Ground wires 81 720

[81SVN20]

Hello guys I have this wire that is attached to the alternator and then to the body when this wire corroded and fell off from the body side it cause my truck to not start just click, is that wire supposed to be there.? When I replaced the entire wire and terminals at both ends alternator and body it cranks strong now but doesn't the negative wire from battery grounded on body then to the engine the only ground wire the starter needs to engage?

[Twinpilot001]

NO!!!!!!!!!  Negative wire from Batt= goes to=ENGINE!!  Make sure it is really grounded-use a lock washer (2) on the bolt securing the ground to engine!! 1 above cable & 1 below to block!!  The alt. ground  should be to block =also!!  The one alt ground is going into elect wire bundle to dash -u must always have a ground wore from  body to block also-alt neede addl. wire from it to block  too. all wires  other than battery cables are usually small wires-10/ 16 gague wires. Remember - motor mounts are rubber!! will not allow  any grounding thry engine to chassis!! :thumbup:

[datzenmike]

Some 720s have a bolt through the thick battery ground cable to the body sheet metal near the battery and then it goes to, and is bolted to the intake, to provide a ground return for the starter. In any case, the battery ground should have a connection to the body sheet metal to ground it. The alternator is grounded to the body sheet metal and this is how it is connected to the battery.... through the body.

 

The ground wire missing from the alternator shouldn't stop the starter from cranking unless the battery ground cable is not properly grounded to the engine. The ground return would then be through the alternator ground and probably the throttle cable as the engine, transmission and differential are all rubber insulated from the body.

 

 

 

I had an old Datsun 521 back in the day that didn't have a ground to the body. The battery (which are never tied down) tipped over on a turn and the positive touched the body. Current flowed from the body down the throttle cable to the grounded carb/engine block. The throttle cable got red hot and melted the plastic sheath. When it cooled it was frozen permanently at idle.