Voltage drops to 6 and everything heats up when engine is warm

[98LarsonGM57]

So I have a 98 5.7GS; just put a new longblock in and got her in the water yesterday.

Before I put her in she idled in the driveway for an hour no problems.

I put her in and we ran about 5-6 miles at moderate speeds then the engine cut out and would not restart.

About an hour later I tried it - she fired and ran about for a few minuites - same thing.

When this happens the voltage coming into the altenator is 12 volts - the voltage coming out is 6 volts, the atl is hot, the back of the ignition switch is hot as h*ll, the back of the voltmeter is hot; and the ignition fuse got so hot the plastic melted.

Does this seem like concidential timing and the voltage regulator is going out? it is another wiring issue angering it?

note when this is going on there is no spark and the voltage meter on the dash is reading under 10 - when everything cools off ~ 1 hour sitting the voltage meter on the dash pops back to 12 and the engine will immedieatly start. HELP

The alt is a volvo/ mando 3856600
EDIT

 

[98LarsonGM57]

Re: Voltage drops to 6 and everything heats up when engine is warm

So the boat sat over night and I just checked it - its cold and still has 12 coming into the alt and 6 going out. I have ordered a new alt/regulator as it seems clearly shot but am concerned that there could be short somewhere else that caused this to burn up - especially given how hot everything got - any ideas would be really welcome - I am in this deep and do not want to ruin another altenator....
btw - it is a 1998 Larson SSEI - I have had it for 10 years - everything but the longblock got switched over to the new (used) motor - the motor got wrecked when the manifolds leaked and salt water sat in the block and it siezed - yeah yeah I know - fresh water cooling system, should not have let it sit, etc.

Thanks!

 

[Don S]

Re: Voltage drops to 6 and everything heats up when engine is warm

For the ign. switch and volt meter to get hot like that, you have some serious wiring problems. Something hooked up wrong.
What was the full model number of your original engine, or the serial number. I'll see if I can find a wiring diagram.

 

[98LarsonGM57]

Re: Voltage drops to 6 and everything heats up when engine is warm

Now that I need it I cannot find the VIN!! But I have the wiring diagram attached.

It is a Volvo 5.7GS - not sure the rest of it - but they seem the same and this diagram is accurate.

Note: when we switched the logblock we did not unhook any of the electrical from the accessories or senders - I just unbolted the excessories all togather and unpluged the main harness - the only exception to this was the lead to the carb and the leads on the starter

 

[98LarsonGM57]

Re: Voltage drops to 6 and everything heats up when engine is warm

Also note - when it was running - it was running awesome - tons of power and everything seemed to work correctly

 

[Don S]

Re: Voltage drops to 6 and everything heats up when engine is warm

Somethings not right, and I wouldn't want to venture a guess as to what it would be.

 

[98LarsonGM57]

Re: Voltage drops to 6 and everything heats up when engine is warm

Another thought - I put a new starter in it - last one was a 3 wire - this one is a two wire - so I left the gray wire off - but I have run other two wire starters before on it with no problem - not sure what the grey wire is for..??

 

[Don S]

Re: Voltage drops to 6 and everything heats up when engine is warm

No gray wire going to the starter. If you have a 2 wire starter (assuming you are referring to the small terminals) then it sounds like you used an automotive starter not a marine starter. That means you have an explosion hazard.

It may be that gray wire is faded purple. It goes to the ignition coil to put full cranking voltage to the coil during cranking.