New T owner and a few questions

[MikeJB]

Hi all,

Actually it's my son Eric who has recently bought a 1923 Model T. He learned to drive it on the flats in Bakersfield, CA and then trailered it up to Frazier Park where driving is a bit more challenging because of the hills. He installed a set of Rocky Mountain brakes while still in Bakersfield.

I've been helping him troubleshoot some ignition problems and could use some advice. Initially the car ran fine on battery or magneto. The car has the original six volt setup. During a drive, running on mag, the engine abruptly died and he had to continue on battery. Back at home, he removed the magneto post and yes it was loaded with lint and debris. After he cleaned it the car would run on mag again...for a few weeks.

Further cleaning didn't help. He tried a bridge wire from the mag terminal straight to the coil box and it would not run. I'm sure he switched from battery to mag before using the bridge, with the engine running briskly. Then he did some flushing with diesel fuel, running briefly and then draining. That was done four times and it still won't run on mag, although it will now sputter a bit when switching from battery.

So we tried to test the mag electrically. An 1156 bulb lights brightly at a rapid idle and I think Eric said he'd measured the open circuit mag voltage to ground at 20V or more. Then we measured current directly to ground. We could not get a reading higher than 4.4 amps even at pretty high RPM.

This is quite mysterious since the car stopped running on mag abruptly, on a somewhat rough road, as if there were a sudden open circuit. But all connections have been double checked other than actually inspecting the mag assembly...not too eager to dive into that!

So does the 4.4 amp current limit indicate a likely problem? Should we consider an in-car magnet recharge?

We will be grateful for any help in sorting this out!

[MichaelPawelek]

I’ll let the real electrical gurus answer your questions but just start with two things. The contacts in the key switch can become worn/dirty over time so checking that you are getting great contact through the switch when turned to the magneto position is a must.

Second, be sure in all your diagnosing that the battery is never wired to the magneto either at the firewall or at the magneto post. If done the magnets will immediately loose their magnetism.

[John kuehn]

Welcome to the world of Model T quirks! From what your describing it sure sounds like it could be the switch. This is a common issue with the ignition switch.
It could be that the contacts inside the switch arent making a good connection when turning to the mag position. Without removing the switch from the dash turn the switch back and forth several times, Especially wiggle the key while in the mag position.
If it starts to run on mag and cuts in and out the contacts inside the switch need to be slightly bent outward to make a good contact. They are made of brass spring material.

Are you sure the magneto contact on top of the transmission is making a good contact to the lead coil ring contact? It’s not uncommon for the contact spring not making a good contact at that point. Also be careful to NOT run a battery connection to the mag contact. It will demagnetized the magnets. Any battery voltage doesn’t need to be connected to it.
Good luck and check the all the mag connections. Others will have opinions about the issue you have and they can help.
And be sure to buy the Ford service manual and other manuals that are available from the vendors. They will tell you what you need to know to AVOID doing the wrong thing to your T.

Remember your dealing with 100 year old technology and it’s not quite the same as your modern vehicles!

[John kuehn]

Here is an earlier form post and a good picture of the inside of the switch. http://www.mtfca.com/discus/messages/17 ... 1307332952

[TXGOAT2]

20 volts is not bad for a mag, and is plenty to operate the ignition system. Of course, voltage will fall off at lower engine speeds, but that's usually not a problem. 4 amps is more than enough to operate the ignition system, although that will also fall off at lower engine speeds. A magneto in top condition might develop at much as 30 volts at higher engine speeds, but most of them will test lower and still give good results. I think the advice given above concerning the ignition switch and mag post contact is pointing in the right direction. A internally weak magneto (weak magnets) usually will show up as difficulty when hand cranking the car on MAG, which goes away if switched to BAT. (This assumes the switch and wiring are working properly) Once started the car will usually run better on MAG, in part because the voltage available is typically higher than the 6 volt battery can deliver. Procedures for starting the engine on MAG and Bat differ somewhat, and If you are not familiar with the methods, I'd recommend getting some guidance. It's possible to damage the starter or get bones broken if proper methods are not followed. Like dogs and horses, all Model T's seem to be a little bit different in how they behave, and once you become familiar with the car, it becomes easier to start and run it. They're dependable cars if handled properly and kept in reasonabley good condition.

[Norman Kling]

From your description, I believe the wire from the switch to the coil is good. However, the wire from the magneto is either not making a good contact with the magneto post, the terminal block or the switch. If it were mine, after checking the voltage at the magneto plug, I would check it at the terminal block and perhaps clean up the contacts at the end of the wires. sometimes they get corroded or the contact is not making a good contact with the wire. Maybe a little solder where the clip is connected to the wire. If you get good voltage and current at the terminal at the switch, then you might need to clean up the contact inside the switch. Whatever you do, do NOT allow any battery current to flow into the magneto.
Norm

[Steve Jelf]

After a hundred years, sometimes the switch backing plate has become warped, causing intermittent contact. You can flatten it on coarse sandpaper. After flattening, you may need to deepen some of the dimples a little.

