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MG MGB Technical - Starting issue

Hey good folks, I was stranded on a trip, by a no start condition, while at the Tanglewood show. When moving the ignition key to the start position, NOTHING happened! I got a couple of passing teenagers to push the car and it started fine. Had no issues for the next two days.

In my head there are 4 possible areas of concern, starter solinoid, starter relay, wire/connectors and ignition switch. The switch is about 1 Moss one year old, the starter is an 18 month old rebuild and the relay is original. Al wires and terminals seem OK.

Has anyone had a bad experiance with the starter relay? Thanks, Tom
Thomas McNamara

The starter changed in the cars life, which one do you have? My early car has the Bendix and a separate solenoid this changed I think in 1968.
Stan Best

Sounds like you may have got the starter ring and solenoid pinion momentarily jammed? Is this the was it used to occur? Sometimes a clout with a hammer would release, then one could start normally. The fact that it was all normal for the next 2 days after suggests something like this? Mike
J.M. Doust

Tom-
Wiring, especially bullet sleeves under steering column. N,WR, W
Switch
Starter
Relay - never had a bad one. Check connections there though.

FRM
FR Millmore

You should always look at the ignition warning light under these conditions. If it dims right down either the battery is flat or there is a bad connection in the battery earth or the 12v cable to the solenoid. If it doesn't dim at all power isn't being applied to the solenoid. If it dims very slightly power is probably being applied to the solenoid, but it isn't applying power to the starter motor. Also listen to see if you can hear the relay (1970 on) click, the solenoid clonk, or anything else, that will tell you which part of the circuit to investigate. With the earlier inertia starters (Mk1 cars) the starter could also be jammed, but that usually gives an audible clonk as it does so, engaging 4th and rocking the car back and fore should release it.
PaulH Solihull

Thanks guys,for all ideas. When I say I got nothing at the start position, I mean nothing! I did not hear the solinoid click at all. (Can you hear the relay?) I will check under the dash tonight for connections. BTW, I turned the lights on and they showed no dimming on the "dead strart". I do however, have a headlight relay. What think? Regards, Tom
Thomas McNamara

I had a really worn solenoid which would click but not make contact. When I took it apart the contacts were completely worn and the little spring on the plunger was broken. A new one fixed it. The symptom was hearing it clunk in but no power to the starter. Just CLICK!

When it happens again, and I find these things always do no matter hard hard you try to convince yourself it was a one off, have a multimeter handy to measure the voltage at various points along the circuit starting at the switch, then the relay then solenoid.

Paul's suggestion with the ignition light is the best place to start. That one little light is very handy!
Simon Jansen

The year of the car would be helpful, we still don't know whether you have a relay, remote or attached solenoid, or what.

Yes you should hear the relay (if you have one), but on an LHD you may need someone else to turn the key or listen unless you can turn the key with your head under the bonnet. Headlight relay is irrelevant, unless you are thinking of using it as a test substitute.

If the light isn't dimming at all then the chances are you are not even powering the solenoid, let alone the starter. So if you have a relay it could be that, or the ignition switch in either case, or associated wiring and connections for each.
PaulH Solihull

Thanks again, the car is a 1973 model. It has a relay mounted by the fuse box. I sometimes use the relay connection tabs to turn the engine over while working under the hood. I am starting to think it is the year old ignition switch(?) but it has started 40 or 50 times since the incedent. Intermittants are the bane of my MG life. I'll try to park on a slope from now until it fails again, which I am sure it will. Tom

Thomas McNamara

For a 73 that relay is the starter relay, so whether that clicks or not when the problem occurs is crucial.
PaulH Solihull

This thread was discussed between 21/06/2011 and 24/06/2011

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