no station. With the engine running and the volume turned up, tune around until you find the noisest spot. Now reach down and unplug the antenna from the radio. If the noise disappears or is greatly reduce, you have found the source of your radio noise. The common cause of engine noise is poor ground at the antenna end of the cable. Copied from "Wired for Sucess" by Randy Rundle with out his permission.