5.7 GXI-H engine. Alternator problem ?

[1994almeida]

Volvo Penta 5.7 GXI-H engine.
After the engine starts, the voltmeter starts to indicate 12.5 Volts and then the voltage starts to rise very slowly.
If I accelerate the engine beyond 1100 rpm the alternator belt starts to squeak.
Sounds like the alternator is stuck and making the belt squeal.
Only after 3 minutes, or more, with the engine running, does the voltmeter reach 14 Volts and from then, is no more squeaking and the engine operates normally.
Batteries are new and charged. With the engine stopped, they indicate 12.8 volts on the boat's voltmeter.
What will be the problem?
Thank you very much

 

[alldodge]

Might need a new belt or belt tension is off

Boat voltmeters are not very accurate, check Bats with hand held digital meter

Remove belt and spin the ALT by hand several times feel for roughness and listen

ALT's normally don't start producing full voltage until the RPM's increase above 1500. This is also a reason most (not all) MPI's will rev up real quick after starting before idling down to spec.

 

[1994almeida]

Thanks for the answer
The belt is new and I don't see any tensioner on this engine.
The problem is the hissing sound until the voltmeter reaches 14 volts.
I will do as suggested.

 

[alldodge]

Every belt has a means of adjusting the tension. Can be a unit like the ALT or a idler pully

 

[Scott Danforth]

looks like a spring loaded idler

 

[1994almeida]

Hello
I saw now that the small plug that connects to the alternator has only one electrical cable.
There is another electrical cable, black, that connects to the body of the alternator, perhaps it is ground.
Could my problem be the lack of that cable?
Or is everything ok because the ground cable, black, connected to the body of the alternator, replaced the cable that is missing from the plug?
Thanks

 

[alldodge]

It's correct, VP uses only one excite lead which turns the ALT on

 

[Donald0039]

If there is only one wire beyond ground to the alternator then it's a "hot rod" style and is self exciting. They need an initial rev in RPM beyond idle before they will charge the battery. After that they charge at any RPM although better higher RPM.

A normal alternator (internal regulator) has charging output on a large wire, excite (only power with key on) smaller wire, and sense, also on a smaller wire.

 

[Lou C]

Isn't there also an S terminal (Voltage sense)? I know the older Volvo set ups had the Excite, Sense and Voltage output terminals, and on some the Sense was simply connected to the Voltage output terminal with a short wire.

 

[1994almeida]

Thanks for the answers.
There is only a thick red electrical wire, which I assume will charge the battery, a black electrical wire connected to the alternator body and a thin wire that connects to the plug.
The problem is, if right after starting the engine, I increase the rpm the belt squeaks.
What I do is wait 3 to 4 minutes at 1100 rpm and the voltage slowly rises. When it reaches 13.5 Volts, the belt no longer squeaks.

 

[alldodge]

Your pic in post 6, I'm seeing a connection down near the bottom with one small wire on it and covered in the plastic wrap.

ALT on far right of pic is a terminal with I think a "P" on it

 

[flashback]

Your pic in post 6, I'm seeing a connection down near the bottom with one small wire on it and covered in the plastic wrap.

ALT on far right of pic is a terminal with I think a "P" on it

Yeah I see a spade terminal , what is that for?

 

[alldodge]

Might be for a purple wire if the lower wire doesn't go to ALT. What is stamped on it?

 

[flashback]

I can't tell and don't know what's in the sheath.. you think it's an ignition terminal?

 

[alldodge]

I don't know, would need to be there to look

 

[1994almeida]

The spade terminal has the letter P and nothing is connected to it.
The alternator only has 3 electrical wires, the negative, the supply, and another connected to the lower plastic wrap.
Thanks

 

[alldodge]

With 3 wires then terminal P is not needed and the ALT is wired like most VP motors

 

[1994almeida]

Problem solved.
The alternator belt was incorrectly mounted.

 

[QBhoy]

Thanks for the answer
The belt is new and I don't see any tensioner on this engine.
The problem is the hissing sound until the voltmeter reaches 14 volts.
I will do as suggested.

I’m going to have a guess that it’s the IAC making the hissing and trying to control the idle rpm under warm up condition. Lots of power is needing replenished after the act of cranking her.

 

[1994almeida]

What made the noise was the alternator belt.
The drive belt route was wrong.
The automatic tensioner did not apply enough pressure, so the belt had a lot of slack, it slipped and made noise.