Magneto problem

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Model T Ford Forum: Forum 2012: Magneto problem
Top of pagePrevious messageNext messageBottom of page Link to this message  By Wesley Melo on Saturday, April 28, 2012 - 08:41 pm:

I am confused about why my recently rebuilt motor will not run on magneto. The first couple of times we switched from battery to magneto it ran for 10-20 seconds, then started backfiring and died. Now it will not run at all on magneto. When I check the pickup probe dismounted from the hogshead there is no continuity between the output screw and the probe body (which is correct I believe), but when it is mounted on the hogshead I do have continuity between the pickup probe top bolt and the motor body (which I think is not good). I took the body of the probe off the hogshead, and placed one probe of my ohm meter on the magneto field output, then the other probe to ground and I have continuity. I think I have a shorted out magneto field, but electrical issues quickly confuse me. Can someone help identify my problems with the magneto?

Thanks for any advice or assistance
Wes


Top of pagePrevious messageNext messageBottom of page Link to this message  By joe bell on Saturday, April 28, 2012 - 09:18 pm:

Wes, warm the engine up on battery, then disconnect the wire from coil box and hook mag post wire direct to it, if it runs fine you know short is in switch, if it runs like crap it is in the engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Saturday, April 28, 2012 - 09:23 pm:

Be very careful that the battery and magneto do not become connected otherwise your magnets will be discharged. Most likely your problem is a poor connection somewhere.

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Saturday, April 28, 2012 - 10:20 pm:

Wesley,
If you measure the resistance between the magneto output post and ground it should be about 1/4 ohm. If you did not look very carefully it would look like it is shorted to ground.

http://www.mtfca.com/discus/messages/118802/177985.html?1293029858

As noted above, check your connections and be careful not to short anything out or put power to the mag post.


Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, April 28, 2012 - 10:23 pm:

One end of the coils is grounded to the ring. So yes there would be continuity between the pickup probe/mag contact and the engine. Take your switch apart that sounds more like where you will find the problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wesley Melo on Sunday, April 29, 2012 - 01:47 am:

Thanks for the information so far, and it looks like I have some testing to do tomorrow. I appreciate all of the advice so far on trying to trace down the problem, and if anyone else can help me out, I would really appreciate any advice.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Garnet on Sunday, April 29, 2012 - 06:26 am:

Hello Wesley;

A good place to start would be to check the magneto post and see if there is AC voltage there while the engine is running on BAT. Don't use a digital meter - use the old analog style with a needle. If there's no AC there, then it needs further checking.

I'd also be interested in knowing if any wiring changes or new wiring was done in the car. Is there any way that battery power is (wrongly) being applied to the MAG terminal on your ignition switch. This will kill the magnetism in the magnets bolted on the flywheel. What condition is the ignition switch in (new, old)?

Happy Hunting!

Regards,
Garnet


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Golden on Sunday, April 29, 2012 - 07:57 am:

Wes, did you install the coil ring that came out of your engine or install a rebuilt coil ring in your new engine?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Gruber- Spanaway, Wash. on Sunday, April 29, 2012 - 08:03 am:

I'd try to add something but about all I can do with electricity is start fires!


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Sunday, April 29, 2012 - 09:43 am:

It seems there is much mystery in chasing down mag problems once the basics like mag-post trash are checked.

Last night, Jim Thode posted the following "If you measure the resistance between the magneto output post and ground it should be about 1/4 ohm. If you did not look very carefully it would look like it is shorted to ground. "

Great information! Thanks Jim. So, the needle almost goes across the scale, but stops just short. All these years of checking my comparing non-working mags and comparing to a working mag I was looking for the opposite effect which would be a needle only moving a slight amount.

I have a request- could Jim or someone knowledgeable in the correct usage of the analog tester post an image or short video showing where the needle should be with a working mag compared to a non-working mag. This would be a huge tip for many readers of this forum.

Thanks. John


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, April 29, 2012 - 10:11 am:

If you have another mag post, you might try it. I have found that with the oiler type plugs sometimes the probe is not long enough to reach the button on the top of the coil. A plug with the coil spring contact can be stretched out to make a stronger connection with the button. Be sure to test with an analog AC volt meter before doing anything else. If it still doesn't work, you likely have an internal problem with the magneto which could range from too much clearance between magnets and coils, weak magnets, or shorted or grounded coils. After making sure the post makes good contact, the next thing I would do if it still does not work, would be to re-charge the magnets in the car. Anything else requires pulling the engine.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthonie Boer on Sunday, April 29, 2012 - 10:12 am:

I think a good start is : After mounting the coil ring and flywheel, check the magneto output on an empty engine . Turn the engine as fast as you can , then you need to have about 4-5 volt Ac. If so, you can go on to put your engine together. And know that your coil ring and flywheel is working.
Toon
209R
211R


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wesley Melo on Sunday, April 29, 2012 - 11:43 am:

Wow, lots of information here, and I have my work cut out this afternoon in following up with all of these fantastic recommendations. To answer some of the questions posed, the coil ring is newly rebuilt by a quality source who has rebuilt lots of coil rings and has a very good reputation, so I struggle that the coil ring is the problem (but maybe it is). All of the wiring is new, purchased from a reputable dealer, and we have checked and double checked for correct installation, and everything checks out OK. The switch is newly rebuilt by a reputable person I found in previous posts on the Forum, and he has rebuilt other switches for me in the past without problems. We took the transmission apart last week and the magnets had magnetism and seemed to be OK although we did not take them off and recharge them since they were freshly re-magnitized within the last 3 months or so when we were putting the engine together. The gap between the magnets and the field was checked and seemed correct.

