Coils wont buzz on a 1913

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Model T Ford Forum: Forum 2018: Coils wont buzz on a 1913
Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Wednesday, February 21, 2018 - 09:58 pm:

Neighbor asked me to help him out with his 13.
By memory it doesn't run on mag, only battery.
He doesn't start it much but it was running a few days ago however today it wont go and we noticed the coils wont buzz no matter what we try.
Battery charged and good.
Using a digital meter (all he has) we have 7v going into coil box plus into ignition and coming out of ignition (bottom of coil box) but only when the key is turned to Batt.
When key is on there is 7v on engine side of each 4 firewall leads and 7v at each wire on the timer.
So if one live wire at the timer (key on) is shorted out will that activate the connected coil to buzz? We tried this and it doesn't. We only tried one coil.
What are we missing here?
Can all 4 coils fail at once?

Thanks


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thomas Mullin on Wednesday, February 21, 2018 - 11:02 pm:

Kevin,

I don't have a 1913, but on my 1916 the switch key connects the bottom strip in the coil box to either Magneto Hot or Battery Plus +. The timer completes the circuit by connecting each coil in turn to Ground (Earth). When the timer roller touches the segment in the timer, that lead is grounded and the circuit for that coil is complete - the coil should buzz on battery.

Possible things to look at are:

1. The inside of the timer - is the roller good? Is it really dirty?

2. Are the wire ends at the coilbox snug?

3. Are the coils fully seated in the coilbox? Do they touch the bottom contact strip? Do the side contacts touch both of the side contacts at each coil?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Thursday, February 22, 2018 - 12:29 am:

Let me get this straight.
You say that there is 7 volts at the timer yet when you connect the timer lead to ground there is no buzz. You have only tested one coil.
Well one coil can fail but it’s unlikely that all four fail at the same time.
One problem with digital voltmeters is that they draw very little current and a high impedance such as very poor contacts will pass enough current to operate the meter but not the coil.
So you need to go thru each item very carefully, check all four coils out of the coil box. Then do the same with them in the box. Finally check they operate when the engine turns.
Probably two of these tests will fail, but just go guru it carefully and you’ll get it operating.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, February 22, 2018 - 01:11 am:

So what you are saying, if you crank the motor over none of the coils buzz. Try cleaning all the points and timer. The points can oxidize just sitting and the timer may just be dirty.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Thursday, February 22, 2018 - 03:06 am:

Eureka guys we got it sorted.
Thanks for your feedback, this was a new problem for me. I will answer each point to help any future problem solvers.
Thomas -
1.The inside of the timer wasn't the issue as there was no buzz when a wire was shorted at the timer bypassing the inside condition
2. There was 7v at the end of the wires at the timer suggesting good connection on the firewall. These were tight connections when checked.
3. Coil connections faulty in the box, i'm guessing 7v wouldn't get to the timer if this was the issue plus was running fine 2 days ago. Surely a good place to check though.
Tony - I agree all 4 coils failing at once is unlikely. Your right on the money with the digital not drawing much and your suggestions are very close.
Mark - Your correct about the points oxidizing etc but it didn't matter if there was no timer even fitted. Once one of the timer wires is earthed that coil should buzz. Hence no need to crank the car until we could get a buzz via the direct short method.

Solution - We removed one coil and tried to test it with jumper leads from the in car battery...nothing.
So we thought perhaps the battery we thought was in good condition was mostly flat but just enough to put out 7v to a digital meter? We hooked a 6v battery charger to the one coil and it buzzed it's head off.
So assembled the timer back on the engine, Hooked the 6v battery charger to the in car battery, Key on and all 4 coils buzz as intended as the crank turned. Car fired up after a couple of cranks!
Being a 13 no generator, plus magneto doesnt work so every time the car has been run it's been on Batt so it drains the battery.
With no lights or starter motor as tell tales the low battery sneaked past us.

I hope this post helps someone else

Thanks
Guys


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Thursday, February 22, 2018 - 10:32 am:

Have you switched to "mag" after the motor starts ? Weak magnets or too much gap owing to a worn rear main at the crank flange won't allow starting on mag, but will run once started.

Sounds like faith healing, but I have had motors that wouldn't run on mag "get better" after running for a while and run when switched over. You might consider charging the magnets as per the Ford manual instructions for charging magnets in the car.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, February 22, 2018 - 10:44 am:

Kevin, if you find that the magneto is weak but puts out seven volts or more, or if you charge it so that it will, you can easily use it to keep the battery charged. No generator needed. Info is here:

http://dauntlessgeezer.com/DG102.html


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, February 22, 2018 - 11:12 am:

Glad you got it running. Sorry but I can not get my head around if you get a 7 volt reading, does not matter if digital or analog meter reading, how the coils could not fire. Even if the battery was low, the coil amp draw is very low. I would suspect that the contacts on the coils are dirty and when you used the leads from the charger you rubbed a little bit and made better contact.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Thursday, February 22, 2018 - 11:23 am:

Mark, a digital voltmeter will require about 0.00001 amps (10uA) while a coil requires about 1.3 amps to operate. It is clearly quite possible for a “flat” battery can work on a digital voltmeter but not supply a coil which requires 100,000 more current :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, February 22, 2018 - 11:32 am:

So what you are saying is you can have 7 volts but not enough amps? Never mind.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, February 22, 2018 - 12:14 pm:

I tried to edit my post but took too long.
If a battery is 6 volts and rated at 60 amps, and is fully charged, how can it not have at least the 60 amps? I can not put into context the tiny draw on the digital meter and how it would affect the reading of the battery. While I can visualize mechanical things, the little electrons bouncing around and numbers relating to them leave me lost. Numbers spoken or printed are just a jumble for the most part, now put a meter in my hands that I can read I can somewhat grasp the concept. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry & Sharon Miller, Westminster, CO on Thursday, February 22, 2018 - 12:47 pm:

Mark,

You are mostly correct on a battery being fully charged, should be able to supply the rating.

