Stator fried, what to use for insulation?

rotus623

All topics are on topic as far as I'm concerned. That little 4hp longshaft is running like a sewing machine!! I cleaned all the water passages, new gaskets, ignition system, carb, fuel pump, and water pump. Sooooooooo reliable!!!

rotus623

Okay Jim, I finally got my scotch 27 in, and re-wired the stator. Now keep a few things in mind. What I did was keep the nylon because I felt like it held the wires on tight, and I just wrapped them with scotch 27. See photos. Also, when I rewound the coils, I got them as tight as I could, but the wires didnt wrap as neat tight as they did from the factory. How important is this? I have plenty more wire if I need to just bite the bullet and rewind it. I made sure to count the wraps, and follow the wrap pattern. Thanks for your input and support!!

jim hardy

That looks to me like an excellent job.

Tightness of wraps will not make much electrical difference at all.
Biggest reason for tight wrap is to keep wires from vibrating against each other and wearing through their varnish insulation. This is what - a ten amp alternator? Not very much force on them. I believe you'll be fine.



Check it with ohm-meter to make sure nothing's shorted to metal
then try it out .

Nice looking work !
Perhaps apply a little 5 minute epoxy or even spray varnish over ends of tape so they dont fray or separate?

old jim

rotus623

Thanks Jim, glad to hear it! Not much amperage at all, just enough to keep the old 12v battery up and charged. I didn't spend a whole lot of time on her, but I did try and wrap it as tight as I could. I will pull the flywheel after a few hard runs and make sure stator isnt getting hot in any spots. Worse case scenario is I burn something up and re-wrap her ay? But I will check for shorts, check my resistance, and let you know in about a week or so what type of current I am getting back at my battery when I get the motor back up and running. Thanks again for all of your experienced advice.

rotus623

Okay Jim, ran the motor today for the first time in over a month. She ran great. I checked the voltage at the battery, and it read 12v. Started the motor up, and at idle it read 12.8v, and at about 1500 RPMs it read 13.5v. So I am good to go!! The stator should charge just fine. Thanks again for all of your help. :)

jim hardy

Very heartening news ! She's charging indeed .

Thank you for the feedback, i enjoyed your success from clear over here in Arkansas .

What part of the world are you in?

old jim

dlgoff

Here in Kansas too.

Thanks for the update rotus623.

rotus623

I am in good Ole' Virginia. I always like to get back with the end results to the people that help me out!

jim hardy

i woke up thinking about your motor.

Your first couple of pictures look like a stator that's been fried by a failed rectifier-regulator module.
When the internal diodes short out it lets the battery discharge through the alternator windings and fries them. After battery runs down they cool off.

I am guilty of ASSUMING you checked for that.
If not, here's what i would do:

Remove positive battery wire .
Connect a 12v lightbulb between the wire and battery post . If it lights current is going someplace.
If so, disconnect the alternator winding (unplug plug or lift wires) . If that extinguishes light , current is making its way backward thru regulator and it'll likely fry again.
If it's dark you can just look for small spark at terminal.

Seems obsessive-compulsive i know, and i do suffer from that, but it's such an easy check with such potentially significant result.. I use the $2 test probe from walmart, looks like an illuminated ice pick with wire attached.
You probably did it already. as i said i'm ocd.

Thanks again for sharing your success.

old jim -- "I love the smell of 2-stroke oil in the morning"

rotus623

Amen!!! Well actually Jim I think the previous owner was fishing for the issue, because when I first got the motor, the only thing that was new on her was the rectifier. I assume it went bad, fried the alternator, and in an effort to get the motor running, the rect was swapped out. Thanks for the insight. I am ocd with this stuff also. ESPECIALLY when it comes to safety/reliability when out on the road or water. My life revolves around tinkering with my cars and boats. :) When I get the chance I will check the rectifier just to be sure and post back. Im also going to pull the flywheel after a long day out on the water.

rotus623

Oh and I did notice (before I changed the stator) when I was tuning the carbs, and my screwdriver touched the frame and the carb the screwdriver would spark. Not sure what that would indicate.

jim hardy

I'll GUESS your screwdriver was not far below the stator and the shorted turns distorted the magnetic flux , some of it coupling your screwdriver as the magnet went by.
In a short circuit condition you have large mmf's opposing each other.

1967 was probably before the manufacturers figured out how to make those voltage regulators withstand a brief connection of the battery in wrong direction.
As you know that's easy to do.
Some of them are not regulators but just rectifiers and can be replaced with a simple bridge rectifier for a few bucks. When there's only a few amps available one can just let a large battery absorb them.

rotus623

Gotcha. I tried the screwdriver thing again this morning, and no sparks. I would suggest that you are correct. Good to know that I am not sparking in any areas. The carbs in these guys were known for being a bit leaky, regardless of needle inlet height. Spark + leaky gas + out on the water = a paranoid boat operator.

jim hardy

i've hung out over the stern in Gulfstream changing sparkplugs myself...