Morris Minor Owners Club

Hi,
Recently I've found that the ignition light in the traveller seems to be coming on whenever at higher revs so when accelerating or cruising over about 35mph and doesnt go off again until I slow right down. The brushes in the dynamo were changed a couple of months ago and worked fine but it was only very recently converted to negative earth, what's the likely problem?
Thanks, Andy

Loose fan belt?

Knackered/wrong fan belt?
The belt should ride in the V of the pulley, not at the base, have a look at it's surface to work out if there is a problem.

Well I tried to tighten the fan belt and it seems to have made it worse, the light now comes on even earlier. Should I just try changing the belt completely then?

With the engine switched off (Got to say that or some daft bugger will try it with the engine running), grab hold of the fan blades and try turning them.

The fan turns easily and turns the dynamo with it...

Problem is more likely then to be sticking brushes. But a better diagnoses would come with use of an ammeter and a volt meter !

It should be stiff enough to try to turn the crankshaft

Changing the fan belt made no difference, looks like the new brushes didnt last long then! I'll look into it. Though would it definitely be nothing to do with converting to negative earth last week?

Well - as long as you repolarised it correctly ?