[Mgs] 74 MGB starter issue

[Richard Ewald]

One long shot and two real posibilities
Long shot first, you checked the battery to chassis ground, what about the
engine to chassis ground strap?  Choke cables will provide enough ground to
run the engine, but not the starter.  Check the ground cable.  If that is
OK, the other two possibilities are:
You either have a solenoid issue or a starter issue.
The solenoid acts like a giant switch to switch the high amps from the
battery to the starter.
Here is how you test it.
Take a volt meter set it to a scale that will read 12V.  Place the red lead
on Positive battery cable from the battery.  Place the black lead on the
input to the starter from the solenoid.  Have someone turn the key to start
and hold it there.  Read the meter.
If the meter reads exactly 0V the starter it probably toast (more on this
in a minute)
If the meter reads 0.1V to about 0.3V The solenoid is working and the issue
is the starter.
If the meter reads from about 0.7V to battery voltage, the solenoid is
toast.*

Next put the red lead on the the input from the solenoid to the starter and
the black lead on a good engine ground.
Again have someone turn and hold the key in the start position.   Read the
meter
If the meter reads:
0V indicates either no voltage is reaching the starter or the starter is
open circuit.
above about 0.7V a starter issue.*

*Industry specs for these components is no more than .2V drop, but these
are old cars and frankly can put up with more of a voltage drop than a
modern car.  A 0.5V drop in a solenoid or a starter won't keep a B from
starting,so I have adjusted for this in my recommendations.
Good luck


> -----Original Message-----
> From: mgs-bounces at autox.team.net [mailto:mgs-bounces at autox.team.net] On
> Behalf
> Of William Killeffer
> Sent: Tuesday, March 19, 2013 7:53 PM
> To: Mgs at autox.team.net
> Subject: [Mgs] 74 MGB starter issue
>
> I put the gauge on right before the wire actually connects to the starter,
> and
> he turned the key. As always, we could hear the solenoid clicking, but no
> response from the starter.
>
> Assuming I had the gauge attached properly, the needle barely deflected
> when
> he turned the key. He said that in the case of a stuck starter that is
> attempting to turnover, the needle will make a large deflection because the
> starter is pulling alot of current. In this case, barely any current was
> pulled.
>
> Dad said this could be a sign of bad brushes or some other contact issue,
> especially since the solenoid clicks. The starter is no more than four
> years
> old and was purchased at Autozone. In theory, it should still be under
> warranty, but I cannot find the receipt from where I purchased it. Dad said
> that if I can drop it, the Autozone folks will test it. We know how much
> fun
> dropping the starter is, but if it makes a difference...
>
> Anyhow, I just wanted to get some additional input from the group about
> other
> issues that might be causing the trouble I am having. Any other ideas and
> suggestions would be appreciated.
>
> Thank you,
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