Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
nsbrassnut
Posts: 42
Joined: Sun Jan 06, 2019 5:30 pm
First Name: Jeff
Last Name: Lee
Location: Nova Scotia

Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by nsbrassnut » Tue Jul 30, 2019 8:16 pm

Hi All

I recently went through a magneto failure issue that I think others have experienced in the past as well.

My recently restored ’15 Canadian Torpedo ran just fine on magneto through the recent PEI Red Dirt Tour. But when I wanted to go on my solo drive for Sunday morning coffee the magneto suddenly quit 2 miles down the road. Switching to battery it still ran fine, but as a caution I turned around and headed back home and parked the T.

Testing later in the day confirmed it was the magneto and not wiring or switch. It still has magneto headlights and I have an AC volt meter. The magnet showed erratic output with the lights cutting in and out and voltage up and down.

Pulling the magneto post I saw a wire at the coil pad that I didn’t remember from putting it together but didn’t want to take the chance pulling on in case it was connected to something.

So off to Google and the MTFCA forum archives to see what others had run into when having similar problems. Reading a few threads I eventually found some encouraging comments from R. V. Anderson in one of them. He noted that magneto failure in recently rebuilt engines was not unusual (mine had only 200 miles). He went one to describe that the most common problem was a bit of wire breaking off somewhere and usually getting thrown to the magneto output post connection. The fix was to pull out the wire and then keep on going.

So tonight that is what I tried. I took the output post back off and pulled out an inch of bent tie wire. I looks like some of the wire that I used to hold the bands together during installation (I know, not the best method).

Turning on the fuel, priming with choke and a cold pull on the crank with the switch on magneto resulted in a couple of coughs in the engine. Switch to battery it fired right up and then going back to magneto it ran just fine and the magneto lights are burning steady (but still not overly bright).

So a big thanks to the MTFCA forum archives and R. V. in particular for the good advice.

Drive Safe

Jeff
Nova Scotia
Canada


Chad_Marcheese
Posts: 102
Joined: Tue Jan 15, 2019 6:06 am
First Name: Chad
Last Name: Marcheese
Location: Upstate, NY
Board Member Since: 2005

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by Chad_Marcheese » Tue Jul 30, 2019 9:10 pm

Jeff,

I too encountered a similar problem, caused by me. I pulled the hogs head, and used a couple of small strands of copper wire (from a small 14 gauge wire) to hold the clutch pivot fork in position while lowering the hogs head. It was very small and thin, non magnetic which I thought would be good, and worked great! So I thought. Apparently on removing the strands of wire, I missed or dropped a strand. A couple days later, the mag doesn't work.

I probably did a forum search same as you and asked a question or two, but ultimately, I pulled the post back off, and was in disbelief that it couldn't be that simple. One little strand of copper wire shorting out the mag. I recognized the wire because of its size and length and knew precisely where it came from. Pulled it out, put the mag post back in, and everything was back to normal.

I really like those easy fixes, but they can be real head scratchers trying to figure them out.

User avatar

Steve Jelf
Posts: 1929
Joined: Fri Jan 04, 2019 9:37 pm
First Name: Steve
Last Name: Jelf
Location: Parkerfield, Kansas
MTFCA Number: 16175
MTFCI Number: 14758
Board Member Since: 2007
Contact:

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by Steve Jelf » Tue Jul 30, 2019 11:09 pm

(but still not overly bright)

Yes, they're magneto lights. :) Almost adequate in town where there's street lighting, too scary and dangerous on dark country roads. It helps to have actual magneto bulbs, no longer made but available at swap meets and auctions if you're lucky.
The inevitable often happens.
1915 Runabout
1923 Touring


Piewagon
Posts: 35
Joined: Thu Jan 10, 2019 8:38 pm
First Name: John
Last Name: Regan
Location: St. Charles, IL
MTFCA Number: 0
MTFCI Number: 77
Board Member Since: 1999

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by Piewagon » Wed Jul 31, 2019 2:12 am

