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MG MGB Technical - Starter won't quit

I searched the archises to no avail, I'm sure this has come up before. I got a '77 B that when the starter is engaged, it wont stop. even with the key off and out. I've even unplugged the ignition switch harness from and the starter keeps spinning away. Any ideas? Sorry if this is a repeat that might be tucked away somewhere in the archives.
Doug Martin

Same thing happened to me. It had something to do with a resistor up in the dash behind the radio on the passenger side. While the starter is still going, try unplugging one of the two wires from the brake pressure failure switch on the bottom of the brake master cylinder. If the starter disengages, you know what your problem is. I'd give you the technical terms for everything, and the colors of the wires you need to trace down, but I don't remember all the specifics. This will get you going in the right direction.

Good luck!
Justin
Justin

Hi Doug

There are several causes I can think of. One is that the starter solenoid is getting stuck and likely your problem. If it happens only when you try to start the car then it likely sticks until it frees with time or the vibration of the engine.

Another that happened to me on my 74 is the wiring from the starter relay shorted to chassis. The wire goes down the fender on the passenger side. Toward the bottom the insulation was rubbed off by the chassis U channel and caused an intermittent short to chassis. This caused the starter to run during the most unexpected times including when running down the highway or when the engine was shaking when the ignition is turned off.

werner
Werner

Take a look at the connectors on the solenoid. With the battery disconnected, try cleaning these up (ensuring good contact with the spade connectors AND that no bare wires are exposed so as to rub against one another). It turned out that when I experienced something similar a couple of years back, a PO had done a shoddy soldering job (one of the spade connectors had previously broken off) allowing intermittent contact between either the two wires to the normal spade connector positions (ignition & 12V line for the ballasted ignition) OR one of them to make contact with the lower nut that attaches to the alternator/battery connections. Clean everything up in this area, making sure everything's connected correctly and you'll probably find the problem goes away. If not, a new solenoid is readily available and easy to replace (if you don't mind being under the car for a while).

Barry
Barry Kindig

This thread was discussed on 02/02/2003

MG MGB Technical index

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