Some switches have backing plates held in by pins, like this one. Others have bent-over tabs. If you have one of those you'll have to unbend the tabs to get the backing plate out. While you have the switch apart, turn the tabs red and let them cool so they won't break off when you re-bend them.

[MikeJB]

Thanks all for the inputs. We are pretty sure that there isn't a problem with the switch because we have bypassed it with a jumper wire directly from the magneto post to the coil box input. Is it possible for something inside the coil box to come loose that affects running on magneto but not on battery? I thought that the coil box did not have any different circuitry between battery and magneto and it is only the switch that selects the input source to the box.

Also, Eric disassembled and cleaned the switch and it checked out fine with an ohmmeter. He got a new magneto post, which made no difference.

I wonder if this is a clue: When the engine was running on battery, Eric had one hand on the car body and with his other hand touched one of the wires (under hood) that is an input to the coil box. He got a powerful shock right through the wire insulation. I wouldn't have expected such voltage to exist at the primary side of the coils.

Going back to the first magneto failure, when Eric was driving on a pretty rough dirt road and the ignition abruptly cut out, that seemed to suggest a loose connection somewhere. But there aren't many connections and they have all been checked, except for anything inside the coil box. Should we try to inspect the internals of the box for anything shifted, loose or shorting?

[speedytinc]

You have the lid secured on the box? Does your lid have a sheet metal piece that presses down on the coil boxes to keep them in contact with the bottom contacts? Can the coils vibrate/move up away from the contacts is my point. Check for contacts condition. Tension & cleanness.

[Steve Jelf]

Is it possible for something inside the coil box to come loose that affects running on magneto but not on battery? I thought that the coil box did not have any different circuitry between battery and magneto and it is only the switch that selects the input source to the box.

You're right. On a 1923 the coil box has a single input from the terminal board.

A shock from a low voltage wire suggests that it may be too close to a spark plug wire (high voltage). Within ¼" that high voltage may jump the gap. I recently learned that from a Model T electric expert, and I suspect it's why my mag needs a recharge. I intend to pay special attention to keeping those wires much more than ¼" apart, more like an inch where possible.

[TRDxB2]

How is your coil box wired. Normally the MAG post on the box on a starter car is left out or not connected to the the center strip inside the box. So hot wiring to that post would do nothing. You can remove all the coils and test continuity from the MAG post to center strip inside the box and the same for the BAT post. The post with the continuity connects to the switch center, "coil", position on t he switch via the terminal block

[John kuehn]

Is the wiring on the car the original wiring or has it been replaced.
If every thing has been double checked with the wiring then the next thing to do would to remove the coil box and closely inspect it. The coil box has to be good electrically and if it isn’t you will have intermittent problems.
If you take it out you might can tell if the wood or bolts have been replaced. Eventually the wiring will need to be replaced and the coil box will need to be rebuilt. And especially if it never has. And if you rebuild the coil box use all the original contacts in it. The originals are the best. Hope this can help.

[DanTreace]

We are pretty sure that there isn't a problem with the switch because we have bypassed it with a jumper wire directly from the magneto post to the coil box input

If your had the T running on Bat from the switch and the Blue/Yellow common wire from the switch was still attached to the Coil Box at that common Porcelain standoff, when you placed the Red mag wire from the mag post to that common standoff, you can discharge the magnets on the flywheel.

Now if the T was not running, and you removed that Blue/Yellow at the common Coil box standoff, and then attached the Red mag wire, and tried the starter switch to turn the engine over, many T's can't be started on Mag only, as the low rpm from the starter only can't provide much volts from the magneto to fire all the coils.

When the engine was running on battery, Eric had one hand on the car body and with his other hand touched one of the wires (under hood) that is an input to the coil box. He got a powerful shock right through the wire insulation

That is odd, first guess is Eric also had his hand close to one of the lower Porcelain standoffs or the wires that carry the high voltage to the plugs.

If he indeed was only holding the Blue/Yellow wire from the switch to the Coil box common Porcelain standoff and got a shock, there is high amp voltage in that wire, should not be, should only be the low amp battery voltage. Could be that wire is against a spark plug wire, wires have to be separated to prevent cross-voltages. Or could be somehow high voltage is entering the dash switch, but can't think how. A full check out of the Coil Box should be done.

[TRDxB2]

Check your wiring from the diagram I posted above.

