MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Bench Test Alternator?

I've acquired a spare Lucas alternator but don't know if it's in good condition.

Is it possible to test on a work bench using only an ohmmeter?
Is it worth doing given the widespread availability of aftermarket replacements at parts stores?

Thanks,
Dan
Dan Hiltz

You probably need to spin it and use a voltmeter as a minimum to see if it's working at all, but also be able to supply sufficient load and rotational speed to check it's maintaining at least 12.5v at full load.

It will need a battery between it's output terminal and body, and the equivalent of an ignition warning light between the IND terminal and the output terminal to give it the initial excitation. Without that it may have to be revved to the equivalent of 3000rpm before it starts charging instead of the usual 900-1000rpm. Once started it should continue to charge down to about 600rpm.

All-in-all probably easier to fit it to an engine! When used spares came my way for both cars I did trial fit and test them, putting the originals back afterwards.

A bird in the hand is worth two in the ... parts store.
paulh4

Dan -- Most consumer auto stores in the US (Auto Zone, Discount Auto, etc.) Will test alternators for free. They already have a test stand. The fact that its Lucus won't matter. You're under no obligation to buy anything.
Bruns

This thread was discussed between 02/05/2025 and 03/05/2025

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.