Magneto

[Bill67]

Hello. I’m new to all this and this is my first post. I’ve owned a 1925 touring (1919 engine) since 2000, but just recently got it in running condition. It was built in the mid 1980s by someone else. It will not run on magneto at all. How does the magneto post and pin work? I’m not sure if the problem is with the magneto or if the problem is in the post or somewhere else.

Some of the previous posts on diagnosing problems with the magneto have kind of gone over my head.

Thank you for any advice.

[Norman Kling]

The first T I bought, the seller showed me that the car would run on both battery and magneto. I later found out that both sides of the switch were connected to battery. The magneto didn't work!
Norm

[Moxie26]

Hi Bill... I think it'd be easier to check the roster for a local chapter near you and hopefully someone in that chapter can be of help with your magneto question first hand. Good possibility that all is needed is a magneto recharge.

[Kerry]

First, remove the post and see if it has a magneto, should see a lead pad for the prong of the post to sit on.

[Bill67]

I tried to attach photos but failed. Yes, there is a little lead pad.

[TRDxB2]

There are several reasons why MAG doesn't work
1. no magneto
2. demagnetized magnets
3. Dirty/faulty MAG post
4. Faulty ignition switch. I just repaired two that had intermittent contact when switched to MAG causing back fires

You didn't say if you checked the wiring to see if the ignition switch MAG Contact has continuity with the COIL contact when switched on MAG
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[John kuehn]

Could be several things not causing a working Magneto. Hopefully the magnets just need a recharge. As Norm said over time and different owners not knowing anything about a T electrical system may be the issue. Being wired together in the switch is what happened in Norms case.
And if the magneto ring has a broken winding that would mean pulling the engine to start with.
Find a local T club that knows how to charge the magnets in the car correctly if it’s determined that’s what it needs. The MTFCA T electrical system manual is good to have also. Those publications are available through tha T parts houses.

First thing though is to get the Ford service manual to acquaint yourself to a T engine and chassis. BE SURE YOU FIND OUT ABOUT WHAT NOT TO DO before try to repair your magneto and how it’s wired in the car.

Here’s an earlier post about how to recharge the magneto in the car. BUT as the earlier post indicated make sure to check the switch contacts and wiring befor you attempt to charge the magnets. It could be just a dirty switch contact. http://www.mtfca.com/discus/messages/17 ... 1299531922

[speedytinc]

Disconnect the wire from the post. With the motor running, check the voltage @ the post with an analog volt meter. It should put out 20+ volts @ higher speeds. If you get nothing, it could be a wiring/switch problem, a bad field coil or demagnetized magnets. Check continuity with the motor off. Should be some, if not, an open field coil. If you have continuity & no or weak voltage, THEN try an in car magnet recharge.

[Bill67]

Thank you to all who have responded. I’ll try some of these ideas.

[Norman Kling]

Another problem I had with the first T was, it needed a new starter ring. So I pulled everything and then went to a swap meet and found an engine completely rebuilt including the transmission, so I bought it and installed in my T. The magneto worked the first time I took it out and went about a mile and suddenly it stopped. After that I ran on battery for about 10 years. I had rewound 3 magneto coil rings so I thought I would install one on that car so pulled everything out and found the funnel for the inside oil line laying in the bottom of the crankcase! When it had come off it cut the windings on the magneto ring and that is why it quit working on magneto! I also had a magneto plug oil line on that car and between that outside oil line and the inside line without the funnel, it got enough oil that it ran for 10 years including the Canyonlands tour in Utah, with no engine damage. I installed another inside oil line and one of the magneto rings I had rewound, and it still works today which is about 20 years later. So you see, many things could cause a problem with the magneto!
Norm

[jiminbartow]

On top of the magneto coil inside the transmission is a button of solder. The magneto post has a sharp contact that, when the magneto post is screwed in, embeds itself into this button of solder. Sometimes the sharp contact pops off of the button and needs to be positioned back on the button of solder. Before doing so, it will help to sharpen the contact so it will better embed itself. Once, after crossing a rough railroad track, my engine suddenly died. I immediately switch it from MAG to BATT and the engine continued running. When I got it home, I found that the post had come off the button as I described.

Do you have an outside oiler connected to the magneto post? If so, it is possible that the connector that is screwed into the side of the post could be screwed in too much and is shorting out the post. If this is the problem, you can grind off the connector so that it can be tightened all the way without touching the post, or do like I did and insert a spacer.

The possibility exists that the coils need to be rebuilt. In that case, the engine will have to be dismantled and the mag coil ring removed and sent off to be rebuilt. A very arduous task. If the coils are good, the magnets may need to be recharged. I recharged mine in 2010 the last time I rebuilt my engine which was out of the car and they are still as strong as ever. I have a very good process that worked for me but the hogshead must be removed to determine the N & S magnets and this is most easily done with the engine out of the car, not because the hogshead can’t be removed while in the car, but because of all of the gaskets that need to be installed in place, while lining up the holes, the installation of the 3 transmission bands, the weight of the hogshead and the confined space in the cab in which you must work, it is almost impossible to properly install the hogshead while still in the car.

I just attached a picture of the cross-section showing the solder button and how the sharp magneto post embeds itself into the button. There are several different types of magneto posts, but they all work the same way. Jim Patrick

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[John Codman]

I'm pretty much repeating what was said earlier, but to keep it simple: Disconnect the wire from the magneto coil and check the voltage with the engine running. There's no reason why you can't use a digital meter, but be sure that it's set on AC. As was said earlier you should get at least 20 V with the engine running at a speed well above idle. If you do not, the issue is with the magneto; if you do, the problem is somewhere else.

[jiminbartow]

John. Since Bill is new to Model T’s, what lever settings would you recommend to achieve “well above idle”, in order to attain 20 volts for the magneto test? Jim Patrick

[Bill67]

Thanks for all the help. A buddy came over tonight and we tried some of the suggestions. We determined the problem was in the switch. We took it apart and bent some contacts. I put it back together, started it on battery, switched to magneto and it ran. I was amazed.
Thanks again.
Bill