[MikeJB]

As far as I know there is a lot of clearance between the spark plug wires and any other under-hood wires. So it could be a real issue for high voltage to appear on the coil primary side and wonder if that could short to ground if there were too close a clearance between magneto and ground parts of the switch. If we have an consensus that high voltage should not be found on coil box inputs, we should try to track that down. Not sure that this coil box even has a cover so maybe there is a sneak path to be found inside the box.

Again, the shock occurred when running on battery. I wonder why such a voltage on the primary / coil box input would not short back to ground through the switch and the battery and generator.

I see you all are pointing to things other than the magneto itself, which is good to hear.

[DanTreace]

There should be no high voltage to the common strip at the bottom of the box. There must be an external contact somewhere or a real bad coil box.

The only way would be some kind of carbon arching from a poor wood box, carbon tracks in the split plywood used in original coil boxes that gets warped and decays overtime.

That is why the best way is to restore a coil box to new, to prevent any issues of that box that holds 4 trembler coils that can put out thousands of volts to those lower Porcelain standoffs!

Solder wire y.jpg (77.51 KiB) Viewed 4455 times

[John kuehn]

There have been issues with carbon tracking inside the coil box which would cause an intermittent miss. It might be possible that’s happening somehow with you magneto issue. The only real way to check would be to remove the wood and check out the wiring behind the wood. This is a guess of course but after being around the T’s I have just about anything is possible. And it usually turns out to be something simple when you find out what the issue is and especially if it’s something electrical !

[Steve Jelf]

Notice that in Dan's picture all the contacts are soldered to the bolts. That's a good thing.

[DanTreace]

Thanks Steve

Just when workin' on Henry's child, like to do the best for longevity....to keep the Ford running for another 100 years

[MikeJB]

Eric just informed me that his coil box has no lid! I wonder what's keeping the four coils in place?

We had better remove that coil box and go through it. I think we'd like to have it tested and tuned up or rebuilt if we don't find something right away.

The nearest big town is Bakersfield, CA. Should we expect to find someone there that deals with these boxes?

[speedytinc]

Eric just informed me that his coil box has no lid! I wonder what's keeping the four coils in place?

We had better remove that coil box and go through it. I think we'd like to have it tested and tuned up or rebuilt if we don't find something right away.

The nearest big town is Bakersfield, CA. Should we expect to find someone there that deals with these boxes?

Push em down & see if it runs. Could it be that simple? does explain hitting a bump & dieing.

[John kuehn]

If your son can change out the magneto post and clean up the ignition switch he can rebuild the coil box. I’m not trying to be a smart guy but it’s not that hard and fairly simple. There are plenty available diagrams and exploded views how every thing goes. Whatever you do good luck. There might be someone who rebuilds them but most T owners do it themselves.
Others may know or recommend someone. Check with a T club in your area.

[Norman Kling]

Another possibility:
Sometimes the coils are not adjusted correctly and will run on battery but not on magneto. So have the coils tested and adjusted by someone with a good coil tester. oR borrow a set of coils from someone whose car runs good on magneto and see how yours runs. The reason for this is that on battery, the current builds up the full time the rotor passes the contact. However, on Magneto, it builds up as the magnets pass the magneto coils. This could be caused by the coils out of adjustment, or by a dirty or worn out timer. The timer might not be set to make contact at the same time the peak voltage occurs on the magneto. However it might have points where you move the spark lever and the coils cut out and other locations of the spark lever where it will run. So try moving the spark lever to different locations to see if it makes any difference.
Norm

[TRDxB2]

....
I wonder if this is a clue: When the engine was running on battery, Eric had one hand on the car body and with his other hand touched one of the wires (under hood) that is an input to the coil box. He got a powerful shock right through the wire insulation. -----

Its important to add specifics to the statement about getting shocked. Note Voltages don't hurt as much as amps do.
One hand on the body and Eric is grounded - he should not get a shock through insulated wires unless the wire insulation is bad and grounding itself in other places.
Next: He touched one of the wires that is an INPUT to the coil box. There are 5 input wires, 4 from the timer and 1 from the switch (since on battery all would be battery voltage/amps), and 4 out wires to the spark plugs form the coils - high frequency voltage. How many posts are sticking out of the coil box?

Pictures of the condition of the wires, terminal block and coil box (inside and out) might help others see something amiss.

[TRDxB2]

....
I wonder if this is a clue: When the engine was running on battery, Eric had one hand on the car body and with his other hand touched one of the wires (under hood) that is an input to the coil box. He got a powerful shock right through the wire insulation. -----

Its important to add specifics to the statement about getting shocked. Note Voltages don't hurt as much as amps do.
One hand on the body and Eric is grounded - he should not get a shock through insulated wires unless the wire insulation is bad and grounding itself in other places.
Next: He touched one of the wires that is an INPUT to the coil box. There are 5 input wires, 4 from the timer and 1 from the switch (since on battery all would be battery voltage/amps), and 4 out wires to the spark plugs form the coils - high frequency voltage. How many posts are sticking out of the coil box?

