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Murray 46103X92A
Briggs 42A707-2653 E1 (Opposed twin)

I had to replace the coil on this one. Afterwards, I got spark and it started right up. I can't say if I checked the charging system or not. But finally got it ready to mow, and other than having to choke it off and on, it seem to run ok. I put the meter on the battery, while it was running, and the numbers were changing so fast, I couldn't get an accurate reading. None the less, I wanted to check out how the carb ran and the new spindles & blades performed, so like a dummy, I mowed with it for about 30 minutes.
After letting it sit for about 30 minutes, I tried to start it, and was getting no spark. So I parked it for the night.

This morning, I'm getting fire. But after mowing with it a little more, I put the meter on it, and once again, the numbers are moving so fast, I can't get an accurate reading.
One thing I did notice, that I'm also getting voltage on the negative side of the battery. It's jumping around like it is when I've just got the leads to the battery.

Oh, and yesterday I noticed some fresh oil on top of the starter and down the side of the engine.

I found the oil leak. The plate the holds the back cover on, was missing the bolt closest to the starter. I found another bolt for it. I hope that stops the leak. I doubt it will. But maybe.

Still trying to figure out why the meter is jumping like it is. The alternator was tight.

You should be checking the regulator.

I don't think this has one. Where would it be?

Then you have a dual circuit with a diode with you have lights on it.

Yes it's just the two alr. wires with diode.

Did I mention I'm getting power to the ground side of battery?

Alternators generate AC electricity, which is why they are called ALTER-nators and not generators.
A diode is a one way valve for electricity so only the + section of the alternation goes to the battery.
IF the diode goes bad the wire to the battery will go from +13V to - 13 Volts and thus give you strange readings.
Pumping AC into a battery will destroy it in no time flat and of course as you recharge it then discharge it the recharge it then discharge it, it will never end up with a net charge, just get hot.
You can confirm this by poking a pin through the red wire an inch or so away from the diode ( alternator side ) and probing the red wire from the mower side of the plug ( plug disconneected ).
If it is good you will get continuity with the meter one way and no continuity when you swap the meter leads.
Yours will most likely read continuity in both directions.

Thanks Bert. I'll check that out.

Here's the meter reading I get from the battery posts and the wires from from the alternator.
https://www.youtube.com/watch?v=24HuUJiUbwE

Also, I put a test light on the two wires from from the Alt., and it lights up on both wires. One side lights up much brighter than the other.

UPDATE: Bert, I did the test like you said, and didn't get continuity from either way, when touching just the pin and the connection. But, with the pin through the red wire, about an inch back from the diode, I did get continuity when I touched the other lead. Even when I switched them.

BTW, I get juice to the negative side of the battery, ONLY when the engine is running.

With that said, it can only be the stater or diode, right?

Any help you guys could give me, would be great. Could this be a bad alternator? A hot wire grounding out?

Take off one lead from the diode and check again for continuity one way only.

PTmowerMech said:

Thanks Bert. I'll check that out.

Here's the meter reading I get from the battery posts and the wires from from the alternator.
https://www.youtube.com/watch?v=24HuUJiUbwE

Also, I put a test light on the two wires from from the Alt., and it lights up on both wires. One side lights up much brighter than the other.

UPDATE: Bert, I did the test like you said, and didn't get continuity from either way, when touching just the pin and the connection. But, with the pin through the red wire, about an inch back from the diode, I did get continuity when I touched the other lead. Even when I switched them.

BTW, I get juice to the negative side of the battery, ONLY when the engine is running.

With that said, it can only be the stater or diode, right?

Click to expand...

No continuity between the pin and the plug in either direction says the diode is open circuit.
This should mean you get no juice back to the battery at all..
In any case, the diode is stuffed.
You can solder in a new one or replace the whole stator.
Soldering is a messy job because Briggs soldered it to the pin in the plug.
So you need GM pin tool to remove the red wire from the plug then desolder the diode at both ends and solder in a new one then refit the pin into the plug.
Works about 25% of the time.
Usually I end up cutting off both plugs and fitting new T shaped 2 pin spade plugs with the diode soldered in a fair way back up the wire.

In all honesty a new stator complete with a real full wave rectifier is a much better way to go even if it is a lot more expensive.

EngineMan said:

Take off one lead from the diode and check again for continuity one way only.

Click to expand...

Thank you, everyone. I didn't want to replace the stator, unless I just had to. I don't like replacing good parts. BTW, Bert, what came to mind when you seen the way the meter was acting.

It even did the same thing, when I grounded the meter to the engine, then touched the negative side of the battery.

I never looked at it, there is no point .
When you know what the system is , how it should work and how to test it, faaffing around with the unknown or unnecessary just confuses things.
PArticularly with high speed , ranging multimeters that will skip around from AC to DC to micro volts to volts faster than you can read the screen.

bertsmobile1 said:

I never looked at it, there is no point .
When you know what the system is , how it should work and how to test it, faaffing around with the unknown or unnecessary just confuses things.
PArticularly with high speed , ranging multimeters that will skip around from AC to DC to micro volts to volts faster than you can read the screen.

Click to expand...

The video is maybe 30 seconds long. Well worth the watch.

Hey,
I do this stuff every day for a living.
I know what a bad diode looks like when you put a meter on a running alternator.
It is your engine so you might find it facinating.
The meter would have been swinging from + 14 V to - 14 V or there abouts, every time a magnet passes a coil .
There are 36 magnets ( from memory) on the flywheel and 24 coils on the stator wired in pairs to give you 12 sets.
So you are going to get 18 x 12 x 3,600 pulses per minute down the wire.
The meter can not read that fast to do that you need an ossilliscope so it throws up random numbers.
Cheaper DVM's might even add the pulses together so you might get 28 V or higher readings.

AS mentioned previously, waste of time looking at it as it tells you absolutely nothing apart from the fact that the diode is bad, and then you still have to confirm that with a continuity test.

I replace the stator, and getting the same reading off the battery. Still getting juice to the negative side of the battery. Still getting everything I mentioned.
Even after replacing the stator and solenoid, cleaning the connections. Chasing wires, replacing the ground wire. Adding a ground to the new 4 prong solenoid.


But it runs great. Only thing is, after running it for a little while, if you kill it, it won't start up for about 10 minutes. (No fuel solenoid)

So it looks like you are still getting an AC feed to the battery.
First pull the stator plug and measure the voltage between each pin to ground.
Do it in both DC and AC mode
The red wire should read + 12 to 15 V DC
The black wire should read 12 to 20 V AC.
The black wire only powers the lights but it looks like it might be feeding back into the charging system.
Check the battery also in DC & AC modes.
If you can do it , confirm that the black wire is back feeding by removing the pin from the plug or cutting the wire.

Is this your mower, have you owed it since new.
I ask this because a shaved monkey that learned how to work a video camera posted on U tube that you can join the two alternator wires together and "free extra electricity".
And because every one always wants something for nothing way too many did just that.
Has the ignition switch been changed ?
They are different for AC lighting where the switch makes a ground connection than for DC lighting where the switch connects the lights to the battery or DC feed from the alternator.