Anyway, thanks again for all of the great information and we will be using all of this later today in checking out what is going on. If anyone has anything further, please post it for all of us. I will post what we finally determine is going bad with this situation (if I can ever find it).

Wes


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, April 29, 2012 - 12:16 pm:

I recently had an inoperative magneto on a freshly rebuilt 1910 engine. It had three problems:

1. There was no contact from the magneto post to the coil ring. The reproduction magneto post (pictured on the left) was made so poorly it could never work. I replaced it with a good original one (right side in picture).



2. The switch in the Jacobsen Brandow coil box did not connect the magneto to the coils due to broken contacts. I sent it to RV Anderson and he repaired it.



3. The reproduction plug / magneto wire set did not make contact because the wires were not even soldered to the ends or even stripped properly. A few minutes of stripping and soldering fixed them.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Garnet on Sunday, April 29, 2012 - 12:41 pm:

First of all, set your meter on its lowest resistance range. Then ZERO your needle (with the leads held together tightly) using the adjustment pot. If it won't zero then it's time to replace the battery.

With the meter on the lowest range, this is .4 ohms:


I've collected vintage test equipment and ham radio gear for decades. The above scale is from a Bach-Simpson which isn't ancient but certainly vintage.

Regards,
Garnet


Top of pagePrevious messageNext messageBottom of page Link to this message  By R.V. Anderson on Sunday, April 29, 2012 - 05:23 pm:

Wes, it's fairly common for the mag to quit soon after starting up a new engine. What usually happens is that a bit of wire has come loose and shorted the mag. It's almost always found up at the contact somewhere. Pull the contact, then look all around the solder contact button. Remove the wire, button her back up, and you're good to go.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Colin Bowen Victoria Aust on Sunday, April 29, 2012 - 07:14 pm:

Wesley,
I would disconnect the wire to the magneto terminal and check the voltage there. If it checks OK then start looking elsewhere
I had a similar problem and blamed my coil plate that I had rewound. Car ran for about twenty minutes and then backfired and stopped. Three rewinds and a lot of cursing later I found the magneto horn was shorting out.
Hope this helps.
Colin


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wesley Melo on Monday, April 30, 2012 - 01:11 am:

Well thanks to all of the info on this thread, we have been able to determine that the magneto is indeed performing to expectations, and that the problem is in either the wiring or the coil box. First we ran a number of the tests in the thread listed above, and all checked out well. Then we ran the "John Regan simple magneto output test" found in another thread on the Forum. The AC voltage at engine idle was 9.5 volts. After wiring the 1156 light bulb on the magneto post and to ground, it stayed lit and bright all through the test, getting brighter at increased engine speed. Under the load of the 1156 light and at idle the magneto put out 5.8 volts, and when we increased engine speed to about half speed the voltage read 9.6 volts, and with the engine running at high speed the voltage read 12 volts.

After checking out the ignition switch, which checked out OK, we decided to change it out with our spare anyway, but nothing improved and the engine would still not run on magneto. So we changed out the coils and after that when we switched to magneto, the engine did run, although it ran very rough with lots of missing and some backfiring. Sounds to me like we are losing voltage somewhere in the wiring or the coil box, so I am going to order new wiring tomorrow as well as the plastic coil box sold by John Regan's company. I think the plywood coil box may be the problem given what I have read on other posts on the Forum.

Hopefully we are on the way to fixing this problem, and I want to thank everyone for the information and assistance. I will sleep a bit easier tonight since it looks like I will not be pulling that engine from the chassis once again, at least not in the near future.

Thanks again to everyone for your assistance. And if anyone analyzes the above test results differently, please let me know your thoughts.
Wes


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Monday, April 30, 2012 - 02:05 am:

Wes,
Two additional thoughts.

Your voltage reading of 12 volts at speed sounds low. All I have read indicates that the high speed voltage should be in the range of 25 to 30 volts.
http://www.mtfca.com/discus/messages/50893/58808.html
Did you measure the mag voltage when running on the mag? Coils will work good on a HCCT on 2 volts but I don't know how that translates to real operation in the car.

Second, I have read that coils that may work well on battery power may not work well on mag power if they have not been checked and set on a HCCT.
Were your coils checked on a HCCT?

Others may have more experience with lower voltage mags and poorly adjusted coils.

