Magneto question

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Model T Ford Forum: Forum 2008: Magneto question
Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave K. on Monday, January 19, 2009 - 12:17 pm:

Yesterday I took my 26 Dump truck for a drive. Everything seemed to be running fine on the mag. Then it just died. Before the engine stopped I switched it to the battery and it ran fine. When I switched it back to the mag. it died again. I did not have a chance to check anything out on it last night. But was curious if anyone had any ideas on what the problem might be?

Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino on Monday, January 19, 2009 - 12:21 pm:

My truck has a tempermental ignition switch. If I jiggle it a little it works fine. If that's not it, look for a loose connection in the mag wiring curcuit, the switch, etc.

That's what I'd do first, particularly since it was running fine then just quit.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hap Tucker on Monday, January 19, 2009 - 12:26 pm:

Dave,

It could be lots of things. Several common causes are:

The ignition switch is not making good contact (clean the switch contact or in some cases just turn the switch back and forth and that will clean the contacts enough).

Lint collected on the mag post and is causing the problem. Remove the mag post and clean the lint out.

Loose connection / wire -- check all the connections between the mag post and the switch and coil box.

See also the last page of: http://mtfca.com/books/1926Inst.htm for additional ideas.

Normally if it was running good and then stops running good on Mag but still runs on battery and there were no loud noises -- it is usually something minor to fix.

Respectfully submitted,

Hap Tucker 1915 Model T Ford touring cut off and made into a pickup truck and 1907 Model S Runabout. Sumter SC.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Cascisa in Poulsbo, WA on Monday, January 19, 2009 - 12:27 pm:

Dave,

Try these things :

1. Remove the Mag Post - clean it - Reinstall it - make sure it makes good contact with the mag ring

2. Measure the output of the mag with an analog type meter (AC volts). There is a proceedure to measure it under load with a light bulb posted on this forum many times.

3. Check the wiring from the mag to the ignition switch.

4. Check the ignition switch itself for proper operation.

5. If no luck by now you are looking at an engine teardown.

Best of luck.

Be_Zero_Be


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Cascisa in Poulsbo, WA on Monday, January 19, 2009 - 12:28 pm:

WOW - A lot of guys typeing at the same time !!! :-)


Be_Zero_Be


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, January 19, 2009 - 12:32 pm:

You have a bad connection somewhere. Either an open or a ground in the magneto system. when you run on battery, check for output from the magneto terminal on top of the hogs head. Use an analog AC voltmeter. If you get nothing, the trouble is inside. It could be a bad connection from the magneto plug to the magneto. Sometimes band material causes this. If that is not the trouble, use an ohm meter to check (with the engine not running) The magneto contact inside the hogs head to ground. You should get very low resistance. If you find an open here, you have a problem with the magneto coils.

Going back to the check with the AC voltmeter, if you get AC current at the magneto terminal, the magneto is working, and you might have an open in the wire from the terminal to the terminal block or at the ignition switch.

Other causes could be low output of the magneto, but that doesn't usually come on suddenly. It would usually cause poor idling, but runs at a higher Rpm. Could misfire when running.

If you find that the magneto itself is not working, and it is not caused by a bad connection between the contact and the post. It is a good idea to investigate to see what caused it. It could be caused by something which cut the magneto coils and that could be a loose keeper on the magnets. You would at least need to remove the hogs head to find a problem like this.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave K. on Monday, January 19, 2009 - 12:43 pm:

Thank you for all the advice. I will check all of these things out when I get home from work. (This will make for a long day on the job,thats for sure.) If it turns out to be a major tear down, I may be asking alot more questions.

Thanks again for all of your help.

Dave


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