Electrical question, '80 50HP Merc

[Dee Rambin]

I was doing some electrical testing on my motor this weekend to try and find out why the starter motor barely turns the motor over and gets very hot. I read on here that 3 out of 5 starter motors get replaced when there is actually some other problem. <br /><br />I connected the positive lead of my volt meter to the battery pos terminal and "accidently" learned that I had 12.6 volts registering with the negative lead of the meter touching the hull (aluminum boat). <br /><br />The hull isn't supposed to be grounded is it? I have a shorted ground wire to the hull somewhere in the wiring right?<br /><br />Thanks in advance for any light you might be able to shed on this or the starter issue.......Deek

 

[Nikko]

Re: Electrical question, '80 50HP Merc

I can double check my '80 50HP, but I don't believe the grounding side of the circuit is isolated. By this I mean that I believe the entire chassis of the engine is referenced to ground and if this is the case, and the motor is touching your aluminum hull at any point, the hull too will become referenced to the same ground. Which means the reading you got was normal.<br /><br />If in fact the GND side of the circuit is supposed to be isolated then I'm all wet.<br /><br />My $0.02 (CDN)<br />Rob