Adrian, I sent the following to the MG list for a similar occurance. It may
help.
Also, a test is to bridge or cross the 2 lage terminals on the solenoid
(car OUT OF GEAR) Ign switch OFF. If the starter spins, it is not the
battery. If it doesn't spin, it still may not be the battery, however.
Good luck.
>Folks,
> All this talk of wire wiggling and terminal cleaning reminded me of a
>simple diagnostic method. Voltage drop test. You can use a volt meter in
>parallel to a circuit to see if voltage would rather go through the meter
>than through the intended circuit. In very non-tech terms... If you
>provide an alternate path to a circuit, and the current would rather go
>that way than through the circuit, then there is a problem in the circuit.
>With a meter, you can measure the "preference".
> Specifically a starter circuit has essentially 3 circuits. The switch
>circuit: put the voltmeter between the hot terminal of the battery (not
>ground) and the small terminal on the solenoid, attempt to start. Meter
>should read .5 (1/2) volt or less. The battery circuit (cable): put the
>voltmeter on the hot battery terminal and the other end where the battery
>cable connects to the solenoid, or the starter. Whilst cranking the meter
>should be .2 (2/10) volts or less. Ground circuit: connect meter on starter
>housing and to ground side of battery, whilst cranking meter should be .2
>(2/10)volts or less. If your meter readings are higher in any of these
>tests, then you suspect the connections or the cables or switches (if any)
>in the circuit path.
> It is conceivable that if more than one of the circuits is very near the
>limit that combined the effect would be the "intermittent" problem you
>describe. And with a marginal battery, the condition is exacerbated. This
>got a bit longer than intended, hope it is clear and helpful. Clean those
>terminals.
> Peter C
>Peter C.
>MGC-GT , 100-4, '31 MM8 Cammy, Innocenti S(spoken for) ((now gone)),
>'52 Champ, '60 L-R 109 SW, 3 '64-73 L-R 88's
>nosimport@mailbag.com
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