Alternator Issue

[joey0027]

Hello

I am hoping someone may be able to help with what appears to be an electrical whine coming from a Bosch alternator fitted to our old Ford Escort.

The whine can be heard faintly even when little load is put upon it & increases with engine speed. When running, the is a background crackle through the radio & what is most noticeable is when the door is opened with the lights on, the lights on alarm pitch changes with engine speed. I have checked the voltage at the battery both when running & off & the voltages are fine.

I was initially going to replace the brushes/regulator unit but as the voltage seems ok & there is plenty of meat left on the brushes, I'm not so sure. There is a suppressor/capacitor fitted to the alternator so am wondering whether this could be at fault?

Any advice would be much appreciated.

Many thanks.

[Locknut]

Is the whine interference on the radio or is it a noise you can hear directly from the alternator?

It is possible to get suppressors for fitting to components that are causing electrical interference but I would be careful about using them on modern systems.

If any wires have been moved lately check that the live from the alternator is not running close and parallel to and wires or aerial going to the radio. Also check that you have good earth connections at the alternator, radio and aerial.