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Disturbingly loud radio feedback-type noise

On really wet, rainy days, at speeds of 40+, there’s a loud radio feedback-type noise coming from somewhere in the car. At first I thought it was the radio - but when I turned it off, I still heard it. When I slow down, the noise slowly disappears. I don’t feel any difference in the handling while this is going on, but it’s very nerve-racking.

Your post caught my attention. Could the noise be described as a screeching or high pitched squeal? Moisture + Squeal is often the accessory belt(s) that are slipping. When the belts get older and are less pliable or the tensioning mechanism that keeps them tight is no longer working correctly, the belts can slip, especially in the presence of moisture when driving in the rain. If your belt(s) haven’t been changed in a while, this is what I would check first.

I was wondering about the belt as well, but I couldn’t figure out how that would be speed rather than rpm related. I.e. - at 40+mph.

OP - sit at idle and rev the motor up and down to see whether or not you can get it to make this noise.

If you can’t all I can suggest is to drive it immediately to a shop to have an experienced mechanic drive it. I can’t imagine what you mean by “feedback-type noise” - do you mean static or high pitched squeal? Either way you might have something like a wheel bearing that is about to seize up - in which case disaster will follow immediately and without warning. Someone with experience needs to drive this car and listen.

Yeah, I know what you’re saying and that’s one of the things that piqued my curiosity.

Here’s how I rationalized it; the faster you go, the more load is on the engine. Also, the faster they are moving, the greater chance of mist being produced from the wet roads and getting up in the engine compartment. If the belt is just starting to get worn out, it might not squeal even on takeoff if it’s dry but if it gets wet, then it might start slipping under load. Worth checking, it’s cheap and easy.

Well that does make more sense with the rainy wet weather. We’ll probably never know…

Thanks for the input guys. I can’t seem to replicate the noise. It’s only happened 3 or 4 times, in the last 2 years, in epic rain storms. It’s not a squeak or a squeal heard with belt issues…it’s more like an electronic feedback noise you’d hear from a microphone or musician’s amp. It’s SO loud that it’s a wonder my ears aren’t bleeding afterward! There’s only 54,000 miles on the car and I bought it new 5 years ago…the maintenance is up to date…I just can’t think of anything it would be. I’m considering an exorcism - clearly it’s haunted.

With that description it seems clear that you do have an electrical interference type of a problem. I know that you said you turned the radio off, but was the sound still coming through the speakers?

Cars are full of components that can cause electrical interference with the sound system. Someone else would have to give you the details but there are little devices (capacitors) that are attached to these things and grounded to the car to suppress the sources of interference. E.g. ignition coils have these since they create large electrical charges that can produce static & feedback problems. Alternators often have them too. I’m guessing that you have a problem somewhere with one of these capacitors. It is either loose or cracked or otherwise out of whack. When it gets wet it ceases to function entirely. Then the electromagnetic interference being produced by that part is finding its way into your speaker system.

This, of course, borders on a simple WAG. I’d be tempted to take it to someone who knows car stereos. Describe the problem and see what they think. They can locate and check out the capacitors.

My thoughts are similar to cigroller’s.

The first step for the OP is to determine if the noise is coming from the audio speakers.
If it is, then–like cigroller–I believe that interference between electrical components (alternator diodes come to mind) and the audio system are creating this problem.

I have even seen a situation where a loose connection in the audio system’s amplifier led to “feedback” through the speakers–even when the audio system was turned off.

Find out exactly where the noise is coming from and you will have a better likelihood of solving the problem.

Thanks guys!!! I’m going to look into it!