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gweaver
10-03-2011, 01:42 PM
So I took the boat out for what should have been a nice cruise with the family. Started out all well and good, but about a mile from the marina, the engine just died. Tried to restart and got the characteristic sound of a dead battery trying to turn the engine over.
We were towed back to the marina and when I got the boat home, I hooked it up to a charger- battery was at 25% What this indicates to me is that the alternator isn't charging the battery. I'm going to pull the alternator and have it tested at the local AutoZone, but is there anything else I should check/do? I did give the battery terminals a scrape to remove corrosion, but what else should I be checking?

Also- if the alternator is bad, is there any reason I can't/shouldn't just replace it with an automotive alternator of similar output? Is there something special about a marine alternator? Especially since it looks like I could replace a 51A alternator with something that puts out closer to 100A.

And the obligatory 'towing back to port' image.
https://lh4.googleusercontent.com/-EGSeesnqhWQ/TokAhDdWUGI/AAAAAAAAAWg/q0VHrgf5eXM/s720/PA020075.JPG

Yup. Sea kayakers. They helped us for about 1/4 mile, then we hailed a boat heading out and they were nice enough to turn around and pull us the remaining 1/2 mile to the ramp.

Thanks for any suggestions.

Greg

CantRepeat
10-03-2011, 01:49 PM
Yes there is a difference between a car and boat alt. Marine units are designed to contain sparks and are coast guard approved for boats.

Call a dealer or skidim.com.

thatsmrmastercraft
10-03-2011, 01:50 PM
1. You can't us an automotive alternator as a marine alternator has a spark arrestor on it to keep your boat from blowing up.

2. You need to clean all the connections of the cable in the starting circuit including the connections at the starter, solenoid and the ground at the block. Brush them all with a wire brush and be sure to not miss anything. A goo looking connection may not do a good job.

3. You could also have a problem with your battery. I would charge that and take that with you to be tested.

gweaver
10-03-2011, 04:32 PM
Cool.

I'll pull the alternator this week and run a charge on the battery and get them both checked. I'll also check electrical connections. See what I can find.
Thanks for the advice.
G

gweaver
10-03-2011, 06:54 PM
A related question- any idea if the stock alternator is internally regulated? I was talking to a friend and he said that I should also check the voltage regulator, if it's external. If it's internal, I assume it would be tested as part of whatever AutoZone would do.
G

thatsmrmastercraft
10-03-2011, 09:30 PM
Should have an internal voltage regulator. Your profile says 88 Prostar........that what we are talking about here?

gweaver
10-03-2011, 09:44 PM
Yup. It's an 88. Tho given that it just started raining here, I suppose some of the sense of urgency has passed. Still want to address the problem, but I don't see me getting out on the water this weekend. Weather's not supposed to change any time soon. :(
G

gweaver
10-05-2011, 10:47 AM
So a bit of an update- started the engine yesterday to flush the engine (wasn't able to get it running Sunday when we got off the river). Let it idle for a while, then pulled the positive terminal off the battery. Engine kept running with no hiccups, but the depth gauge started squawking and the voltmeter started bouncing around. Left the positive lead off for about 30 seconds with no change to the engine. Put it back on the battery and the depth gauge and voltmeter sorted themselves out.
This would lead me to believe the alternator is good and perhaps the problem is with the battery?
Thoughts?
Thanks,
G

Matt@semmergroup.com
10-05-2011, 11:49 AM
I'd bring the whole boat on the trailer to a local automotive repair shop. With the engine running they can use a meter to determine if the system is charging. If it's not it could be the alternator or a bad connection. If it is charging then it's probably a problem with the battery which could also be a bad connection. It's also possible that a short in the starter is drawing the charge.

I wouldn't want to remove the alternator and battery if I didn't need to. The shop should charge like $20 and I personally would have no concern about running the engine "dry" for a couple minutes, just watch the temp gauge.



matt

thatsmrmastercraft
10-05-2011, 12:23 PM
So a bit of an update- started the engine yesterday to flush the engine (wasn't able to get it running Sunday when we got off the river). Let it idle for a while, then pulled the positive terminal off the battery. Engine kept running with no hiccups, but the depth gauge started squawking and the voltmeter started bouncing around. Left the positive lead off for about 30 seconds with no change to the engine. Put it back on the battery and the depth gauge and voltmeter sorted themselves out.
This would lead me to believe the alternator is good and perhaps the problem is with the battery?
Thoughts?
Thanks,
G

