Alternator whine through radio - how the eck do you fix it!!

[dave_s13]

So, car is a 2006 Toyota Celica VVTLi - 65k miles.

Problem is the sodding stereo whines like a mutha when tuned into a radio station. Symptoms thusly:-

- Pitch is related directly to engine speed
- Varies in volume seemingly based on atmospheric conditions - can vary from midly annoying to needing to be turned off.
- Completely disappears with CD on
- Worse on radio 4 - how am I supposed to keep up with womans hour!!

So far all I've tried it attaching a bit of wire to the earth side of the FM aerial in the back of the unit and attaching that to the chassis - no joy.

Can someone post up some practical advice on what to do, where and how to do it please.

Most grateful.

Other than that it's a fabulous car, engine it a joy, I just don't want to hear it over the top of Winifred Robinson.

[Krikkit]

You need an FM filter, but I'm struggling to find one for sale over here. Interesting that a google brings up a suggestion to change the belt if the old one is worn.

[sc0tt]

Noise Supressor

http://www.ebay.co.uk/itm/10A-NOISE-SUPPRESSOR-FIL...

[Mr2Mike]

Is this the original head unit? Have any additional amplifiers been added?

[smartphone hater]

There are a few reasons for this including knackered alternator or bad wire routing in the car. If you've just got a normal car stereo fitted with no extra audio equipment like an amp I'd try an in line filter first.

[The Wookie]

Don't rule out the head unit itself.

Had this from a retro style head unit purchased from the states for our 68 Mustang, all wiring checked, two separate head units tried, eventually decided to bin it and put a basic looking Clarion in and it disappeared.

[Devil2575]

You shouldn't get this on a modern car. It used to be quite common 20 or 30 years ago but cars designed from the outset with hifi systems installed as standard shouldn't really give this problem.

Have you installed some after market stereo bits yourself? An amplifier perhaps?

If not I'd get your wiring checked by an auto electrician.

On a related note I was driving behind an old 1950s Rover a few months back and every time I got close to the car my radio picked up the same kind of noise. As soon as I let him open a gap it disappeared.

[dave_s13]

Thanks for the responses chaps.

Apart from a Parrot kit that I fitted the car it's completely standard. It whined before the Parrot btw.

Re the filters linked to on ebay...I can't see ebay at work, can someone post up a picture....where/how exactly are they fitted??

[TonyRPH]

Many years back, I worked in a car radio fitment centre.

This kind of noise was common back then, and the fix was always a missing / faulty earth connection to the back of the radio itself.

99% of issues were cured by running an earth wire from the back of the radio to the bodywork (the closer to the battery earth the better).

In cases where a separate amplifier was installed, again, it was always an earthing issue.

My 2000 Honda Accord Coupe does the same thing - and as yet I've been too lazy to remove the (aftermarket) head unit and look, but I'm 100% sure it's a loose / missing earth.

I can even remember in some really bad cases, we would disconnect the earth wire in one side of the aerial, to break the earth loop that this was creating.

Some cars seemed to have really poor conductivity between various body panels for some reason, presumably due to sealant between panels etc.

[GuinnessMK]

When I built my kit car we had to use suppressed ignition leads. I'd guess all spark plug leads these days are already suppressed? Unless there is a loose connection somewhere from coil pack to spark plug?

[CraigyMc]

Question:
Does a portable radio, powered from its own source (so not on the car's power) have the same interference or not?

• If yes, then the alternator (or something else, but likely the alternator) is generating a lot of electrical noise and no amount of suppression will cure it. Replacing the dodgy part will.

• If no, then look into the other things.

How hard is it to get a portable radio?

C

[CraigyMc]

GuinnessMK said:

When I built my kit car we had to use suppressed ignition leads. I'd guess all spark plug leads these days are already suppressed? Unless there is a loose connection somewhere from coil pack to spark plug?

Why guess?

Testing's better.

C

[jones325i]

So what you've got is essentially the engine sound augmentation that BMW are using now.

[SMGB]

CraigyMc said:

Why guess?

Testing's better.

C

All ign leads are resistive now but thats not the problem here, Spark interference is very distinctice, rarely heard now but last month I was next to a lovely MGJ2 at some traffic lights and I could use the Fiats radio as tachometer for his engine.at idle it was blat blat blat. So that car had a period correct ignition set up. Thia is alternator noise conducted along the cars wiring, as noted an inline filter and attention to earthing will cure it.

[lestershaw]

if you have an i phone connection on your head unit, then just stream the radio stations from an app such as "tune in radio" which is what i do?

[dave_s13]

TonyRPH said:

.99% of issues were cured by running an earth wire from the back of the radio to the bodywork (the closer to the battery earth the better).

I can even remember in some really bad cases, we would disconnect the earth wire in one side of the aerial, to break the earth loop that this was creating.

Currently the aerial plug that terminates into the back of the radio has wire attached to the ground and this is then attached to a solid looking bit of the cars structure....no difference.

Plug looks a bit like this
My wire is attached to tubular casing bit, not the central prong.

CraigyMc said:

Question:
Does a portable radio, powered from its own source (so not on the car's power) have the same interference or not?

• If yes, then the alternator (or something else, but likely the alternator) is generating a lot of electrical noise and no amount of suppression will cure it. Replacing the dodgy part will.

• If no, then look into the other things.

How hard is it to get a portable radio?

C

I can try this, i've got a portable radio on my desk - I'll try it at lunch.

jones325i said:

So what you've got is essentially the engine sound augmentation that BMW are using now.

Yes, but it doesn't really sound like an M5!

lestershaw said:

if you have an i phone connection on your head unit, then just stream the radio stations from an app such as "tune in radio" which is what i do?

It's a workaround, I'll give you that....a rubbish one though

[jones325i]

dave_s13 said:

jones325i said:

So what you've got is essentially the engine sound augmentation that BMW are using now.

Yes, but it doesn't really sound like an M5!

When I was a little lad and my older bro was about 18, the radio in his MK2 Fiesta used to make a kind of buzzing/farting noise that matched the engine revs, but only when tuned to a certain frequency. I though it was great at the time .

[TonyRPH]

If you turn the volume right down, turn the headlamps on full beam (to create more load on the alternator) - do you hear even the faintest whine?

I suspect you will hear it very faintly, if you put your ear to a speaker, even when CD mode is selected.

If it has only recently started doing this, and you've made no other changes to the vehicle, it could be impending alternator failure. Sometimes one of the diodes in the alternator going 'leaky' can cause this too.

The fact that a) it's a whine and b) it's directly associated with engine speed tells me it's not interference from the spark plugs.

Interference from the spark plugs / HT system is usually a tick, tick, tick type sound (which obviously also varies with engine speed), and will be *very* audible on AM radio.

Edited by TonyRPH on Tuesday 14th May 13:53

[big_boz]

I would be checking the earth on the head unit first.

[dave_s13]

big_boz said:

I would be checking the earth on the head unit first.

No such thing as a daft question is there?

How do you do that then?