Engine running makes lots of radio noise

[loco]

Hi all,
Just popped down the boat to give it a mid-winter check over. I thought we were having issues with the alternator with the voltage looking a little low on the insruments, but it was a bad connection on the instruments.

Anyhoo - I was checking the other systems, and I found the VHF had horrible background noise whilst the engine was running. Is it going to be the alternator causing this? If so, what are my options for fixing it?

Thanks in advance!

 

[Bondo]

Re: Engine running makes lots of radio noise

Ayuh,... What motor/ drive, etc,..??

 

[cr2k]

Re: Engine running makes lots of radio noise

Make sure your dash/gauges, radios, etc. have a good ground connection all the way back to the battery and/or block.

Alternator pivot bolt should be tight also.

Loose spark plugs?
Bad plug wires?

Marine electrical troubleshooting begins with cleaning and tightening ALL connections.

 

[kmarine]

Re: Engine running makes lots of radio noise

Make sure you check all ground cables. Many problembs are a result of a corroded connections. Start there, then check for loose ignition wires or other posible components. hard to tell without engine info where to look next.

 

[loco]

Re: Engine running makes lots of radio noise

ok many thanks - I'll start with that...

It's an AQ205A..

 

[HPTGreyGhost]

Re: Engine running makes lots of radio noise

As kmarine said, its probably a grounding issue. In the car audio world, we always had to watch how close we put our grounds together when using multiple grounds. In a marine environment I believe everything should go to one ground. In the a car we could normally mask the problem by dropping a part in called a "ground loop isolator" which would stop the 'whining noise', but in a marine environment you're probably better off fixing than riggin. Does the noise get louder when revving or is it constant?

 

[GLENN M]

Re: Engine running makes lots of radio noise

yeah when alts pop a diode they put out about 2/3power and ignition noise in speakers is common symton.if alt checks out ok,one of your rca patch cords could be damaged.if have a tear in insulation they act like an antenna.you can get a noise reducer for the head unit power wire from radio shack,if it isnt alt its your patch cord bettwen amp and head unit

 

[ENSIGN]

Re: Engine running makes lots of radio noise

Remove the alternator belt and see if it goes away

 

[loco]

Re: Engine running makes lots of radio noise

Hi all,
OK, we've tried a few things to try to isolate the issue. First off, we tried running the radio from the shore power, using a 12V adaptor. Noise was significantly reduced, but still audible when the engine was running. Presumably the noise was picked up from the antenna - though the shore power shares the same earth as the 12V system I guess...

Next up we took a look inside the engine bay. Since a rebuild, the HT leads for one bank were actually lying on the wiring loom. Moving the leads away with a block of wood significantly reduced the noise, even when running from the boat's 12V system. Looks like this was the main culript. Doing a radio check with the coastguard, they said our signal was spot on.

The HT leads and coil look pretty darn old, though, so we'll probably replace them. Do you guys have any particular reccomendations when it comes to HT leads and coils for this engine (AQ205A)?

Thanks for all your help, as always!