Pictures of the condition of the wires, terminal block and coil box (inside and out) might help others see something amiss.

[Steve Jelf]

There's no tuning up the coil box. Just be sure all the hardware is making good contact with the coils where it's supposed to and there are no unauthorized grounds. I was going to recommend the MTFCA Electrical System book, but refurbishing or rebuilding the coil box is such a straightforward affair that the book doesn't even mention it. As the saying goes, it ain't rocket surgery.

[jiminbartow]

Check out, https://mtfca.com/phpBB3/viewtopic.php?t=17013. Could be a short if the brass fitting was tightened too tight. I don’t like this type of magneto post oiler fitting because there is not enough room for the oil to get up into the post housing and into the fitting opening. Jim Patrick

[MikeJB]

Hi all, just now back from checking some things on Eric's T. I have a few updates but want to thank everyone for the helpful replies.

Wanted to verify that Eric could get a shock from the coil housing input wire. He didn't think he had made contact with one of the spark output posts that are pretty near the input wire that comes from the ignition switch. Now I think he must have because I used a grounded wire to see if I could draw a spark when rubbing it all over the insulation of the input wire. Nothing observed and no misfire heard.

We are confident that the four coil boxes are in OK shape because the engine runs smoothly on battery. We again observed that the magneto will brightly light an 1156 bulb. We again tried a bridge wire from the magneto post straight to the housing input terminal, after starting on battery and then switching to off and also to magneto. This to avoid any contact with the 6V supply. All we could get is a few pops and spits, she would not run.

So we seem to be out of things to check other than the magneto coils and wiring, which won't happen soon. If there is an engine rebuild in the future that's when we would tackle it.

Eric is curious if we should try flashing the magneto with a 36V supply as we have read about but I'm skeptical that it would help. Reminder, when he bought the car it ran fine on both battery and magneto. A few months later as he was driving on magneto, it abruptly cut out and he had to continue on battery. He cleaned the mag post of lint and debris and it began to work again, for a few days, then failed again. He tried a new mag post, no good. For a magneto to abruptly stop working, a short or open circuit seems probable, not that the magnets somehow suddenly became weak.

Does anyone think a magnet re-charge is worth attempting?

This T has no oil feed fitting to the mag post, by the way, which was suggested as something to check.

[Norman Kling]

It might be a good idea to remove the hogs head and take a look inside. Also a good time to charge up the magnets one at a time. There are many posts on how to do this.
On one of my T's right after installing a rebuilt engine I was driving and all of a sudden it quit running. It started again on battery. I drove it for about 10 years and then I wound a few coil rings and decided to put a new one on this car. I pulled the engine and transmission and found the funnel off the oil line laying in the crankcase. The magnets has hit the funnel and broken it off and when that happened, it cut one of the copper strips on the coil ring and that is when the magneto stopped. Fortunately, I also had an outside oil line on that engine so it ran for 10 years without damage. After replacement and magnet charge my car which was one of the slower ones on tours, became one of the faster ones.
Norm

[MikeJB]

Norm,

I am interested in this but right now don't know what's involved with removing the hogs head. Can that be done with the engine still in the car? And will that allow enough access to actually see coil or conductor damage as you had seen?

[Steve Jelf]

He cleaned the mag post of lint and debris and it began to work again, for a few days, then failed again. He tried a new mag post, no good. For a magneto to abruptly stop working, a short or open circuit seems probable, not that the magnets somehow suddenly became weak.

I agree that working, then not working, then working again, then not, doesn't suggest magnets suddenly getting weak. I would bet on an intermittently broken circuit. Maybe a ribbon between coils, or at either end? That seems more likely in those places exposed to the force of splashing oil rather than inside a coil.

Yes, you can pull the hogshead in the car, especially if it's an open car where you can lift it out with a hoist. I don't know about a closed car. Maybe somebody who has done it can testify. I suspect it may be easier to just pull the engine.

But with the hogshead off you won't be able to see a lot of the coil ring. You need the flywheel/transmission off for that, which means pulling the engine.

[TRDxB2]

Initially you said that Eric " removed the magneto post and yes it was loaded with lint and debris" - what kind of lint and debris - from transmission straps, magneto coil insulation , other? Chttp://www.mtfca.com/discus/messages/411944/46 ... 1404921829

[MikeJB]

I didn't see the debris myself but Eric said it was a bunch of oily lint, supposedly being shed by the transmission bands.