MGB starting problem
Discussion
MGB would not start yesterday after a normal run out. stopped for petrol and then car would not turn engine over. Called recovery who claimed alternator was not charging so jumped started the car and drove the 3 mile home. I put the battery on charge and it holds 13 volts fully charged. started engine just and noted that voltmeter across battery was reading 13.5 volts which tells me the alternator is charging. I now find that the with a fully charged battery car will not turn over, I suspect the starter motor, any thoughts anyone ?
sounds like you have more than one problem.
If a fully charged battery only just starts the car the battery may be faulty (assuming the AA man jump start worked well) or possibly the starter motor, cables etc. Measure the voltage across the battery when cranking and if it drops below 10v change it.
The ignition light might be just a bulb blown but if not it points to an alternator fault. Again get the meter out and check the voltage at the alternator "Ind" terminal. It should be 0v when the engine is not running and 12v (or above) when running. 12v at rest is an alternator diode pack fault.
If a fully charged battery only just starts the car the battery may be faulty (assuming the AA man jump start worked well) or possibly the starter motor, cables etc. Measure the voltage across the battery when cranking and if it drops below 10v change it.
The ignition light might be just a bulb blown but if not it points to an alternator fault. Again get the meter out and check the voltage at the alternator "Ind" terminal. It should be 0v when the engine is not running and 12v (or above) when running. 12v at rest is an alternator diode pack fault.
Edited by Geordie MGmike on Sunday 9th August 19:20
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