Recently I had parked my 74 MGB in the local shopping center parking lot.
Upon returning I noticed the car had moved slightly forward up against a
concrete barricade. Strange! When I pressed in on the clutch to start the
car, it moved back and the engine turned over, all before I turned the key.
Puzzled, I tried to start the car, but nothing happened - no starter
operation. Popping open the bonnet I could detect the faint smell of smoked
electrical wiring! After getting the B push-started and arriving home, I
started trouble-shooting. I disconnected the small white wire to the starter
solenoid and rigged up a wire so I could see if the solenoid was getting 12
volts when I turned the key.
My multi-meter showed 12 volts to the starter solenoid even without the key
in the ignition! I then disconnected the solenoid wire at the starter relay
end, thinking that maybe the relay had an internal short. Still 12 volts at
the solenoid end of the wire, which was now disconnected from anything at
both ends! About this time, before climbing under the jack-stands again, I
disconnected the battery.
Really puzzled, I started unwrapping the wire bundle into which the solenoid
disappeared, starting from the solenoid end. About an inch into the bundle,
I found chaffing on both the solenoid wire and one of the 12 volt lines that
taps off the starter and that is live at all times. The culprit was the
mounting bracket for the clutch hydraulic line. The wire bundle was resting
against this bracket, and even though the wire bundle wrapping material
apeared only slightly frayed, the insulation had completely worn off the
wires inside.
The fix was easy - clipped off the frayed wires, re-spliced with some butt
connectors. Wrapped the area with electrical tape - bought some plastic wire
bundle stuff at the hardware store and routed the bundle away from the clutch
line bracket. The starter was in fact fried, so a rebuilt one was installed.
The lesson is scary. I had been under this car several times in the past few
weeks, changing brakes, oil filter, and other routine maintenance. If I had
bumped the wire bundle I could have activated the short. I normally place
the car in gear, brakes on, with chocks under a rear wheel when jacking. The
car still could have jumped forward off the jackstands with me underneath.
Usually I do not disconnect the battery since that causes my new radio to
zeroize and I have to reporgram my favorite stations and reset the radio's
clock.
Next time you are under your MGB, after either disconnecting the battery or
at least putting gear shift in neutral, unwrap a few inches of this wire
bundle and check for chaffing at the point adjacent to the bracket where the
clutch hydraulic line is attached.
I would like to know if anyone else finds the same problem - just curious.
Also, I sent in the above text as a candidate for the next issue of Moss
Motoring.
Ken Swaggart (kswaggart@aol.com)
74 MGB Roadster
88 Jag XJS
85 Ford Wagon (still runs great)
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