Engine noise on AM radio

diesel crazy · August 26th, 2011, 14:25

I have the stock Monsoon radio. When I got the car back in Nov. 2010 I tried the AM radio and remember it pulling in a weak station that I listen to very well. After having the BSM done and a transmition replaced I noteced that there is a noticeable hash sound only on AM. It only happens when the engine is actually running. If the ignition is on and the engine not running it sounds fine.

Any ideas of how to track it down? Would doing the BSM and Tranny change have anything to do with it? Perhaps some ground isn't solid or some wires got put into a diffetent postition?

Any suggestion would be appreciated

abctdi · August 26th, 2011, 15:19

Old spark plug wires?

Free bump.

thundershorts · August 26th, 2011, 16:15

its alternator hash. you can put a couple capacitors on the b+ and it will eliminate the hash. most european cars already have them

diesel crazy · August 26th, 2011, 20:45

I am not sure if it the alternator because the noise doesn't change with engine speed.

diesel crazy · August 27th, 2011, 08:55

I disconnected the alternator and still have the noise. What other sources of noise would there be? Fuel pump? ECU?

thundershorts · August 27th, 2011, 12:34

you could see if its the fuel pump by pulling fuse. it may be a ground of a shielded circuit. did you try blower fan at different speeds? any motor with brushes is suspect.