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MG MGB GT V8 Factory Originals Technical - Grounding problem

question for all the conversion guru's out there, this one baffels me. my car, 1978 b rdstr with gm 3.4l v6, complete with fuel injection system, t5 transmission, recently installed gm rear end with 3.4 ratio. went to start the car 3 days ago and nothing happened when i turned the key except there was a very strong burning smell. shut off the key and looked under the hood thinking wiring harness might be on fire, nothing. went back and tried key again and the car started, went to move and the clutch pedal went to the floor, looked under the car and pool of fluid was dripping from the mccloed TO bearing cables. after inspection the rear stainless steel brake line is burned on both ends and the mccleod appears to have had the o rings burned out of it . mechanic says it appears to be a grounding problem, i have a newer battery and last winter i installed a new braided cable for the ground strap, this appears intact with good connections, anyone else seen anything like this? any suggestions?, thanks, safety faster, jim
j.a.madson

The rubber motor mounts electrically isolate the motor from the battery so a good ground strap is require to bridge this electrical gap. The car will generally run without a good ground by relaying of poor grounds such as the accelerator and heater cables and those cables can become very hot. The plastic covering on accelerator cables often become brittle and crack from the heat with so much current running through them, you have suffered uncommon problems with the o-rings melting. To avoid these problems I use a ground strap that connects from one side of the rubber motor mount to the other side and an additional smaller ground from the alternator to the body.

Hope it’s not too much of a problem to replace your o-rings.
George Champion

Yes, I had a ground lead that looked clean and perfect, but the engine turned slowly and the choke cable got hot. Replacing the lead cured the problem. I guess because the starter draws a high current even a low resistance will mean the current chooses another path.

Phil
Philip Shingler

Bad Luck. The ground strap has been a problem throughout the life of the B - most of us who have had problems fit a second strap where we can keep an eye on it.
Roger

My V8 has started much snappier since I fitted two earth straps, there are several convenient positions eg bolts and holes around the engine, notably on the cylnder head castings, and attached to the bolts holding the clutch housing to the engine.

Mike
Michael barnfather

That's one problem you'll never have again
Roger

Why don't you just clean up the original strap?
Paul Hunt

This thread was discussed between 08/07/2002 and 11/07/2002

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