The 15 and 16 cars with magneto headlights are driving with a known problem that Ford didn't solve until later when he added the "dimmer coil" about the same time he changed the horn button to the "Combo Switch" so that he could have horn button and light switch combined. I personally don't think it wise at all to use actual magneto bulbs. There are 2 reasons. One is that correct original magneto bulbs are 9V bulbs and are wired in series so if either bulb burns out you have zero lights instantly. Trust me on a dark night that event will get your heart started. What makes matters worse is that REAL magneto bulbs are rare and getting more rare. The most commonly used "magneto bulb" is a 12V bulb which doesn't burn out as easily but also are destined to be dim at all engine speeds below really high RPM driving. The 1196 bulb is most often used since it is a 12V modern bulb that is available but you have to be careful which filament your bulb has since the correct filament needs to be the "teepee" shaped type rather than the simple long horizontal "tie bar" kind which will not focus at all. There is a formula that will tell you the average life change amount based upon the voltage actually applied to the bulb versus the design voltage of the bulb. It will show you that tungsten filament bulbs that are operated at a different voltage than their design voltage will in fact have a radically different life expectancy with even small changes in that voltage. A 12V bulb operated at 6V will last about 4096 times the normal life of the 12V bulb - YES THAT LONG. It is why Edison's light bulbs at his Florida home have been burning for something like 100+ years. It is NOT because his bulb design was so great but rather because they have turned the voltage on the bulbs down to just a "glow" and thus have extended the life dramatically. But if you operate a 6V bulb at 12V you will get then 1/4096 times the normal life - YES you get normal life hours multiplied by .000244 which means your 6V bulb will just about turn into a flashbulb due to its radically shortened life but the time IS predictable. On later cars operating a 6V bulb on 8V by setting the generator up higher will end up giving you only about 3 to 5% of the normal life IF the generator is set to the normal charging voltage of about 9.4V and the usual charging would have been 7.05 for the 6V system. The ratio is then 7.05/9.4 = .75 then raise .75 to 12th power and you get .03167 now this only applies to tungsten filament bulbs but most halogen bulbs ARE tungsten filament. Better to wire your headlights in parallel and run then off the battery on a '15 or '16. The wiring can be made to look original since the parallel jumper can be inside the connector for each side. Now if a bulb burns out you still have a good headlight. I also recommend you add a driving light and brake light at the rear of the car. I rarely drive my T at night around here since too many fast cars and T is too hard to see at night. Play it safe.

User avatar

ABoer
Posts: 49
Joined: Mon Jan 07, 2019 2:41 pm
First Name: Anthonie
Last Name: Boer
Location: Klaaswaal NL
MTFCA Number: 19790

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by ABoer » Wed Jul 31, 2019 5:06 am

IMG_0831.JPG
I never use steel wire for the transmission bands !!
Toon

User avatar

George House
Posts: 562
Joined: Sun Jan 06, 2019 5:25 pm
First Name: George
Last Name: House
Location: northern Caldwell county TX
MTFCA Life Member: YES

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by George House » Wed Jul 31, 2019 11:10 am

Thanks for sharing about your experience, methodical Forum archive search and recognition of R.V.’s advice. All my T s run on mag - for now. But they probably won’t in the future so now I’ll know the first step....
I’d Rather Suffer Much In Good Company Than To Live Comfortably With Delicate Men..

User avatar

Steve Jelf
Posts: 1929
Joined: Fri Jan 04, 2019 9:37 pm
First Name: Steve
Last Name: Jelf
Location: Parkerfield, Kansas
MTFCA Number: 16175
MTFCI Number: 14758
Board Member Since: 2007
Contact:

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by Steve Jelf » Wed Jul 31, 2019 11:22 am

I'll add a little to one of John's comments. While some of the bulbs sold for magneto use are 12 volt, I bought some alleged magneto bulbs that turned out to be 24 volts! You could see them glow, but that's all you could see with them. They would certainly last forever, but they would be useless while doing it.
The inevitable often happens.
1915 Runabout
1923 Touring


Topic author
nsbrassnut
Posts: 42
Joined: Sun Jan 06, 2019 5:30 pm
First Name: Jeff
Last Name: Lee
Location: Nova Scotia

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by nsbrassnut » Wed Jul 31, 2019 6:25 pm

Hi All

In regard to the magneto lights. I agree with all the comments above.

I wanted to start with my T near bone stock and see what that was like. The magneto lights are not part of the longer term plan, but for now no night time driving is planned. Before night time driving is planned, the lights will be upgraded to 12v and powered from the auxiliary battery in the trunk for better performance and reliability. This will be on the completion and tune up list for the winter.

I also ran into the issue of ordering magneto bulbs and received 24v bulbs. They glow, but are not as bright as the right bulbs would be.

Drive Safe
Jeff


24tcoupe
Posts: 9
Joined: Sat Feb 09, 2019 3:00 pm
First Name: Laird
Last Name: Powers
Location: California

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by 24tcoupe » Sat Aug 31, 2019 8:56 pm

If I turn the key to mag, the car runs but runs rougher than on battery. It used to be the opposite. It ran better on mag than the battery. I cleaned the post off and re-instaled it. Same situation. The coil boxes were rebuilt about 5 years ago. Any ideas?


Topic author
nsbrassnut
Posts: 42
Joined: Sun Jan 06, 2019 5:30 pm
First Name: Jeff
Last Name: Lee
Location: Nova Scotia

Re: Magneto failure solved, thanks to the Forum archives and R.V. Anderson

Post by nsbrassnut » Sun Sep 01, 2019 4:19 pm

Try shining a flash light in the magneto post and look for a piece of metal caught up around the contact pad on the coil assembly. When mine failed, the removable magneto post was clean. The piece of tie wire was caught on the side of the magneto contact pad inside and could just be seen with a light then pulled out with needle nose pliers.

Good luck.

Post Reply Previous topicNext topic