possible magnito problem

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Eck
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possible magnito problem

Post by Eck » Mon Oct 28, 2019 8:39 pm

I was riding along fine in my 26 and all of a sudden it started to sputter and lost some power. I switched it to battery and it runs fine. Today I checked the plug and it was clean, no lint and looked in the socket and contact was fine. Disconnected the lead and connected a voltmeter with the black lead grounded to the truck. It appears if I did everything correctly I was only getting about 2 volts when running on battery and did not pick up a lot when given throttle. I think the book says I need around 7 volts to run well. I guess I have a big problem. As a newbe and never torn into this area, any suggestions ?

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Re: possible magnito problem

Post by Steve Jelf » Mon Oct 28, 2019 9:02 pm

When you're running on battery that means the coils are being fired by the battery. They're getting no current from the mag, so the magneto output is irrelevant. When you switch to mag, the coils are being fired by the magneto, and the mag output matters. Where are you measuring mag output? If you're measuring at the post and only getting two volts, then you have a mag problem. If you're measuring at the coil box, the problem could be in the mag or in the switch.
The inevitable often happens.
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Eck
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Re: possible magnito problem

Post by Eck » Mon Oct 28, 2019 9:13 pm

I measured at the post with the connection not attached. Wanted to see if mag and not switch or wiring. Thanks for the reply.


Norman Kling
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Re: possible magnito problem

Post by Norman Kling » Mon Oct 28, 2019 9:16 pm

I had this happen on one of my T's. It turned out to be a problem with the switch.
Norm


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Re: possible magnito problem

Post by Piewagon » Mon Oct 28, 2019 10:34 pm

Please don't be offended by this question. Are you measuring AC volts at the mag post to ground or DC Volts?


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Re: possible magnito problem

Post by Eck » Mon Oct 28, 2019 10:39 pm

AC will use a fluke meter tomorrow and try again used a cheap HF meter today. Never hurts to ask a question I have brain hick ups daily Thanks for the reply learning as I go.


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Re: possible magnito problem

Post by noelchico » Mon Oct 28, 2019 10:49 pm

I had a switch on my 26 partially short out the magneto to where it ran but not well. Several days later, the switch completed the destruction of the magneto. On checking the switch I found a burned out portion visible from the back. I did an in the car recharge and sent the switch to Ben Martin, who did a remarkable rebuild of it. I hope your problem is as simple as mine was. They can be frustrating.


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Re: possible magnito problem

Post by Scott_Conger » Mon Oct 28, 2019 11:10 pm

When measuring Mag voltage, put away the nice digital meter and use an analogue meter. You may be surprised.
Scott Conger

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Re: possible magnito problem

Post by Eck » Mon Oct 28, 2019 11:28 pm

Thank you have one will try tomorrow. Hope get better results Thanks

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Re: possible magnito problem

Post by AndreFordT » Tue Oct 29, 2019 3:33 am

William,
for testing the magneto you need the tester https://www.modeltford.com/item/MAG-SLMT.aspx or you can do this with a analog meter and a testlight with a 12V 21W bulb.

With the tester just connect the tester between the magneto post and the frame of the car and make the engine run. The tester will tell you if the magneto is working well.

With the analog meter and the testlight.
Connect the testlight between the magneto post and the frame. With the analog meter you should test the tension drop over the testlight. To do this just connect the meter the same way as your testlight.
Start the engine and run it on battery. At idle you should read about 7V, a brisk idle will give you 12 to 15V. As the engine speed go up the tension will go up and at about 30V the bulb will blow out. No you know your magneto is working well.

Good luck
Andre


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Re: possible magnito problem

Post by R.V.Anderson » Tue Oct 29, 2019 9:08 am

When a mag develops trouble "all of a sudden," that is, with no warning and no sputtering and/or running rough, but just dies, and then upon checking it the voltage is there but quite low, usually it's something like a bit of wire or a broken cotter pin shorting it. Most often the offender is found at the post but sometimes it's lower down in the field coil where you can't see it. This happened to me twice: when I first started the rebuilt engines on my '14 and my '23; they both ran beautifully for several minutes and then the mags quit. On the '14, I was only getting 2 volts at speed, just like you are. I ran all the checks and determined that the trouble was lower down, so I disgustedly pulled the engine and split it. Sure enough, a broken cotter pin was inserted into one of the windings at about the 7 o'clock position. I soon found that it had come from one of the clutch fingers. I pulled out the broken piece and carefully examined the field coil. It looked OK except for the tiny hole, and it checked out fine electrically, so I cleaned the area carefully (I could do that successfully because both the field coil and the oil were new and clean) and dabbed on a bit of Glyptal, in and over the hole, then cured it under a heat lamp. I was then good to go except for the fun and thrill of re-assembling and re-installing what had been a carefully set up power plant. :x

