Yep the title says it all, last weekend, we set off for a 120 mile drive, within 10 minutes the mag failed to work, popped, farted and the car came to a stop.
We had been driving the day before without any problems, or even any sign of problems.
It runs fine on battery.
I pulled the coils, checked the contact fingers, all seem ok, there is nothing sitting in the bottom to break the contacts, I've checked the pickup for continuity, it is ok too and sitting on the top of the field ring solder contact point.
Any ideas ??
PS - I pulled the strainer out to have a look and found two pieces of wire, not sure its the type of wire l have used to fasten bolt heads in place ??
My guess.... Something (perhaps the wire) has gotten between the magnets and coils and caused it to short out the mag. Maybe its scratched the insulation off, causing a short..?
Sure the rest of the gang will chime in and help you troubleshoot.
When you say you checked the magneto post for continuity, did you actually remove it to check make sure you don't have a piece of dirt in the way?
Also did you check simple things like your connections on the backside of your switch plate and to the back side of the coil box?
You shared you had already checked the mag post on top of the transmission cover and it was clean and making good contact. That is a common area that gathers lint etc. and will break the connectivity over time [item 6 below].
You also shared that it runs fine on battery so that eliminates most of the reasons listed in the Ford Manual and pasted in below from: http://www.mtfca.com/books/21manual.htm
ENGINE STOPS SUDDENLY
1. Gasoline tank empty.
2. Water in gasoline.
3. Flooded carburetor.
4. Dirt in carburetor or feed pipe.
5. Magneto wire loose at either terminal.
6. Magneto contact point obstructed.
7. Overheated-account lack of oil or water.
8. Gas mixture too lean.
Number 5 above may still need to be checked.
You didnít mention which Model T was giving you problems. If it was the ďimproved carĒ and if you rebuilt the ignition switch some reproduction parts are know to not be of as good a quality as some of the original parts. But the switch (even on the 1913) could be causing the problem.
Finding stray bits of wire in the engine is normally not a good thing. I would recommend looking carefully for other bits of wire and figuring out where the wire came from. I would drain the oil (save it if relatively new)/ Turn the engine over by hand and look through the transmission cover inspection hole, and the drain hole and see if you see any other bits of wire stuck to anything etc. What type of wire is it? Post a photo etc.
After you check the connection at both ends of the Magneto wire if that simple thing doesnít fix it, then I would recommend checking the magneto for out put see John Reganís blub test at: http://www.mtfca.com/discus/messages/179374/183126.html
Good luck, Iím sure you will figure it out and hopefully it will be a minor fix.
Hap l9l5 cut off
If the car runs fine on battery it has to be something directly related to the circuit that relates to the magneto.
To me it sounds like something got under the mag post.
I'm like Dan B. You didn't say if you removed the mag post from the transmission cover and actually looked at it closely and inside the trans cover.
Either that or the mag contact in the switch could have a connection problem.
One source of wire might be wires that locked the wrist pin bolts. They break and drop into the oil sump. Removing the pan lower inspection plate allows you to shine a flashlight up into each bore and see if all 4 safety wires are in place. I also agree you need to prove that the problem is not an "open" between the magneto ring and the bottom strip in the coil box. Checking the mag post for lint is only one step in that process. Move on to the next point along the path that ends at the bottom strip in the coil box. Since the car runs on battery then the wire to the bottom strip is common and you don't need to go inside the box itself in this particular instance.
My car did the same thing last spring. Turned out to be the switch. The new switch back wasn't any better than the defective old one. I dug one out of my pile and problem solved.
I had one on which the magneto stopped working shortly after the engine which had been overhauled was installed in the car. I drove it for about 10 years on battery and then when I was restoring another T, I rewound two magneto coils. I decided to pull the engine on which the magneto was not working and install one of the coils in that car. I found a piece of metal in the bottom of the crankcase. It turned out to be the funnel of the oil line which must have been rubbing on the magnets and when it broke off, the magneto quit working. Fortunately I have an outside oil line and that is all the oil the engine had been getting, that and whatever oil went in through the end of the inside pipe without the funnel. Anyway, I took a few shims out of the bearings and installed the new coil ring and recharged the magnets and now, ten years later it is the best running of my 3 T's. You need to test the output of the magneto directly from the post to see if it is working. Other posts tell how to check it using a light bulb and an AC analog volt meter. If you get a good output from the magneto post, you can concentrate on the wire between the post and the ignition switch and the switch itself. If you don't get at least 6 volts at idle and higher as the speed increases, you can concentrate on the magneto itself. It is important not to accidently connect the battery to the magneto while making your tests.
