Last July I was sitting at a stoplight, running on mag, when the engine died. I switched it to battery and started it right up, but when I switched back to mag it died again. I started it on battery again and waited for the light to turn green. After I got through the intersection and was going down the road I switched back to mag and it ran just fine. Been running on mag ever since.

Today I was driving along about 30 mph, on mag, and the engine died. I switched to battery and it ran, back to mag and it quit. I drove it home on battery. Now it won't run on mag. I haven't checked anything yet, so I don't know what happened. Any ideas?

Jeff - could it be the ignition switch? Or maybe a loose wire in the coilbox?

Mike

Jeff,Mike's idea sounds like a good place to start. Most old fashioned Mechanics suggest you trouble shoot from the obvious (frequently the cheapest in time & dollars) places to the more complex & irritating places(engone removal)If Ron The Coilman jumps in he will most likely have a good order of trouble shooting. He is very knowledgable on the electronic of this car. Good luck on getting the Mag back on.
Edward R. Levy

A weak spring in the contact of mag pick up will sometimes let the contact jump off the mag ring solder jouint and then mag doesn't work. Try recentering it first and clean it off while you have it out.

Jeff-
takethe magneto connection of the engine. There often will be a lint/fuzz build up that will short-out the magneto or otherwise make it not work.

Look for the easy things first...
-Keith

A voice from the wilderness.
Has anyone checked the crankshaft end play?
Ron the Coilman

jeff, i had the exact same thing happen to me on my '26, it turned out to be a gooey,gob, of junk, hanging off the end of the mag terminal, i cleaned it up, put it back in and it has run fine on mag ever since!!!!1, (it's an easy check to start with anyway) just my .02.
den

hey jeff, did you find out what the problem was ?
den

I finally got out to the garage tonight and removed the mag post and found a piece of metal about a quarter of an inch wide and about an inch and three eighths long with a bunch of shiny spots on it. It is most of the side of one of the wear shoes that fit inside the brake drum for the clutch plates to ride on. Has anyone else had these fail like this? I got it out and the engine runs on mag again, but I wonder how many more have failed and how many more are floating around in there?

I had that happen twice so far. I just take out the piece with a strong magnetic tool and keep driving.
I have new parts to fix the transmission, but I am not inclined to do it as long as everything works fine.

I'm glad I did a search rather than create a new topic. We're new T owners with just 2 weeks under our belt in our 26 roadster. Car has been restored but seldom used since. I took it for a spin today since getting advice I'd posted for under "shudder when going from low to high" and was practicing my spark, throttle & pedal technique. Today when I switched from battery to mag the engine died as the original poster. Back to battery and it fired right back up. We also had a second issue. On that road trip I stopped for gas. Got back in only to no power to ignition. The lights would come on so power was coming from the battery. Checked with my limited T knowledge for anything loose under the hood and about the time I was making the call to AAA, I gave it another try and it fired right up. Still wouldn't run on mag tho. Prior to today the car ran great on mag.

Sounds like you might have trouble in your ignition switch. You can send it to Ben Martin,Tucker Ga. He does a good job on them. Contact me if you want address.

Gary,

It sounds like you may have an ignition switch problem, or a loose wire on the switch or ammeter. It's not hard to remove the mag post and check to see if there is anything shorting it though.

Since I posted about the lug shoe piece shorting my mag post last year there have been many others experiencing the same failure. There have been a few discussions about them on this forum. Unless your transmission has been rebuilt within the last few years, this probably is not your problem, since it seems to be the lug shoes that have been made in the last few years that are failing.

Don't get discouraged with your car. It sometimes takes a while to sort out all of the bugs after a T has been sitting for a few years. They really do like to be driven.

I'm about to head out to the garage to check connections on the backside of the ign. switch as well as the mag post. I'll post my findings, if any.

We've wanted a T for the last 20 years or so. Looked at and came close to a couple. A beautiful 21 roadster and the other a 1914 speedster over the years but always opted for something else. We recently sold our 1960 El Camino and decided it was time to make the T plunge. We won't get discouraged. Thru advice offered in this forum, I have pretty much gotten my "low to high" shift technique consistently smooth. I'm sure I can work my way thru the mag issue.

Thanks!!

Gary:

If your lights work and show as a discharge on the ammeter than the battery to ammeter wiring is OK on both sides of the ammeter and the ammeter to ignition switch wire is OK at both ends too. Your trouble then lies within the ignition switch contacts that provide connection between the MAGNETO and coil box when in the MAG position or BATTERY and coil box when in the BAT position or both. Be carefull in your testing since an accidental connection between the BATTERY wire and the MAGNETO wire will result in your magneto magnets on the flywheel being discharged and/or your magneto ring being damaged. The magnets can be recharged without pulling the engine but the magneto coil ring must be removed from the engine to make repairs to it.

First thing I did was checked the mag post for debris. I'm assuming I checked the right part. The needle end of the post was clean and the connection was tight. Checked all the connections between the battery, cut off switch, ign switch and everything under the hood. Some wires were slightly loose but all appeared to be making sufficient contact. Anything loose was tightened. Turned on the fuel, the cut off switch, turned the key on, press the starter button and nothing. Try the lights, they came on and showed a draw on amperage. I noticed even slight wiggling of the light switch would cause the lights to go out. Lights on or off the starter still wouldn't crank. Off and on with the cut off switch a few times and eventually it cranked. Shut it off and it started back up fine.
Took it for a spin, switched it over to mag and it ran as sweetly as before. Get back to the garage, shut it off. This time it starts right up but won't run on mag again. As strange as it may seem I may have two defective items that went bad simultaneously. The battery cut off switch and possibly the ign switch. It may just be the battery cut off switch because at times with the key on, I'd hear a clicking/buzzing before dperessing the starter button and at times I wouldn't. When I didn't hear it I'd leave the ign switch on, shut the cut off switch off then back on and the car would start. Sorry for rambling

Take that battery cut off switch and deep six it. They are a waste of time.

