Correct voltage at battery, at idle 16.6?

89 Johnson 150gt

Tach isn't working, was advised if it wasn't that probably isn't charging either due to bad rectifier. Have ordered and received CDI replacement regulater/rectifier. Bench tested and compared and seem to be the same. Previous owner said tach will work after running a while? So, I've ohmed out the wiring from the tach to terminal block on motor, all good. Today I've voltage tested the battery before start 12.45, after start 15.9, after a few minutes 16.6 at idle, 17.45 at higher rpm. This value seems high to me and don't want to fry new battery. Should I replace the regulator/rectifier? If so my next question is advice on pulling the flywheel as I attempted on Sunday with puller and correct bolts threaded with impact, Didn't budge! I did apply a penetrating oil, small amount, but will I need to heat it?

This forum has been great!

Eric

Re: Correct voltage at battery, at idle 16.6?

It sounds as though you have a unregulated rectifier. Does it look like a cylinder atop a triangle or is it mounted in the engine under the flywheel?

The voltage is fairly normal for an unregulated rectifier; they look similar to the one shown here:

Re: Correct voltage at battery, at idle 16.6?

35 amp water cooled under flywheel. Sounds like I'm going to have to change it out. If the voltage is unregulated will that cause the tach not to work, or do I have a bad tach as well? Too much voltage will cook a battery, but would it take out a tach?

Re: Correct voltage at battery, at idle 16.6?

Here's how you test it. http://forums.iboats.com/showthread.php?t=190636

Re: Correct voltage at battery, at idle 16.6?

Yes, that voltage seems awful high...I agree...Bad Rectifier will boost voltage to dangerous level....As far as getting flywheel off..I would try something else before going to heat...I would be really careful with heating it.

Re: Correct voltage at battery, at idle 16.6?

Forgot about your tach... the voltage could contribute your tach problem..but unlikely.....I think you had a tach problem obviously before you had this problem...I think it is bad and should be replaced.

Re: Correct voltage at battery, at idle 16.6?

OK, any advice on removing the flywheel?

Re: Correct voltage at battery, at idle 16.6?

The flywheel is torqued to 150 lbs. You may need a special socket to get down into the flywheel to loosen the nut. A normal automotive flywheel puller should work. Once you get the puller stretched tight, rap the end of the shaft with a hammer. Should pop right off. An engine like yours with a regulated rectifier should be in the 13.5 volt range. I've seen these XP/GT 35 amp rectifer/regulators catch on fire in the past. While the damage is usually limited to the regulator, the fire can damage the flywheel or paint on the cowling. I think you are right in addressing this problem now.

Re: Correct voltage at battery, at idle 16.6?

I had to heat my flywheel to get it off. I didn't use a torch. I used a heat gun to avoid the damage a torch can cause. It doesn't need to get all that hot. Just heat to the point where you can't leave your hand on it for long. You just need that flywheel metal to expand a little bit and POP, off she comes. Don't forget to leave the nut on the crankshaft a few turns. When that flywheel does let go the nut will keep it from jumping off the motor and damaging itself or you.

Re: Correct voltage at battery, at idle 16.6?

Thanks for the advice about the flywheel. I was ready to take it to dealer, but have changed my mind. I was a little leary about heating it or raping it with a hammer. I will attempt it again.

Eric

Re: Correct voltage at battery, at idle 16.6?

Done! Took three raps with hammer. Job is complete, tested voltage output 13.? (forgot that number already). Tach is operating! Thanks to all that posted. I consider this forum a very valuable tool in my tool box.

Eric Sizemore