Have a look at the ignition warning light as you turn the key to start.
If it goes out or very dim then there is insufficient charge in the battery
or you have bad connection(s) in the heavy current circuit - remember to
check the battery and engine or gearbox ground straps as well as the cable
connections. You can test these by connecting a voltmeter from the hot post
(not the connector) of the battery to the hot post of the solenoid (better
still the strap between the solenoid and starter if you can get at it) and
turning the key to start. Note the reading and then do the same from the
ground post to the starter body. Ideally you should have no more that 0.2v
each time. More than 0.5v is worth cleaning connections, the voltmeter will
allow you to see which one(s) are bad by testing each connection in turn.
If the ignition warning light does not dim then you have a disconnection in
the starter solenoid circuit somewhere. A was just on the cusp of the
changeover from inertia (remote solenoid) to the pre-engaged (which also
gained a starter relay in 69).
If you don't have the relay (i.e. you have a white/red on the solenoid
instead of a white/brown) then the click you are hearing could be the
solenoid operating but the contacts are bad, check with the voltmeter on the
heavy current terminal of the starter. If there is nothing check back at
the output terminal of the solenoid. If you see 12v there then the cable
between the two is bad. If you still don't see 12v (key at start, of
course) then the solenoid is bad.
If there is 12v at the starter terminal than the starter is bad either a bad
segment - you should be able to turn the starter by putting a spanner on the
square shaft at the back, that will allow you to turn it to a different
segment - or bad brushes.
The pre-engaged starter without the relay is just the same, except you may
not be able to test the link between the solenoid and starter.
If you have the pre-engaged starter and the relay you could be hearing
either the quiet click of the relay, or the louder one of the solenoid. If
the former check for 12v coming out of the relay on the white/brown spade
and check that it is arriving at the solenoid spade. If there is nothing
coming out then the relay is bad, if it gets all the way to the solenoid
then the solenoid is bad, otherwise you have bad connections on the
white/brown.
Be prepared to see what appear to be low voltages at the solenoid operate
spade (white/red or white/brown). I am currently (Ho!) investigating a
chattering starter on the V8 and thought I had found a bad connection in the
operate circuit when I measured about 6v at the solenoid. I discovered that
the pre-engaged solenoid has a resistance of about 0.6 ohms, i.e. it tries
to draw about 20 amps. Dropping 6v through the brown, relay and brown/white
circuits with that amount of current is 'normal', it would appear. I also
have a roadster that starts just fine and that is very similar.
PaulH.
http://freespace.virgin.net/paul.hunt1/
(or if that URL doesn't work try )
(http://194.168.54.52/paul.hunt1)
-----Original Message-----
From: Tony Woodruff <tonyw@mailmedia.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: 07 November 1999 00:51
Subject: It was just an oil change.....
>But now it's so much more....
>
>I gave my 67 MGB Roadster it's first oil change (I've only owned it for 4
weeks) and got it refilled, etc.
>
>Now it won't start. When I turn the key to engage the starter it just
makes ONE click. That's all.
>
>I checked to see if I disconnected any wires and there are none hanging. I
compared the wiring to the schematic in the Haynes manual - fine. Battery
is putting out 12.79 volts.
>
>I loosened the starter motor thinking that perhaps the thrust-gear had
stuck in the engaged position against the flywheel. Although I haven't
fully removed the starter it is still doing the same 1-click thing.
>
>Anything you folks can think of will be most appreciated.
>
>TIA
>
>Tony Woodruff
>67 MGB
>
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