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MG MGB Technical - Early MGB Starter Solenoid

Hi, I'm usually on the mg td/TF Forum but I need some help from the early (62-65) MGB gurus....

A few years ago I put an early (62-62) MGB starter solenoid on my TD, with a push button start switch on the dash. While working on reinstalling my air cleaner after a carb swap, I had some contact and sparking with a wrench (forgot to disconnect battery). Today, as soon as battery power is restored by tightening my quick disconnect, the car tries to crank (key off). Only way to stop it, is to kill the battery with the quick disconnect.

I assume I toasted the relay when I got the sparking, or is there a different issue?

Any info appreciated.

Larry

L Karpman

The solenoid shouldn't have welded itself, it is designed to power the starter after all. What was shorted together? Are you sure the operate terminal of the solenoid hasn't been knocked against the battery terminal? Or your push-button switch or wiring isn't at fault? Easy enough to check the latter by disconnecting it at the solenoid and connecting the battery.
Paul Hunt

Paul: With the wiring from the starter switch removed from the solenoid, if I connect the hot cable from the battery to the top post (as normal) and the starter cable to the bottom post (as normal) the solenoid turns the starter without any other actions on my part. Perhaps some other internal solenoid wiring at fault.

Thanks for the input

Larry
L Karpman

Indeed. If you disconnected the cable between the starter and the solenoid and *then* connect the battery, if you hear a click (currently being drowned out by the starter bursting into life) that shows the operate terminal for the solenoid winding is in contact with the battery terminal somewhere.

If no click, but battery voltage appears on the output termional of the solenoid, then the solenoid contacts are welded or shorted together.

Either may well mean replacement of the solenoid, but it would be interesting to know, and if the former maybe the problem is external and hence removable.
Paul Hunt

This thread was discussed between 31/03/2009 and 02/04/2009

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