Bluetooth in a diesel w123 feedback?
 

I have been told lately that I have a ton of feedback when using my bluetooth head unit in my 300D lately. Interestingly I used to have really good call quality and I havent changed anything (same phone, same head unit). Normally I would suspect EM from the ignition system as causing problems, but obviously there is no igniton system on a diesel, and not even high frequency noise from electronic injectors. Does anyone else have this problem? I might just swap out the head unit but I hate to spend the money without knowing that it will fix anything.

Possibilities, blower motor or aux water pump?

Also, is your rear fader still connected in the console? I've read somewhere that it can be a source of noise.

Could be a bad alternator diode.

whine that varies w/engine speed is usually alternator related. Is the issue present with the engine stopped but the ignition key in the 'on' position?

AC current caused by bad diode is common in a Dodge Ram. Search "AC noise test" on youtube. It's easy to test if you have a decent volt meter.

I haven't had any complaints aside from the engine noise in the 240D. I don't often talk on the phone though. Music streaming is perfect. I have a Pioneer in the 240D and a Kenwood in the 300TE.

Are you talking about feedback complaint from the person you're talking to while on the phone through your Bluetooth radio? Try using your rear speakers only.

Thanks for the suggestions people. I am having the complaint of "electronic noise" and "feedback" when I talk to my folks. I initially thought it was an echoing noise, but I guess I was mistaken there. Blow/Aux pump are great suggestions. The aux pump is brand new, but the blower motor is original - it might need new brushes, and it definitely needs the bearings greased or replaced. Alternator diode is another good possibility, I'll do some research on that. It also just occurred to me that I don't have the radio-interference springs (not sure the proper name) installed in the front wheel hubs, they were missing when I bought the car.

I'lll try making a call with the engine off and the car in run and the climate control system off - that should tell me a lot. Thanks for all your suggestions.