Morgan 4/4 starting problem.

I am having problems starting my 1994 4/4 Zetec 1800 Silver top engine. The battery is in good condition and holds its charge.

When attempting to start the engine it just goes ‘whrrr as if a flat battery’ and the battery indication on the dashboard drops to around 5 Volts. When the ignition is turned off the battery indicates normal level.

My measurements with the ignition OFF is 13.4V, with ignition ON is 12.5V and the measurement at the input to the starter motor is 12.4V. This indicates a voltage drop of 0.1V down the length of the cable from the rear to the front. Is this voltage drop acceptable? When turning the engine over the voltage at the starter motor input drops to 6V.

The vehicle can be started by directly putting 12V onto the starter motor input. The engine then fires up first time.

I hope it is not the voltage drop/resistance along the cable causing this as it does not look an easy job to replace.

Has any member any ideas on this problem. Thanks in anticipation.

Peter Hardy