V4 flywheel help

bishopcherrycoke

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Mar 11, 2011
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Hello all. I have a 1978 85 hp Erude. My question is, is the fly wheel suppost to have magnets on it? I have hunted down diagnosises as to why my charging system isn't working until i just accepted te fact i have to throw the batteries on a charger every other day or so. I just recently saw a picture of an outboards fly wheel and it has magnets. Once I thought about it, I am thinking how dumb I am because how else would the flywheel create electricity??? But maybe there is something I am missing...

So far I have replaced...
Stator, rectifier, aand... One other part that's slipping my mind... Maybe i just need a new flywheel??? Mine does does not have anything on the inside of it. Just bare metal. Or aluminum.. Can somebody answer this silly question for me please...
 

gm280

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Jun 26, 2011
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14,585
Re: V4 flywheel help

For starters, what model is your 1978 85 HP Evinrude. The IPB (Illustrated Parts Breakdown) I've just looked at shows three different model numbers for an 1978 85 HP Evinrude and all three have rectifiers meaning they have some type of AC generating capacity. Those model numbers are 85890C, 85895C and 85899C). Which one is yours? However, the output of your engine may not simple be enough to charge your battery from just a short run. And that may be why you have to charge your battery every few days. You can easily check the voltage coming out of your rectifier pack using a VOM (Volt Ohm Meter) meter. Did you actually see the underside of your engine's flywheel to verify there are no magnets installed in the aluminum? My 1976 Johnson 40 HP has them machined into the flywheel itself and to a casual observer it would look like there are none. Post some pictures for us...
 

emdsapmgr

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Re: V4 flywheel help

Your factory-installed flywheel, along with most of that era, should have magnets. They are cast into the inside outer lip of it. (Don't confuse it with some later ones that have magnets glued in.) If you look closely, you will see variations of texture in a regular pattern inside the inner lip of the flywheel. Those are the magnets. The magnets work to create voltage to run the ignition and re-charge the batteries. It's rare for your type of flywheel to lose it's magnetism and quit working. Even the very earliest of crossflow engines had charging systems. Keep in mind that the stator has two types of charge coils. Most of them provide voltage for the ignition. A couple of them provide voltage to recharge the battery. I suppose it is possible that the battery charging coils are bad on both stators, however small that probablility is. I'd be looking at the battery. The only time your engine uses battery power is when it starts. Once started, the engine runs off it's own internal voltage. (except if you have power trim.) In the days when engines did not have charging systems, you could usually go for a few months before you had to recharge the battery on the old V4 engines-since it's only used for 15-20 seconds each time it starts. Have you load-tested the battery?
 

bishopcherrycoke

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Re: V4 flywheel help

I had two brand new (last spring) batteries. I boat alot at night an have the lights and stereo on. I'm also not stingy with the trim.

I put a volt meter on the battery itself and got the typical 12.2 ish volts. When I fired it up, the voltage went up very slightly. I dot remember the number. I did the same with amps. The amps went up very slightly when running. Maybe I am just using too much? In 1978 maybe it wasn't meant for stereos, lights and electric gauges??
 

emdsapmgr

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Re: V4 flywheel help

Your early engine has a rectifier only. A charge battery should read approx 12.5 or 12.6 volts. Yours may read 12.2 volts just after starting. After running it for 20 minutes, the voltmeter should go to 16+ volts. That's normal. Does your boat have a tach-is it acting up at all?
 

daselbee

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Jan 20, 2009
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2,765
Re: V4 flywheel help

Some of the simplest things...:facepalm:
Put a steel screwdriver up to the inside of the flywheel. If it sticks...you got magnets.
But beyond that...you HAVE TO HAVE magnets or you would NEVER generate voltages to power up the ignition system.

Your flywheel has magnets. Whether or not your stator has the coils necessary to charge a battery is a question...but I am sure it does.
Look for problems elsewhere.
 

bishopcherrycoke

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Mar 11, 2011
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Re: V4 flywheel help

My tach does not work. I bought a new tach, checked and rechecked all connections but still have no working tach. I will check if the flywheel is magnetized in the morning. It's still winterized and cold here in Illinois, so I won't be able to run the motor for a few more weeks. Thanks for the tips.
 

emdsapmgr

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Re: V4 flywheel help

The tach gets it's signal from counting pulses from the engine's charging system. The rectifier both charges the battery and sends signals to the tach. Usually when the tach starts to act up, you will find that the battery is not being charged. Since you have replaced both the stator and rectifier, it's probably time to check output voltages. You may find the ignition troubleshooting information helpful at this website: cdielectronics.com You will need a special "peak-reading" voltmeter to perform stator voltaqe output tests on the engine when cranking.
 

gm280

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Re: V4 flywheel help

If you think about it and understand what a rectifier does, there is no reason for any rectifier IF there is no AC output to rectify. I mean why would they put a rectifier on any engine if there was no need to rectify an AC voltage...? So the fact that you have such a rectifier means your engine has the ability to output a voltage to the battery for quote “charging”. Now it may not be a great amount of current, but there still is a DC voltage coming from your engine to the battery. And it is a measurable voltage as well. So if you put a volt meter across your battery and start your engine, you should see a slight increase in voltage telling you the output voltage from your engine IS charging your battery... The reason you have to charge your battery yourself is because you are using more current then your engine is replenishing for the time your engine is running...
 
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