This LRO reader emailed LRO.firstname.lastname@example.org to ask Steve Jones about getting rid of the whine from his Range Rover Classic's radio.
My 1993 Range Rover Classic LSE’s original Clarion radio has recently begun to suffer interference, in the form of a whining noise when the engine is running. The pitch of the whine changes slightly when you rev the engine or switch on the lights, heated rear windscreen, etc. I’ve removed the coil, cleaned up all the surfaces and replaced the suppressor that fits under the rearmost bolt, but nothing has made any difference.
Do you think the alternator – which I think is the original one – needs replacing? When tested, it shows a charge/output rate of 13.75v. Is this the problem? The battery on
the car is an Odyssey PC1500, which is about two years old. Any other things I should be checking?
Grant Jobson, Worthing, West Sussex
From what you say, it does sound like the alternator. The first check to make is that the warning light is of at night. If it glows dimly, that indicates a diode fault and so the alternator needs replacing. However, it’s more likely that the alternator suppressor is faulty or disconnected. You need a 3μf between the B-output terminal and earth. The suppressor should be mounted on the alternator.
If your warning light is out then the 13.7v is far too low. You should measure the battery volts direct across the terminals after a short run with no load on the alternator, having raised the rpm to 2000-3000. The acceptable fi gure is 14.4v.
This workshop advice appeared in the Jan 2015 issue of LRO. Back issues are available to download on digital devices here.