92 4.3L Merc Noise With Battery Cable

[esmith4]

I have a weird issue... Boat starts right up no issues. If key is on position starter is not turning. However, once engine is running boat makes an awful squealing noise as if starter is engaged. If I pull the batter cable off battery, engine runs and noise stops.

I am at at a loss... is this my ignition switch or my starter solenoid or my key switch at dash?

I ran ran the boat this way for about 15 mins until it stalled and killed battery completely.

Thanks!

Ethan

 

[Bt Doctur]

1 NEVER remove or shut of a battery switch with the motor running. a sure way to blow every fuse and electronics with over voltage. not to mention blowing the alt.
squealing is from a bad belt, a worn belt, a slppiing pully , a bad battery ,or a shorted alt

 

[esmith4]

I was testing the alternator actually when I pulled battery cables. I know it’s not belt because I tested that as well. Alternator is a possibility, but doesn’t make sense that it is directly correlated to main battery cable being connected.

 

[esmith4]

Battery is brand new as well. Alternator will keep boat running and voltage on alternator is good.

 

[Bt Doctur]

I was testing the alternator actually when I pulled battery cables.
No, you test an alt with a voltmeter
I know it’s not belt because I tested that as well.
you remove the belt to see what makes noise
Alternator is a possibility, but doesn’t make sense that it is directly correlated to main battery cable being connected.
your removing the high load from the alt and its belt

 

[esmith4]

Thanks. So even if the alternator wire is still attached to battery and I have only pulled the starter wire, you think it is belt? I didn’t pull the belt because I was afraid it would damage something. It kind of sounds like an awful high pitch squealing and the battery cable gets super hot to the touch. And like I said in original post this killed the boat and left me stranded after about 10 mins of running.

 

[achris]

High pitched squeal? And only until the battery recharges? That's the belt slipping. 100% Hot battery cable - Faulty battery, replace it.

Either the belt has glazed, replace the belt, or the pulleys are too shiny. 'Un-shine' them... Or the belt is loose, tighten it.

And I'll reiterate what BT said... NEVER remove any battery leads with the engine running, or switch batteries off. Quickest way to be replacing EVERYTHING electronic on the boat, including instruments and radios.

Chris.......

 

[Bt Doctur]

remove the belt and test run it for 5-10 seconds , it wont hurt a thing

 

[esmith4]

Thanks guys. I am glad I asked. I was told by a backyard mechanic to remove batt cables to test alternator after boat stalled and killed battery on lake.

 

[Bt Doctur]

guessing this guy also sells new alt too

 

[Scott Danforth]

lets explain what pulling the battery leads can do on a running engine. the alternator sense wire is separate from the alternator output. so pulling the battery lead causes the alternator to go to full output.... if there is no where for that current to go, with minimal load the voltage spikes to about 30 volts, every electronic piece that doesnt have serious over-voltage protection gets fried, the lights that were on may blow and the alternator internally goes into meltdown causing a spectacular blue glow then the insulation on the windings melts...

proper way to test an alternator. use a multi-meter, test battery voltage - should be about 12.4-12.6 volts if less, the battery is discharged. alternator output should be in the 13.4-14.6 volt range with a sense wire voltage below 12.6 volts. (generalized for discussion, each alternator design may vary slightly)

 

[esmith4]

My battery was just replaced less than 2 months ago.

Would a bad battery or belt have caused my boat to stop the engine running in the middle of the lake?

I appreciate yall’s help. I have been out three times and ended up stranded... the first time was the carb and the last two times is the issue that I have been discussing now. I cannot figure out what is causing the engine to stop after about 10-15 mins running and battery is discharged. My thought was alternator but this could just be a belt?

 

[thumpar]

With the battery disconnected the alternator voltage could have spiked and blown out ignition components.