Need some help with the alternator on my boat

[blackbuick87]

The problem is its charging 16 volts by the time it gets over 1500rpm.

Its an old style alternator, with seperate posts at the bottom for an Exciter and Sensor wires. The brand name is Prestolite.

I took the alternator in to the only alternator rebuild shop in a 3 county area, and they tested it and said it was fine. So according to the Shop Manual I have I tested all the wires and they came out ok.
WTF?

The alternator is off an 1990 454 OMC King Cobra if that helps any

Since the alternator is off of a boat it costs double to do anything to it. I had a new rectifier put in 2 years ago and it was $240

I dont want to waste money on a new regulator if that isnt what I need. Thanks

 

[1ARUNEM]

Does it have any external or internal regulator.. If external, that's probably the problem..
Goodluck!!

 

[blackbuick87]

It appears to be internal. There is no removable module on the back

 

[blackbuick87]

ttt

 

[BUICK528]

hmmm

I have a 1992 Donzi Classic 22 with a 454 OMC..

mine did the same thing...

turned out it was just a loose connection in the circuit at the starter solenoid. Check all your connections, and battery terminals. Also, we had a bad battery as well, we discovered this AFTER we fixed the connection problem.

Good luck.

Jim

 

[1ARUNEM]

Jim makes a good point, a bad battery can cause an alternator to work "overtime" trying to get the battery back up..

Goodluck..

 

[blackbuick87]

Battery was brand new last year. Jim when you had the loose connection the starter still turned over fine?


I will check the connections again. Then I will probably get another regulator. Do they sell regulators only at autozone?

 

[Drew L]

Put an external meter anywhere in line to be sure it's not one of OMC's high quality guages giving you a bum reading. If you've you have already verified the proper voltage, being that high, then follow the suggestions already presented. What style battery ddo you have? regular marine or a deep cycle? Those two batteries will act differently if it has a bad cell. In marine applications as already mentioned, connections, connections, conections. Then double check them. Don't forget your grounds. A battery cble can rot from the inside out so ddon't discount that being a possibility. To check cables you can load test those similar to a battery. If you have those wing nuts on your batteries get rid of the and get the stainless 3/8's and 5/16's nuts on there. Do not, under any circumstances, put automotive parts on your boat. I do boat fire investigations, catch my drift? If there is ever a problem connected with automotive parts installed on a boat the insurance company won't pay.At this point it sounds like something othr than the alt. Good luck Drew

 

[wallyp]

Same thing went wrong with my boat, internal regulator in
alt. Bought an aftermarket alt , Modine? i think was the name.
GM single wire replacement, about half the money.

 

[wallyp]

Yes, its still a sealed marine alt. ( Drew, thought you might ask)

 

[Drew L]

Single wire marine Delco's

They are OK. I don't know why this type of alt. isn't used in the first place. Most people change to them when faced with a replacement. Those are not a problem at all. Drew

 

[blackbuick87]

I have spent all day getting part numbers for this (^(&^$&$^ thing.

I could convert to a 1 wire setup, but it needs to fit my current brackets, and I need an output for my electric choke. The current alternator has a post that gives the choke 8 volts according to the manual. WTF would it take 8 volts?

 

[Drew L]

8 volts

So it doesn't react to fast, more gradual. Off hand I don't know where you could find 8 volts elsewhere. A balast resistor or that resistance wire. A good example why not modify. In this case we end up ****ing around with it to make it work. Did you verify it's the alt. yet? Drew

 

[BUICK528]

`geez,,

take a DVOM and check the output voltage at the ALTERNATOR, then check the voltage at the battery terminals. Do this with both key on engine off, and key on engine on, then check the voltage signal to the VOLTMETER on the dash. Record the readings. If they are the same, the gauge is wacko, if they are not the same, a competent shop can check it again for volts and amp load. You MUST use a marine specific alternator cause if you don't and you have problems involving the insurance company...they will NOT pay claims, if auto parts are inctalled on a boat. Make damn sure the main post on the starter solenoid is not loose in the solenoid housing itself. This was my problem, the stud was loose *in the solenoid*, but the nut securing the cable itself was tight. There is a securing nut for the stud, and a securing nut for the cable.

J

 

[blackbuick87]

Re: `geez,,

Originally posted by BUICK528
take a DVOM and check the output voltage at the ALTERNATOR, then check the voltage at the battery terminals. Do this with both key on engine off, and key on engine on, then check the voltage signal to the VOLTMETER on the dash. Record the readings. If they are the same, the gauge is wacko, if they are not the same, a competent shop can check it again for volts and amp load. You MUST use a marine specific alternator cause if you don't and you have problems involving the insurance company...they will NOT pay claims, if auto parts are inctalled on a boat. Make damn sure the main post on the starter solenoid is not loose in the solenoid housing itself. This was my problem, the stud was loose *in the solenoid*, but the nut securing the cable itself was tight. There is a securing nut for the stud, and a securing nut for the cable.

J

I know all this, and I am smart enough to not rely on the dash gauge. The high voltage was confirmed by no less than four gauges. I spent all day yesterday just getting a part number for the alternator (NOWHERE is it listed on it).
The only loose connection was on the starter solenoid, and I could BARELY move the wire. Nevertheless I am going to try it again tomorrow, since I cant get any parts over the holiday weekend.

I FINALLY found a Prestolite distributor yesterday with a regulator, and he wont sell to me because I am not an authorized dealer

I talked to some chick at Overtons about getting a replacement, and she must have been hired yesterday, she told me to call the manufacturer to find the right alt. . Of course they are closed for the weekend
I think I am just going to torch it instead