In the above case, there was an appropriate voltage but the battery not being fully charged, could not supply the amperage.

To further confuse things; batteries are rated in amp/hours. This means the battery will supply xx amps for yy hours. If a battery is rated for 60 amp/hours, it will supply 60 amps for 1 hour OR 30 amps for 2 hours, OR 10 amps for 6 hours.

Do not confuse CCA (cold cranking amps) for this amp/hour rating. CCA is mostly a marketing ploy. There are many factors affecting that rating, the sellers do not want you to know.

Digital vs analog meters. A digital meter takes very very little to operate. Thus, a digital meter can read 7 volts on a nearly dead battery. An analog meter takes more juice to operate and will act as a "load" on the battery. To adequately test a battery, a load must be applied to draw a large amount of amperage. Then the voltage must be measured to determine what condition the battery is in. If the voltage drops quickly and/or does not bounce back quickly the battery is not fully charged or is showing it's age. This is the same as what an analog meter does, it places a load on the battery that a digital meter does not. With that load, you will see a greater change in the voltage if the battery is not good or fully charged.

I hope I explained that in terms that are identifiable.

Good Luck,
Terry


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Thursday, February 22, 2018 - 05:25 pm:

The test with one coil removed from the car and directly connected to jumper leads from the in car battery would not buzz the coil but when the jumper leads were removed from the in car battery and connected to a 6v battery charger on the bench the coil worked properly. The sole cause for this issue was too flat of a battery, there was no connections loose/dirty.
Has been an interesting exercise.

Steve & Rich - its not my car and the owner reminded me it doesn't run on mag. Once we had the car running for 5 mins at fast idle jacked up and in top car I switched it to mag and the motor died, not kept running a bit rough as I have seen before but turned off.
History - He bought the car sight unseen from Kentucky I think. The USA owner had it restored and then sat in a showroom on display for many years. It runs fine otherwise.
The current owner has only been around the block about 3 times since he has imported it 3 years ago and perhaps it has never been driven properly since it was restored?
Everything else has been done to a high standard so it seems strange the mag doesn't go unless they left the mag out when restored.
The other potential is the mag might kick in if the car was driven on a long run. He hasn't ever got plates for the car but is planning to get this sorted in the next couple of months so after that well go for a longer run.
Thanks again guys


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Thursday, February 22, 2018 - 06:46 pm:

Terry that did help a lot. Thank you taking the time to answer, esp the load thing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Menzies on Thursday, February 22, 2018 - 07:03 pm:

I don't think a 60 amp battery will supply 60 amps for one hour. It will supply 1 amp for 60 hours or 2 amps for 30 hours etc.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Thomas Mullin on Thursday, February 22, 2018 - 07:15 pm:

Amp Hours re sneaky. It isn't really that simple. The amp hours on a battery is calculated at a set discharge rate (or period of time. For example, the 100 Amp-Hour battery may be rated at 20 hours. That means it will produce 5 amps for 20 hours. Unfortunately, as the discharge rate increases the time to failure decreases faster

This link will describe it much better.

I think of it a bit like mileage on a car. You get 30 miles per gallon at 35 miles per hour. If you go a lot faster than 35 mile per hour your mileage will be a lot less.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry & Sharon Miller, Westminster, CO on Thursday, February 22, 2018 - 07:43 pm:

Mark,

You are welcome. It was my pleasure to help.

David,

If the battery is rated at 60 amp/hours, it had better make 60 amps for one hour or the manufacturer is lying. Which would NEVER happen! wink wink ;-)

We all know what the rating is said to be and what it is in reality are, most likely, different.

The amp/hour ratings are much more accurate in back up power supply batteries and large batteries like used in submarines. Engineering size and capacity are much more critical in those applications as opposed to a regular car battery.

Cheers,
Terry


Top of pagePrevious messageNext messageBottom of page Link to this message  By RICHARD GRZEGOROWICZ on Thursday, February 22, 2018 - 09:03 pm:

sakuze me,is it not the timer's job to supply a ground to the coil system? should any voltage be going to the timer?, correct? IM a knue b with the t but,something's missing here.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Thursday, February 22, 2018 - 09:21 pm:

When the key is on batt here would be voltage on any coil wire at the timer except the one which is grounded. If the timer is between contacts it would show voltage on each one of them. To test the circuit, ground one at a time each wire at the timer. The coil should buzz as each wire is grounded. If this happens when you ground each wire, but not happen as you crank over the engine, your problem is in the timer.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Menzies on Friday, February 23, 2018 - 12:15 am:

We are straying from the topic a little but here is a quote from Peukert's law, "A common misunderstanding Associated with Amp Hours. A common mistake is made when it is assumed that the 100 AH battery will also provide 100 Amps for 1 hour. It won't. In fact a battery of this type may only provide about 40 minutes of continuous 100 Amp service at best"

In the case of a battery manufacturer who specifies a 100 AH battery on five hour rate, the claim is that the battery will provide 20 Amps for five hours before dropping below 10.5 volts.


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