Battery terminals sparking and wire to alternator gets hot, very hot

[Stephanefortin120]

Hi, just purchased an older fiberglass inboard boat. It has a 1984 mercruiser 2.5L 120. The previous owner said everything worked when it was winterized. Got home and put a battery in and as soon as I got the wires hooked up the terminals were sparking, smoking and melting the posts. I took it off right away. looked around and found that the orange wire going from the starter to alternator was very hot and also smoking at the ends. Got a new alternator thinking it was something going on in the alternator. Installed new one with the same results. I'm baffled and not sure what to do/check next.



Also the power trim doesn't work. when I press the up or down it clicks by the motor but nothing happens. sorry I'm new at this.

 

[Stephanefortin120]

New to this! need help with electrical Battery/Alternator

HI, I just purchased an older boat with an inboard motor. It has a 1984 mercruiser 2.5L 120. previous owner (coworker) said everything worked when it was put away. put a new battery in and as soon as I hooked up the wires their was sparks and terminals got hot. Looked around a little bit more and noticed the orange wire going from alternator to starter was very hot and smoking a bit at both ends. thought it was back feeding or something through alternator so i replaced it but got the same results. Not sure what do check next. If anyone has suggestions or similar experience that would be great.


Also the power trim doesn't work, I get a click at the motor but nothing else. I figured the brushes might be dirty something in the electric motor but not sure how to take it off or go about this.

 

[alldodge]

Howdy

I would start by checking the battery connections. make sure your positive cable goes to the starter and the negative goes to the engine block.

Next before connecting the battery connect a volt meter between the pos and neg cables (battery is NOT connected). Set meter to ohms and see what you get.

If battery is smoking the alternator wire, nothing else will work. Take some pics of the starter connections

 

[CraigBarnard]

Are you sure the leads are going to the proper posts?
Sounds like a dead short of some kind.

 

[Grub54891]

My thoughts exactly^^^ Sounds like you have the leads mixed up. How many wires are going to the battery?

 

[josh_booth]

Need to fix the battery problem before diagnosing other electrical problems. I would agree that there's a dead short. Double check the cable connections first to make sure the aren't reversed. Where do the wires go from the battery? My boat has a remote battery switch up front so my positive runs forward first and then back to the starter.

 

[Stephanefortin120]

positive goes to lug on starter solenoid (also where orange wire from alternator hooks up and another big red wire), negative goes to a ground on engine block. any ideas where or what to look for for a dead short.

 

[Stephanefortin120]

Connections didn't look bad at all did notice lug was a little loose on starter where paositiv hooks up (I tightened it all and still acts up). What am I supposed to get for a reading for resistance? I'll check this tomorrow

 

[josh_booth]

You will need an ohm meter, I would start by testing with all the wires hooked up and test at the solenoid to see if it ohms out to ground. If it does go to where the rest of the boat picks up power, I'm assuming at the starter? Unhook those wires and ohm each one to see what direction to go, also ohm the starter solenoid post without any wires on it.

 

[GA_Boater]

Welcome to iBoats.

Please do not start multiple threads on the same problem. The threads have been merged and both threads had comments, which makes things difficult for all of us to follow. Thanks.

 

[josh_booth]

Not really looking for resistance, you are going to set the ohm meter to check continuity, if it's digital most will make an audible sound, an analog one will peg the needle. Basically trying to find what positive wire has continuity to ground.

 

[Stephanefortin120]

Welcome to iBoats.

Please do not start multiple threads on the same problem. The threads have been merged and both threads had comments, which makes things difficult for all of us to follow. Thanks.

sorry didn't know it posted the first time.. my computer just kept saying "working"

 

[Stephanefortin120]

Not really looking for resistance, you are going to set the ohm meter to check continuity, if it's digital most will make an audible sound, an analog one will peg the needle. Basically trying to find what positive wire has continuity to ground.

thanks josh, I'll give that a try after work tomorrow.

 

[poconojoe]

I agree that there is most likely a dead short or your wires are mixed up. Sometimes there are multiple wires connected to each battery terminal. If this is the case, connect one at a time so as to find the culprit. All it takes is for one of them to be on the wrong terminal and you have a problem. And as a side note, marine grounds are not always black like in your car, they can be yellow. So watch out for that.

 

[MH Hawker]

this may help

 

[MH Hawker]

No Title

 

[Stephanefortin120]

awesome thanks everyone replaced some wiring going to alternator and everything seems like it's working. got dark out so i'll have to try it out tomorrow make sure all volt readings are good. on a side note. anyone know if the electric motor on the trim/tilt pump can be rebuild? where would I get a rebuild kit?

 

[Alumarine]

The trim motor might just need new brushes or perhaps a wire resoldered.
You should be able to get brushes at an electric motor shop.
You can grind them down to fit the holders.

When you take the motor apart you should be able to tell if it's all rusted or not.

 

[poconojoe]

The trim motor usually has two solenoids connected to it. One for up and one for down. These solenoids commonly go bad and are very inexpensive. Usually average about $15-$20. If you're unfamiliar with these solenoids, they are basically just switched that can handle large loads. I would check the motor before removing it. From what I recall, the green wire is down trim and the other (blue, I think) is up. Hopefully others will chime in to confirm. Make sure the motor has a ground connection, then apply 12 volts to the green, then try the blue.