Burnt wires from Alternator Mercury 115

'72 Merc 1150: The engine started and ran well<br />however one wire from the alternator burned in two. I noticed that the red wires from the rectifier and switch box had been hot and looked coroded. The engine ran well and started several times. What has been damaged and needs to be replaced besides the wires. How to test??<br />UPON CLOSER EXAMINATION, BOTH WIRES ARE BURNED UP TO THE STATOR. WHAT CAN CAUSE THIS FAILURE? I PLAN TO REPLACE THE STATOR AND RECTIFIER AND COOKED WIRES. ANY OTHER SUGGESTIONS???

Re: Burnt wires from Alternator Mercury 115

I sure hope your good with wirng. Replace all your bad wiring using a good terminal kit. (Its an excuse to buy one, its good to have one nearby anyways.) Seal all the connections with regular RTV or gasket maker to keep it sealed from moisture. Take some grease and coat all your exposed connections on your starter, power pack"switch box," battery terminals, ect. <br /> Since your wires had came disconnected, dont be suprised your switch box is burned up. These things are sensitive to that kind of stuff. Make sure you are getting spark to all your plugs when you fix your old wiring.

Re: Burnt wires from Alternator Mercury 115

You need to put a new stator in that engine. You cant use a butt conn. on the stator output wires. That a great way to a fire. You need to replace the stator,rectifier and check all your 12 volt cabling cean ends and tight.

Re: Burnt wires from Alternator Mercury 115

I'm curious, why would butt connectors on the stator wires start a fire??

Re: Burnt wires from Alternator Mercury 115

Ohms Law v=I/R

Re: Burnt wires from Alternator Mercury 115

Stator wire are made from silver wire. Ive never seen silver butt conn.

Re: Burnt wires from Alternator Mercury 115

You can only let the smoke out of the wire once.

Re: Burnt wires from Alternator Mercury 115

Hello<br /> if the insulation is good you can use a quality butt splice. use one with the heat shrink already on it and shrink it, dont use black tape or silicone to seal it, both will trap water, just remember anysplice at all will fail sooner or later. personally I use a snap-on terminal crimper and it gets a good crimp. dont usse the stamped steel ones. the best metod is to use a grinder and take the plastic covering from the cheap butt connectors apply flux to the wires and the metal crimp barrel. then crimp it then use the old mimi torch and solder the joint then cover it with heat shrink.<br /> good luck and keep posting

Re: Burnt wires from Alternator Mercury 115

The number one reason outboards go one fire is the charging system. The stator has output as long as the flywheel is turning. The higher the output of the stator the more chance of fire. Fire and boats dont mix. The factory doesnt recommend any splices in the charging or ignition system. How much money have you saved if you repair a stator that goes up in smoke again and you still need to put a new one on. I would let the manufature be responsible of the componet not myself. If you have a problem the insurance is going to try to find someone to blame. Its usally the last person who did service on the boat. If you need to slice a stator wire there is a problem. In most case the stator has fried itself anyways. Wires fail for a reason (over load on the smoke inside them). The other reason is The safes way to be is not smarter than the enginee who designed this stuff. Repairing componets just doubles your labor and your libility. Replace the stator its a 100 bucks.

Re: Burnt wires from Alternator Mercury 115

Higherground: Brian03 makes a lot of sense to me. And he's exercising a lot of patience in educating us on the subject of rectifiers, connections and fires. The rectifier on my 150 Mariner caught fire one day. Fortunately, my mechanic was with me (doing a trial run). We doused it quickly and disconnected the battery cable. I asked him what would cause this to happen. "A loose connection," was his immediate answer. I pay heed since. After all, the rectifier on my Mariner costs $400+ from authorized dealers!!!

Re: Burnt wires from Alternator Mercury 115

If there is a fire on a boat and there is significant damage ( value, loss of life or other property damage) there will be an investagation. If the boat was insured and there is more than 20 percent damage It will be investagated. Not by your local boat adjuster but by a fire investagator from ABYC. They will find the cause and there good. Or an out sourse fire investagator. ABYC doesnt recomend any soldering of wires because solder melts. I find boat all the time with solder joints that have failed. Use the ABYC codes and you wont have problems.

Re: Burnt wires from Alternator Mercury 115

Ohms law is E=I*R<br /><br />The only reason I see a butt splice failing is its rated current is less than the device supplying the current, or if the volage rating is less than the voltage being applied. If the connection is poor then the amount of heat dissipated in the connections would be I=E/R or the current through the connection acting as a resistor as it is not a direct short. Then watts (P)=I*E. If the bad connecting point could not disipate the heat (watts) being created it would then heat up and melt or start a fire.<br /><br />SingleShot

Re: Burnt wires from Alternator Mercury 115

Theorys great We had a boat go on fire here friday. Fuel leak and the bilge pump must have stayed on. Boat went up. Befor the fire was out there was a fire investigater there. ABYC codes again do not recommend splices. I guess if you think your smarter than the experts splice away. Insurance companys usally have a lots of Lawyers. ABYC doesnt recommend solder joints either. I would guess the reason for the codes is there have been problems with butt splices in the past that have started fires. I've seen a boat that was wired for gas engines and half way down the asssemble line it got changed to diesel engines that boat went on fire and burned half way to the water line. The cause of fire the was the wire became the fuses it wasnt wired to code. I like all my stuff and Im not giving it up bacause I used a 50 cent butt connector. Im putting a stator on if the engine needs on.

Re: Burnt wires from Alternator Mercury 115

I'm only an ME not EE.