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ukdent
05-04-2012, 04:05 PM
Hey guys I have been lurking around trying to learn as much as possible, However today when I began to instal a new alternator in my 2000 Mastercraft Maristar 210 vrs with LTR motor, i ran in a snag. I am upgrading for the standard 51A to a 110A. I was told when I bought the new alternator it would be a direct bolt in and it should be close but they are slightly different.

Pictures of both old and new alternator are below, any guidance on where to hook the purple exc wire would be greatly appreciated.


I will also be upgrading to 4g wire, but i quick question about the 40a fuse. Will i need to change that or just run the positive from the alternator straight to the pos on the starter solenoid?

Thanks for all your help, Sorry its probably an easy question, but for me I dont want to risk screwing something up, so the opinions of those far more experience is requested.

Thanks..
Oh yea top 5 images are old one and 6th is new one

petermegan
05-04-2012, 05:24 PM
I have come across newer alternator's that don't need an exciter wire. I would just give the supplier a push for a wiring diagram, otherwise try it without it may be fine.

rwoznock
06-23-2012, 07:50 PM
Sorry to jack this thread but I have the same problem. I have a 96 maristar with the Indmar 5.7 in it. Been plagued by questionable starts after playing the stereo. Finally a few days ago it stopped working and both batteries went dead. I replaced the alternator with a new replacement which has terminals in the same spots as the old one. I wired the new one identical and fired it up. The volt meter said 8 volts and I suspected something was wrong. I shut the key off but the motor kept running. I turned the key off and pulled off the purple wire and it shut off. I left it off and restarted it and it worked fine. I ran it around the lake for over an hour, and it seems to be working fine. Now volt meter goes to nearly 14 volts, engine starts no problem, and it shuts off. There were no markings on the terminal where the old one or the new one had the purple wire attached. I also looked online to find a diagram for this alternator but can't find one. If anyone can shed any light on this wire, please let me know. Thanks in advance!

Philscbx
06-23-2012, 08:08 PM
If anyone can shed any light on this wire, please let me know. Thanks in advance!With the Purple disconnected - key on - is there 12v on it?
Key off "0" volts.

rwoznock
06-24-2012, 06:09 AM
That I didn't check but I will today.

mikeg205
06-24-2012, 11:30 AM
I agree, ask for the wiring diagram. Self-exciting alternator?

I would contact presto...

Here's the contact.



Mark Timerman
mtimerman@prestolite.com
Tech service line: 866-288-9853

rwoznock
06-24-2012, 12:35 PM
It does have 12to volts to it with the key on.

rwoznock
06-24-2012, 12:36 PM
It's a Arco alternator but thanks!

JimN
06-24-2012, 02:03 PM
Sorry to jack this thread but I have the same problem. I have a 96 maristar with the Indmar 5.7 in it. Been plagued by questionable starts after playing the stereo. Finally a few days ago it stopped working and both batteries went dead. I replaced the alternator with a new replacement which has terminals in the same spots as the old one. I wired the new one identical and fired it up. The volt meter said 8 volts and I suspected something was wrong. I shut the key off but the motor kept running. I turned the key off and pulled off the purple wire and it shut off. I left it off and restarted it and it worked fine. I ran it around the lake for over an hour, and it seems to be working fine. Now volt meter goes to nearly 14 volts, engine starts no problem, and it shuts off. There were no markings on the terminal where the old one or the new one had the purple wire attached. I also looked online to find a diagram for this alternator but can't find one. If anyone can shed any light on this wire, please let me know. Thanks in advance!

If the last alternator was the OEM, it had a terminal marked 'EXC' and that's where the purple wire went. This new one isn't an exact replacement and if you didn't increase the current substantially, I don't understand why you didn't just have the one one rebuilt to the max current that can be stuffed into that case. It completely avoids any confusion about which wires go where and it IS a direct bolt-on.

Running the stereo to the point of killing the batteries and you suspect the alternator? What seems logical about that? Killing the batteries and re-starting it when they're in that state is how alternators die. Recharging dead batteries aren't what an alternator is designed for- they're made to recharge the batteries after cranking the engine. Also, idling the engine while trying to recharge batteries doesn't work. It doesn't fully recharge them and it kills the voltage regulator pretty quickly. The alternator doesn't hit 14+VDC until about 2000RPM. At idle, it's usually about 12-13VDC, which is normal for that engine speed, but recharging at low RPM is not how the electrical system was designed to work.

FYI- if you need to jump-start an engine, shut the donor engine off before cranking and especially if the battery is stone dead. A dead battery is a huge load on an alternator as it is but these starters draw between 175-350Amps when cranking, depending on the age/condition of the starter, the voltage and how hard it is to physically turn the engine over. The battery does supply some additional current but the starter takes a major hit when it has to support a starter. If you jumped an engine and had to replace the alternator a short time after, this is the reason.

mc190
07-01-2012, 11:56 AM
Any advice on where to get one rebuilt?

Philscbx
07-01-2012, 03:54 PM
FYI- if you need to jump-start an engine, shut the donor engine off before cranking and especially if the battery is stone dead.

A dead battery is a huge load on an alternator Right - the best way to jump a dead one connected -

Can leave donor engine source running -
for twenty minutes so charging system is assisting the draw on the good battery.
Never attempt to start a dead ship or vehicle while in jump mode the second they get connected.

This it the number one killer of systems.
Especially if light weight cables are used - which is 97% of the case.

Hooking up then hitting starter of dead source immediately is just too severe a load on donor alternator.
It's trying to charge it's own & the dead - it doesn't need the starter added.

I use custom made welding cables with Anderson disconnects.
Made them 20 yrs ago. If needed - extension can insert in seconds.

When charging tapers off - now the connected can be started w/o the hard hit to donor system, or remove cables - because it's own battery is ready.

If started then disconnected - the dead one is still dead - and would never start if it killed.
Now alternator of dead ship has difficult chore - not made to do. If truly Dead.
If only just low enough to slow crank - this will recover quickly sitting for 2-3 minutes connected.

JimN
07-01-2012, 06:47 PM
Right - the best way to jump a dead one connected -

Can leave donor engine source running -
for twenty minutes so charging system is assisting the draw on the good battery.
Never attempt to start a dead ship or vehicle while in jump mode the second they get connected.

This it the number one killer of systems.
Especially if light weight cables are used - which is 97% of the case.

Hooking up then hitting starter of dead source immediately is just too severe a load on donor alternator.
It's trying to charge it's own & the dead - it doesn't need the starter added.

I use custom made welding cables with Anderson disconnects.
Made them 20 yrs ago. If needed - extension can insert in seconds.

When charging tapers off - now the connected can be started w/o the hard hit to donor system, or remove cables - because it's own battery is ready.

If started then disconnected - the dead one is still dead - and would never start if it killed.
Now alternator of dead ship has difficult chore - not made to do. If truly Dead.
If only just low enough to slow crank - this will recover quickly sitting for 2-3 minutes connected.

Delete, please.

Philscbx
07-01-2012, 07:01 PM
Delete, please.For what reason.
And what was missed

JimN
07-01-2012, 07:19 PM
For what reason.
And what was missed

I posted something that was redundant- I wasn't asking for your post to be removed. I had quoted you and my comments were unnecessary.

Philscbx
07-01-2012, 07:22 PM
I posted something that was redundant- I wasn't asking for your post to be removed. I had quoted you and my comments were unnecessary.LLol - hate when that happens - I have a track pad on laptop - it gets me in trouble a lot.
It grabs files and drops them unknown at will.
Cheers