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MG MGB Technical - Lights that flicker

I know I should know this but....

The headlights and instrument panel lights on my '74 GT flicker irritatingly, most noticeably at 2000-2500rpm, when I'm cruising home on these dark winter evenings.

The only clues I have to offer are that the fan belt is tight and the alternator looks quite shiny.

Can you please suggest where to start working?

Many thanks.
Steve

Just for grins, connect a short jumper from the alternator's case over to a good ground to the chassis. I'm thinking that either the alternator has a poor ground or the chassis ground is marginal. Have you noticed the choke/accelerator/heater cables getting hot ??

FWIW,
Ed in 'ole Virginny
Ed Meadors III

If they are flickering off all together then look for a loose connection around the main lighting switch. If the flickering is the voltage jumping between charge and no charge (is the ignition warning light flickering on at the same time?) then it is probably worn or sticky brushes in the alt. Hook up an analogue voltmeter where you can see it whilst driving along. A bad engine/transmission ground strap would cause poor cranking long before it affected charging, IMHO.
Paul Hunt

Many thanks,

I'll set to work on it during the Christmas break and will hopefully have bright lights for the New Year.

Steve
Steve

Are you sure they are dimming?I had my lights brightening it was the alternator putting out too much 15V I replaced it on my lifetime warrenty from Lindy's and the problem was fixed!
Pat
patrick bailey

Gentlemen do not motor about at night.

JL
Joseph Lucas' Ghost

We all complain about Lucas, but some electrical problems can be more serious than any that old Joe was responsible for...

Consider the Boeing Stratocruiser, a monstrous 1950s-era propliner that looked like a pregnant B-29. Right after it went into service, a stewardess switched on a fluorescent light in the rear galley. As it flickered to life (remember that old fluorescent lights flickered awhile before staying on) she was suddenly thrown violently to and fro. Seems as though the high frequency pulses generated by the flickering light caused an induction field that affected the power to the rudder trim tab servomotor, causing the rudder to thrash from side to side! Needless to say, some additional shielding was needed on those servomotor wires.

Cheers,
Paul Kile
Paul Kile

This thread was discussed between 19/12/2001 and 21/12/2001

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