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jem Bowkett on Monday, April 30, 2012 - 02:13 am:

12v is not enough. A good mag produces up to 30v.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Monday, April 30, 2012 - 06:35 am:

And would likely blow the 1156 bulb.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Monday, April 30, 2012 - 06:39 am:

The bulb should have blown- at higher speed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Monday, April 30, 2012 - 06:40 am:

Hal & I were typing at the same time.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Dimock, Newfields NH, USA on Monday, April 30, 2012 - 07:33 am:

If you have an outside oil line make sure the fitting on the mag post isn't shorting things out


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wesley Melo on Monday, April 30, 2012 - 04:39 pm:

Well Jim, after reading your email above and communicating with a friend, Ken Lauderback in Portland, I decided to call Ron Patterson, and after telling him the voltage readings he immediately agreed with your evaluation and told me I have a "puny" performing magneto. So my challenge is back to the magneto. He suggested an in frame recharging of the magnets as my next step before having to pull the motor AGAIN, so that is what we will do next.

Incidentally, I had all of my coils tested by Ron several years ago and I know he uses a HCCT. I may be sending some back to him for another test should the recharging of the magnets not fix the problem. I have a feeling that something happened during the installation or wiring of the motor that caused the magnets to become partially discharged. Ron thought the key switch could be the culprit, and we have changed the previous switch out for another newly rebuilt one, but who knows for sure!!!!

Thanks so much for your comments as well as the other comments that have gotten me to understand better what is going on with my motor. This Forum is fantastic for all of us trying to better understand the complexities of our hobby, and I really appreciate everyone's input.

Wes


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Monday, April 30, 2012 - 07:40 pm:

Hey guys - before you hook any wiring at all to a coil box that provides a place for both magneto and battery connections - you need to check that box and switch wiring. Connect an ohmmeter or light bulb and battery or any other means of determining continuity (connection path) directly to the 2 coil box connections at the rear of the coil box. These are the 2 lowest connections that have ceramic insulators on them. Now move the coil box switch on the front panel to ALL 3 positions repeatedly while watching that meter or bulb. Even the slightest flicker indicates something is wrong. These 2 connections should never be connected for any position of the switch including overtravel points beyond the normal arc path of the switch. Check very thoroughly and repeat the movement of the switch many many times to make totally sure that all is OK. If you service the switch or wiring inside the box, repeat the test. It only takes a minute or 2 and it saves hours of work and possible damage to your magneto if there is a problem. If you don't understand what this is about - don't be shy - speak up and we will cover this point again and again until you understand it because it is really that important.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, April 30, 2012 - 09:35 pm:

Here is a sad tale. It might not have happened in your case, but I had an engine which had just been rebuilt. It ran for an hour or so on mag and then it just quit! I switched to battery and it ran fine, but would not run again on magneto. It was fortunate that I had a mag oiler, because about 10 years later, I had rewound a magneto ring and I decided to pull the engine and try to fix the magneto. What I found was a shocker! The funnel on the end of the inside oiler was laying in the bottom of the crankcase. Only oil was what could get into the line without the funnel and the outside oiler, but it ran for 10 years that way and I took some one week tours all on battery. The funnel, when it came off must have cut the copper coils on the mag ring, because one of them was cut and that is why the mag quit working.

Now it runs great with the rewound magneto and recharged magnets.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wesley Melo on Tuesday, May 01, 2012 - 12:02 am:

OK Norm, you may have just solved how my magneto got de-magnetized. When we rebuilt the motor and transmission, we used a new inside oil line that had a larger funnel than the old style inside oilers have. We thought that would catch more oil, but when we re-opened the transmission last week and got down to the oil tube funnel, we found that the funnel had been rubbing against some of the bolt heads holding the magnets as well as on the side of the funnel where it rubbed against the magnets themselves. The funnel was severely ground down both on the sides of the funnel as well as at the bottom of the funnel where the bolt heads had rubbed. There was quite a bit of steel particles on the magnet that comes with the oil filter screen one puts inside the transmission cover. I am thinking this is what shorted out the magnets somehow. Your thoughts?

I am also suspect of the ignition switch, although it is newly rebuilt. And we have replaced it with another rebuilt one just in case it was the culprit.
Wes


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Tuesday, May 01, 2012 - 10:53 am:

If one uses the repro oil tube, it needs to be double checked for clearance as some do not follow the original shape. Quite simple to check for clearance and not just bolt stuff together and hope for the best !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Tuesday, May 01, 2012 - 12:35 pm:

Wes,
You have me confused now.

Did you get your oil funnel problem fixed? Did you replace the line/funnel and/or get the existing on attached correctly?

A low voltage mag output is probably more likely caused by too large of an air gap between the magnets and mag plate or weak magnets then a shorted magneto. You may be able to recharge the magnets in the car but it is harder to correct the air gap.

Another comment, it is common for the magnet in the hogshead filter to be fuzzy with collected metal small bits. Even when there is not a problem someplace in the engine.

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson-Nicholasville, Kentucky on Tuesday, May 01, 2012 - 04:30 pm:

Wes
Bingo.
Ask Jack S. where he got that oil line/funnel.
Ron the Coilman


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