On the '23, I got no voltage at all; the trouble was a bit of wire at the post which completely shorted the whole works. 10 minutes' work and that was fixed. :D

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Re: possible magnito problem

Post by AndreFordT » Tue Oct 29, 2019 10:14 am

Here a few pictures of what can possibly go wrong with the magneto.
First is a double oval freshly rebuild and run for a few hours.
Attachments
The rebuild coil loop
The rebuild coil loop
Rebuild coil.
Rebuild coil.
Disassembled coil.
Disassembled coil.
The reason why there was fire was the debrit of oil, band material and small metal parts that made contact wih the frame.
The reason why there was fire was the debrit of oil, band material and small metal parts that made contact wih the frame.
Testing the coil loop, one of the coils get fire..
Testing the coil loop, one of the coils get fire..

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AndreFordT
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Re: possible magnito problem

Post by AndreFordT » Tue Oct 29, 2019 10:25 am

Second one was during the recharge of the magnets during the rebuild of an engine.

The magneto loop was looking fine and I tried to use it again. During the recharge of the magnets I set the loop over the flywheel and flashed it three times with 42Vdc. it started smoking at the second time. Needed a total rebuild.

Andre
Belgium

I just need to learn how to put the photos in the right order. The last photo is for the message I wrote just before this one.
Attachments
Finished single loop.
Finished single loop.
What was wrong.
What was wrong.
Smoking loop.
Smoking loop.
Finished double oval loop.
Finished double oval loop.


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Eck
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Re: possible magnito problem

Post by Eck » Tue Oct 29, 2019 1:47 pm

Will do the light bulb / analog meter test next. If that fails think will pull the hogshead for a look see. Maybe could spot some problem. Thanks for the reply Eck


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Re: possible magnito problem

Post by Eck » Tue Oct 29, 2019 2:41 pm

Made the test rig with the 1156 bulb and analog meter. disconnected the connection from the plug and fired the truck up on battery. The bulb got so bright it was hard to read the meter. Looks like my problem lies in the wiring or switch going to the coils. Eck


R.V.Anderson
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Re: possible magnito problem

Post by R.V.Anderson » Tue Oct 29, 2019 3:41 pm

That's good news; it will save you a lot of work!


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Re: possible magnito problem

Post by Eck » Tue Oct 29, 2019 5:14 pm

Voltage seems a little low goes from around 5 volts at idle to about 25 at higher speeds but unsure how good my meter is. But at least it is putting out according to the bulb brightness. whew


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Re: possible magnito problem

Post by Scott_Conger » Tue Oct 29, 2019 5:45 pm

Have a look at this:
http://www.mtfca.com/discus/messages/70 ... 760271.pdf It is a very good procedure with some basic values to look for...this is what most have used to determine health. This is what you just did, but gives some values for you.

And then know that an accurate picture of your Mag's health can only be had by using something along the line of a St. Louis Electrical Works magneto meter (original or repop) or Electronically Cranked Coil Tester (ECCT). If you ever come across either device for a good price, grab it. It's always good to have proper diagnostic equipment available.

These devices apply the proper load and give an RMS reading so that you don't have to guess about RPM vs voltage, etc.

An accessory Magnetometer is a handy device to have in the car, but it is NOT a diagnostic tool as it only gives a spot-check value with no RPM data...an on-board view of what's happening at that very instant, with no other information.

Your values don't appear to be too awful, or likely the source of the sputtering, as you are probably now concluding yourself.
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!


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Re: possible magnito problem

Post by Eck » Tue Oct 29, 2019 7:24 pm

Tomorrow I will take out , clean contacts and re seat my coils. while out will check my wire to the timer. My next area and thought how to test my ignition switch. Mine is a 20 some year old re pop but only has been used last 3 years since got the truck going. Will test wires for grounds as disconnect one by one. If the switch is the problem, I will send it off to get a good re build. Thanks for the help

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Re: possible magnito problem

Post by Fordwright » Tue Oct 29, 2019 8:59 pm

It might be overkill, but it's fairly easy to measure the output with an oscilloscope.
That might be able to show you that one of the pickup coils is bad, or how much voltage is being generated at various speeds.


