Balky starter ground wire??? I need advice.

[RickyD]

This is about my friends boat who recently had 8 non-boaters aboard for a trip and suddenly couldn't start the port 3208 TA engine. By using a jumper from the start battery neg terminal to the negative on the rebuilt starter (rebuilt because of the start issue) he was able to start it. So after returning from the trip he created an extra, permanent type connection between the two. I'm not comfortable with this but I don't really know why. I suggested he connect it at the negative grounding buss bar. I'm also wondering why, since the starter is grounded to the engine, that this wiring is needed. Can one of you wiring geniuses help this poor under informed electrical neophyte?

 

[KnotYet]

No genius here but I'd guess that the existing engine ground had deteriorated
enough that it no longer could pass the required amps to energize the starter.
Another possible culprit would be if the rebuild had been overzealously painted.
That could have impeded the metal to metal connection from the engine block.

 

[DavidM]

Some engines isolate the starter motor negative from its case and therefore the block so a separate ground wire is needed.

But more likely is that the ground wire from the battery to the block has a bad connection.

David

 

[O C Diver]

On some engines, the starter attaches to the transmission or a transmission adapter plate. As a result, the negative can be going through 2 or more pieces of cast-iron and bolts. IMO, best practice is to put the negative wire on a bolt holding the starter in place, after removing the paint where the negative will attach.

Nothing wrong with sharing negatives between engines. As for the ground (bonding system), most bonding system have too small a wire size to handle the starter cranking amps, especially a non gear reduction starter like on a 3208.

Ted