Perhaps? Never tested a system in that manner. Much better would be to be using a voltmeter to see what your battery voltage is like at rest and with the engine running. If you don't have a DVOM digital volt/ohm-meter, they are inexpensive and worth having.

gweaver
10-09-2011, 02:52 AM
I have a DVM. Will hook it up tomorrow morning and check voltages. Will still probably take the alt. and battery to be tested. I'll also use the ammeter setting to check for any current draw when sitting.
I'll see how it goes. :)
G

gweaver
10-10-2011, 04:12 PM
Update: got battery and alternator out to have them tested. Battery tests good, but since the alternator is a 1-wire unit and there's no automotive cross reference, the local auto parts places couldn't test it. No big deal, just need to mount it back up and take a voltage reading across the battery terminals with the engine off and with it running to see if the alternator is producing voltage. The only problem is that the alternator mounting bolt sheared off in the block. :mad:
Any suggestions on how to remove it? I've read threads about easy-outs and about left-hand drills, both methods have advantages and disadvantages. Before I go out and invest in either of the above tools, I'd appreciate any experience-based insight you folks may have.

G

thatsmrmastercraft
10-10-2011, 04:21 PM
Update: got battery and alternator out to have them tested. Battery tests good, but since the alternator is a 1-wire unit and there's no automotive cross reference, the local auto parts places couldn't test it. No big deal, just need to mount it back up and take a voltage reading across the battery terminals with the engine off and with it running to see if the alternator is producing voltage. The only problem is that the alternator mounting bolt sheared off in the block. :mad:
Any suggestions on how to remove it? I've read threads about easy-outs and about left-hand drills, both methods have advantages and disadvantages. Before I go out and invest in either of the above tools, I'd appreciate any experience-based insight you folks may have.

G

A picture would be good here, since how the remaining face looks may determine the best method of removal.

gweaver
10-10-2011, 05:06 PM
It's raining here and the boat is under a cover in the driveway. If it clears up tomorrow, I'll try to take one. As I recall, the bolt broke off about 1/4 - 3/8" down the hole.

thatsmrmastercraft
10-10-2011, 05:14 PM
It's raining here and the boat is under a cover in the driveway. If it clears up tomorrow, I'll try to take one. As I recall, the bolt broke off about 1/4 - 3/8" down the hole.

Given the description, I would be inclined to drill it out. I have never had good luck with an EZ-out, but I know people who swear by them. I just swear at them. My method is to get a hole started with a small bit (hopefully) in the center of the bolt, then just go up one bit size at a time until there is very little left, then re-tap. Or, more likely, go one size over and tap a fresh hole.

gweaver
10-10-2011, 08:56 PM
OK- I'll work on finding some left-hand drill bits. With any luck I'll be able to get this done this weekend. Thanks for the suggestion.
G

gweaver
10-16-2011, 11:12 PM
Victory!! Borrowed some left-hand bits from a friend, after a little drilling the broken bolt came right out. Took the alternator to NAPA to have it checked but their tester wasn't working. Will try to get it over to them later this week after they've had a chance to fix their machine. Worst case I just bolt the alternator back up and use a DVM to see if it's putting out voltage at idle. Slowly making progress on this. :)
G

thatsmrmastercraft
10-16-2011, 11:55 PM
Victory!! Borrowed some left-hand bits from a friend, after a little drilling the broken bolt came right out. Took the alternator to NAPA to have it checked but their tester wasn't working. Will try to get it over to them later this week after they've had a chance to fix their machine. Worst case I just bolt the alternator back up and use a DVM to see if it's putting out voltage at idle. Slowly making progress on this. :)
G

Job well done.:toast:

gweaver
10-25-2011, 02:00 AM
Anyone have any idea about an automotive cross-reference for the alternator for an 88 Prostar? I'm trying to get my alternator tested but the three places I've been (NAPA, Autozone, O'Reilly) have all been unable to test it. Apparently their testers need a model number to be entered prior to testing. I've been unable to find a part number or similar automotive alternator. (the testers just give a 'pass' or 'fail' result based on measured output compared to stated output). NAPA did run a test on it, but it failed based on specs for a similar, but not identical alternator.

I know I can go the DVM route, but for some reason, now I'm obsessed with finding a part interchange number.
G