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Re: possible magnito problem

Post by Eck » Wed Oct 30, 2019 4:37 pm

I rigged up a two way switch And by passed the ignition switch . Still will not run well on mag so in spite of what looked like a good mag I guess I was wrong. Have to give up for a while as problem is burning me out. Eck


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Re: possible magnito problem

Post by Scott_Conger » Wed Oct 30, 2019 4:55 pm

I can understand your feelings.

Let me leave you with this, though. While a little low, your mag output at 25V at speed is still FAR in excess of anything your battery puts out. It is hard for me to believe that the mag is the root cause of your sudden loss of performance on MAG setting. Your not knowing it's performance prior to your present troubles make it a potential ideal red herring.

When you have the desire, I suggest this:

1. put out a request for a kindly member to loan you a St. Louis tester. That will confirm or refute a magneto problem then and there. Period. End of story. Then you can decide to fix it (or not) or it will force you to look somewhere else.

2. send your coils to a reputable rebuilder for testing and rebuilding as necessary. Regardless of what your present trouble is, rebuilt coils will pay you back in spades over the coming years, and a bad set of coils which are adjusted to run at a specific voltage can run terribly on mag. A properly rebuilt and adjusted set of coils will not care what their voltage or source of voltage is.

3. clean your timer and consider a new loom to the timer. Oil soaked wires or with high resistance shorts can be more pronounced with higher voltage.

Best of luck for a quick fix after you recouperate.
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!


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Eck
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Re: possible magnito problem

Post by Eck » Wed Oct 30, 2019 6:02 pm

Got my coils re built two years ago . Took out coils today for a look see. Cleaned the timer first thing and re greased the flapper. Will check the wiring going to the timer. If there is a problem with the coils or timer, why does the car run well on battery. When I hooked up the two way switch, I bypassed all except the mag and coils to timer. Thanks for your help. Eck


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Re: possible magnito problem

Post by Scott_Conger » Wed Oct 30, 2019 6:27 pm

If there is a problem with the coils or timer, why does the car run well on battery.
I am not saying you have a coil problem, but to answer your question, the method used, and the knowledge of the adjuster and the equipment used to adjust all have a bearing on coil performance. Coils can definitely be adjusted to run better on battery than mag. Again, not saying this is your case, but trying to answer the question you asked.

Regardless of what this turns out to be, the values you have stated that your mag puts out, indicate plenty of voltage to run the car well. Perhaps, not like new, but enough. That said, mag posts DO go bad, and CAN go intermittent. Additionally, the lead "button" on the top of the mag ring can become dented from constant pressure/vibration or otherwise deformed and depending on the design and health of the post, will have more or less pressure at the contact point.

I really stess the value of a St. Louis tester to simply confirm or eliminate the mag ring and mag post from your list of potential root causes. You are now at the stage of process of elimination, since the cure didn't come quickly. Find and use a tester.
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!


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Eck
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Re: possible magnito problem

Post by Eck » Wed Oct 30, 2019 7:16 pm

The coil doctor did my coils . I took the mag post apart to see how it loose as I have the type that screws in and has an oil connection on the side , and can not find a replacement without buying the whole oiler kit. The post is insulated from the housing and has a fiber washer on a shoulder to adjust its depth into the mag contact. May see if I can get another washer to add to put the contact point further into the contact button. You are correct I will look for a tester or brake down and purchase one . Thanks again for the help as just talking thru problem sure helps clear a path. I would not think trash in carb due to runs well on battery. Any thoughts. My drain HH and pull bowl down to look for anything. Had tank cleaned and coated after sitting for 30 years. Eck


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Re: possible magnito problem

Post by Eck » Thu Oct 31, 2019 7:24 pm

Today decided to test the timer and wire from coils to timer. I wanted to make sure there were no coils activated so hooked up battery and activated. Noted # 4 coil was firing. Turned crank to find an off spot and found there was not one. Took off timer and found #4 coil was activated continuously. Found the contact was grounded to the timer case. Ordered a new timer and will investigate present timer when removed. Still do not understand why it ran better on battery maybe more amperage ? Crossing fingers and thanks for your help.


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Re: possible magnito problem

Post by Scott_Conger » Thu Oct 31, 2019 7:40 pm

Sounds like you're on to it...good luck
Scott Conger

Full Flow Float Valves - deliver fuel like Henry intended!

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