I have exactly the same problem with my 22 Runabout. Suspect it may be the switch but have not had the time yet to open it. Would be interested to know what caused your problem
Ok thank you, l will remove the trans cover and spin the flywheel and search for more bits of wire.
Mag post dirty was my first thought, nope, it was clean, oil is 1 day old, good idea, drain it and check for more bits.
A job for Saturday.
Hap - 13 runabout.
My wife cooked the engine on the other 13 some hours later on the same run..
Lost two cars in one day, that's gotta be a first.
David - Just wondering,.....the bits of wire you found,.....are they bits of copper wire or otherwise,.....???
I found a very disappointing short circuit in my magneto.
Last year I had the same problem. And I performed all of the above tests & visuals.
A friend and I pulled the engine & removed the hogsheads and block in preparation for a mag rebuild. Were we PO'd when we found a circular piece of aluminum foil type material hidden underneath the solder blob contact point. It was actually hidden from view by shining a flashlight through the threaded hole in the hogshead.
Up until that time I had a habit of poking my index finger through the aluminum foil seal of a quart sized bottle of motor oil when opening. Obviously, one of these seals had come loose from the bottle while pouring and hunted it's way back to a point that could short the system. And it found it's mark.
I now cut the foil with my pocket knife, then remove the circle and dispose it before pouring.
If the wire is steel wire, unfortunately, it will stick to the magnets and spin around with the flywheel. Often when that happens, it will cut into the magneto coils or will destroy the insulation. Even if you later find the wire inside the crankcase, the damage will have already been done.
The small triangle piece that the solder blob sits on ( under the mag post ) what is it in contact with under it - or is it insulated from everything else ?
I had the cover ( hogs head ) off last week for pedal bushing repairs, never missed a beat prior to this problem.
That piece is insulated from everything else but the contact. It has a rivet through it into the frame of the magneto ring. If it is grounded to anything it would knock out the magneto. Your picture shows a 26 or 27 T. If so, the magneto plug is threaded into the hogshead. It is possible that when you replaced the hogshead, it might not be making good contact with the solder on the top. I have found that the magneto plug oilers don't have as much spring tension holding the contact in place. If that's what you have, you might need to do some work on it to make better contact. Even the placement of the hogshead could be part of the problem. If your felt piece is not trimmed at the end, it could cause the hogshead to be higher above the crankcase by a fraction of an inch. Just enough to make the contact poor. If you have the original type plug contact, stretching the spring a little could solve your problem.
I recently helped a fellow who had a failed magneto and here is what we found. Your comment above made me think if this "I had the cover
(hogs head) off last week for pedal bushing repairs, never missed a beat prior to this problem".
The car in question had a Texas T Parts oil line with the oil scoop installed on the side of the hogshead. There are four screws holding the outside scoop and each screw was drilled and tapped into the hogshead to affix the scoop. One of these screws was long enough to contact the outer perimeter of one of the magneto field windings grounding it out. Simply loosening the screw fixed the problem. The car owner contacted TTP and was informed they were now supplying shorter screws with the outside oil line kit to prevent this problem.
If you have one of these outside oil lines you might want to check this out?
Ron the Coilman.
I lost my magneto about ten miles out of San Angelo Texas on the Texas T Party last week on my '14. Switched to Bat on the fly and went to Paint Rock to see the Pictographs.
I looked under the hood when I got there and felt the knurled nut on the wire coming up from from the magneto that goes into the magneto coil box insulator. It was loose. Finger tightened it. Back to magneto. Even though the brass connector is sitting on the post it needs to be at least finger tight.
Texas T Party was a GREAT tour at San Angelo, Texas, and look forward to next year. Hope it is in the Hill Country, Sandra.....
Ken in Texas
I don't have that style, the pickup and oil line are the round brass type that has the small oil line tapped into the side of it.
L will check if l have a good contact, that is simple.
I did notice a small crack in that triangle insulator.
13 runabout has the problem, 26 has new engine just waiting for another non bent exhaust manifold.
Q/ silicone is not conductive is it?
Nope, but it is corrosive to electrical wire and components.