[Mgs] starter relay

[Paul Hunt]

Low voltage and/or bad connections can cause this.  Usually the problem is a
flat battery, but it can also be bad connections at the battery or starter
solenoid.  Rarely it can be bad connections in the voltage supply to the
starter relay or from it to the solenoid.  It can also be a heat-damaged
solenoid, but this is more usual on V8s with the proximity of starter and
left-hand down-pipe.  Initially the voltage is good enough to operate the
relay, which operates the solenoid, which connects power to the starter motor.
This takes a massive amount of current in comparison to everything else and
always results in a reduction of battery voltage, normally to about 10v.  That
is more than enough to keep the relay and solenoid operated and the crank and
start the engine.  But if a weak battery, bad connections or some other fault
causes the voltage at either relay or solenoid to drop below its holding
point, it will release.  This removes power from the motor, voltage goes up
again, relay/solenoid operate again, motor is powered again, voltage drops
again and so on.

Check the battery voltage on the *posts* while cranking.  If either 6v battery
is much below 5v or a 12v battery much below 10v that is suspect.  If that's
OK measure the voltage between the starter solenoid battery cable post and a
good body ground, and then between the post and the engine block.  Ideally
these will only be a few tenths lower than the battery post voltages (sum of
the 6v battery voltages), if they more than a volt lower you have bad
connections which are worth investigating.  If the 2nd measurement to the
engine block is lower than the first to the body the engine/gearbox ground has
bad connections.  If these two are much the same but they are lower than the
battery post voltages then either the battery connections, battery ground
cable to body connection, battery cable to solenoid connections, or link cable
connections between 6v batteries are bad.

Remember if you have one bad connection due to age you probably have more than
one.

PaulH.

----- Original Message -----
  My 70 B will not start despite a new battery, a rebuilt starter and
solenoid.
  All I get when I turn
  the key is a clicking noise