I certainly don't think the switch was intended as any sort of "anti theft" device, at least by todays standards as 99.9% of the general public wouldn't know how to drive off with the T anyway :-)That said, what is/was their intended purpose? And yes, I'll probably just bypass it for now and see how it goes. I'll update the thread with my resluts. Again, thanks for the help and encouragement.

It sounds as though you have several problems. The only thing the magneto has in common with the battery and lights is the ignition switch By the way, while you are checking or tightening the wires, be sure you don't get the battery connected directly to the magneto or you will discharge the magnets! There are two connections behind the ignition switch one is for battery and the other is for magneto. If you have the original wiring or type of wiring, the red wire goes to the magneto. On the terminal block on front of the firewall, the red goes to red and nothing else should be connected but two red wires. The other ends of the red wires go to the magneto post and the ignition switch. All connections here should be tight and no lint on the magneto contact inside the hogs head. The wire between the ammeter and the switch should also be tight. one of the wires behind the ammeter goes to another place on the terminal block where it is connected to yellow with black tracer which other end goes to the generator cutout. The other wire behind the ammeter is yellow and goes to the terminal block where the yellow wire to the starter switch is connected. You could also have a loose connection under the starter switch. You must also have a good connection on the top of the starter and at the battery. Take off the two cables at the battery and clean up the contacts and also the inside of the battery terminal connections and put them back on the battery and tighten. Now with all these things cleaned and tightened try again. When you turn the key to batt, the coils should buzz. Be sure to have the spark lever retarded when you do this. You might need to turn the crank slightly to get it to buzz Your starter sould turn over the the engine and it should start. Then switch to magneto and it should still keep on running. If it starts but won't run on mag after doing all the above, you need to check the output of the magneto. There are threads concerning how to do this with an analog voltmeter and a light bulb. Look up and see how to do that. Another possible problem is a low battery, but from what I have read above, I would think the probable cause is a worn ignition switch because that's the only item all of the above have in common.
Norm

Gary,

Jack's dead on with the cut off switch, ditch it. I had one that came with the car, thought the battery was shot, took the switch off & found the battery was perfect. As an anti-theft device they're worthless, what car thief is going to know how to drive one & a kill switch won't stop a tow truck.

Alex

Jack, Norm, Alex, thanks for the advice. I'll bypass the cut off switch tomorrow and pull the ignition switch out of the dash and check those wire connections. They seemed tight when reaching up from behind but I'll also give them a visual check. I don't think I have a wiring issue per se since the car was running sweet prior to this and I made no changes.

Gary,

While you are looking things over and are dirty anyway, pop the timer cover and clean the rotor and insides well. I found on my car the it would run fine on battery and poorly on magneto (this after recharging the magnets). Cleaned the timer insides of all the oil and such and it worked much better. I could even get it to crank start on magneto.

That ignition switch and its problems makes me glad I don't have all those frills on my 1916.

Tom

It has been my experience that those D!@# Battery Cutoff switchs CAUSE way way more problems than any other worthless accessory and they don't accomplish ANYTHING worthwhile. Since I am often involved in trouble shooting electrical stuff on cars, I run up against those things constantly and they are ALWAYS troublesome. Whoever came up with that contraption sure didn't do any favors to old car folks. If you need to disconnect the battery for a season or something, just loosen up and lift off one cable. Then clean the post and cable end when you reinstall it and you will then be just fine. That darn switch is just another in a long line of "fixes" for imaginary problems. 15 million Model T's were built WITHOUT them.

The ignition switch is not difficult to take apart. It will either be bent over tabs on the back or a bayonet type. watch carefully as it comes apart as spring loaded. Polish all the little round contacts and the places they contact. Gently bend up the springy thingys to make better contact and reassemble. Ifsome of the spring contacts are broken the vendors have repair kits. Good luck. John

I havn't had a chance to put in any garage time so still havn't disconnected the battery kill switch. I have cleaned/tightened all the terminals from the battery forwards. If disconnecting the cut off switch isn't causing me issues, my best guess it is the ignition switch. The switch itself is very loose as is the headlight switch. I've looked to see what the vendors are selling and if need be I'd rather have mine refurbished. The replacements all appear to be chrome and mine is brass, or brass looking. I may be e-mailing Jack D for his contact (no pun intended) in Georgia.

If this car has a starter and it will turn the engine over, your battery disconnect switch is ok. The starter draws more power from the battery than anything else on the car. I've had a problem with my ignition switch and bought a kit from the vendor. I don't remember for sure which but I think it was Chaffin's I had to do a little filing of the plastic parts to make it fit, but it hasn't given me any problems with either the ignition or the lights since I installed it. Before this happened, I had it running on Mag and it quit. I made the mistake of turning the switch to batt while it was still moving and when I did, the muffler blew apart. After the switch was fixed, it runs fine on either batt or magneto.

Norm

Ahha. When I purchased the car the first issue I had to deal with was replacing a blown apart muffler. The seller blamed it on not knowing how to properly run the car. Which may or may not have been the case.

My 25 did the same thing only it just blew of the tailpipe. The problem was in a small brass strip between two terminals on the back of the switch. I used a thin brass shim, drilled two holes first and cut it to shape. Laid it on top of old strip and ran small screws into the hollow tube of the rivet. Howevr the back of your switch may be different.