Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 08-19-2019, 04:00 PM   #1
Conaway2
Member
 
Conaway2's Avatar
 
Join Date: Apr 2019
Posts: 77
Default Coil failure ?

As I was driving my 31 Model A home from the local gas station yesterday, the engine suddenly died. A little roadside diagnostic work suggested an ignition issue - confirmed later after being towed home.

Points and condenser were replaced several months ago, engine timing is right on. Although there is absolutely no spark, the ammeter shows deflection as the starter cranks the engine over - from the points opening and closing.

I suspect the coil, although I guess the condenser could be part of the issue as well - its an original style one installed in the original distributor.

The coil is an original one - almost 90 years old. IVe never had a coil failure on this car in the 50 years I have owned it.

Has anyone else experienced a sudden coil failure ?? Thoughts ??

Thanks - Jim
Conaway2 is offline   Reply With Quote
Old 08-19-2019, 05:26 PM   #2
Chuck Sea/Tac
Senior Member
 
Chuck Sea/Tac's Avatar
 
Join Date: May 2010
Location: Between Seattle & Tacoma
Posts: 1,772
Default Re: Coil failure ?

Well, it’s obvious the coil is trying to work, because your amp meters moving. Have you checked for spark at the coil wire to ground. Coils do fail, but not as often as people think.
Chuck Sea/Tac is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 08-19-2019, 05:43 PM   #3
Conaway2
Member
 
Conaway2's Avatar
 
Join Date: Apr 2019
Posts: 77
Default Re: Coil failure ?

yes - I pulled the high voltage wire out of the dist cap and held it close to one of the head nuts while cranking the engine with the ignition switch on - absolutely no spark. Also - after the first few seconds of cranking, the ammeter stops deflecting ‘normally’ each time the points open and close and starts swinging back and forth - showing discharge and charge- as if the coil is generating a back voltage - never seen this before. I suspect the coil has an internal short.
Conaway2 is offline   Reply With Quote
Old 08-19-2019, 06:50 PM   #4
Ed in Maine
Senior Member
 
Join Date: May 2010
Posts: 598
Default Re: Coil failure ?

Maybe the cutout opened up disconnecting the generator from the battery, the generator voltage goes high because it is not regulated by the battery and the excessive voltage overheats the coil and damages the coil windings. Ed
Ed in Maine is offline   Reply With Quote
Old 08-19-2019, 06:51 PM   #5
Purdy Swoft
Senior Member
 
Purdy Swoft's Avatar
 
Join Date: May 2010
Location: Alabama
Posts: 7,417
Default Re: Coil failure ?

Check the coil for carbon tracks . Carbon tracks will short out the coil if they make it to the metal part of the coil . If a carbon track is found , it usually can be scraped off with a pocket knife and all should be well .
Purdy Swoft is offline   Reply With Quote
Old 08-19-2019, 07:28 PM   #6
Fairview
Member
 
Join Date: Dec 2010
Location: Waynesboro, Virginia
Posts: 49
Default Re: Coil failure ?

I have recently had a coil failure such as you describe. My Model A would run fine for 10 minutes or so, then it would start missing and barely run. Once it cooled down completely, it would run again for about 10 minutes.

After replacing the coil, I am back in business.
Fairview is offline   Reply With Quote
Old 08-19-2019, 08:13 PM   #7
Mulletwagon
Senior Member
 
Mulletwagon's Avatar
 
Join Date: Jan 2019
Location: Florida Panhandle
Posts: 205
Default Re: Coil failure ?

Might check the resistance in the primary and secondary windings. Seems like the secondary winding may be the issue. Unless there is a hard failure, coil troubleshooting can be challenging. The number of coils changed is much more than the number of actual failed coils. Let us know what you discover.
Mulletwagon is offline   Reply With Quote
Old 08-19-2019, 08:19 PM   #8
40 Deluxe
Senior Member
 
Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,024
Default Re: Coil failure ?

Quote:
Originally Posted by Ed in Maine View Post
Maybe the cutout opened up disconnecting the generator from the battery, the generator voltage goes high because it is not regulated by the battery and the excessive voltage overheats the coil and damages the coil windings. Ed
1. If the cutout opens, how does generator voltage get to the coil? 2. Isn't generator voltage regulated by the position of the third brush, not the battery?

Last edited by 40 Deluxe; 08-19-2019 at 08:34 PM.
40 Deluxe is offline   Reply With Quote
Old 08-19-2019, 08:46 PM   #9
Purdy Swoft
Senior Member
 
Purdy Swoft's Avatar
 
Join Date: May 2010
Location: Alabama
Posts: 7,417
Default Re: Coil failure ?

Voltage depends on the volt of the battery that is used . the generator charges in amps and the amount of amps that the generator charges is controlled by the adjustable third brush in the generator . To increase the amount that the generator charges push down on the third brush . to decrease charge , raise the third brush .
Purdy Swoft is offline   Reply With Quote
Old 08-19-2019, 09:01 PM   #10
B0B
Member
 
Join Date: Jun 2010
Posts: 82
Smile Re: Coil failure ?

The condenser would be the first suspect on my list Those original style condensers are real cheaply made inside take one apart. After taking one apart and seeing how the connections are made and what they are made of I am using only the more expensive short proof condensers . B0B
B0B is offline   Reply With Quote
Old 08-19-2019, 09:03 PM   #11
Dick Steinkamp
Senior Member
 
Dick Steinkamp's Avatar
 
Join Date: Apr 2016
Location: Bellingham, WA
Posts: 1,158
Default Re: Coil failure ?

Quote:
Originally Posted by Mulletwagon View Post
The number of coils changed is much more than the number of actual failed coils.
X2. If I had the condenser and coil biz for Model A owners who changed those parts when they were good, I'd be a rich man.
__________________
All steel from pedal to wheel
Dick Steinkamp is online now   Reply With Quote
Old 08-19-2019, 10:40 PM   #12
dansluck
Member
 
Join Date: Dec 2014
Location: Nevada
Posts: 80
Send a message via AIM to dansluck Send a message via Yahoo to dansluck
Default Re: Coil failure ?

Mine failed on a rural road in Nevada, 50 miles from nearest house. I let it cool turned it over and drove home. Bought a new coil and have been carrying it around in the car for 2 years but the old one is still working. Old coils are oil cooled and sometimes short-out when pointing down. Good luck
dansluck is offline   Reply With Quote
Old 08-20-2019, 08:12 AM   #13
1928Mik
Senior Member
 
1928Mik's Avatar
 
Join Date: Feb 2017
Location: Zanesville Ohio USA
Posts: 138
Default Re: Coil failure ?

I've had coil failure in cars, but it's rare. My A was running great this summer but started missing and would barely run. Stalled in the driveway so I pushed it in the garage since it would not start again. Swapped the coil out but still nothing. It had a "made in USA" condenser that I had swapped out two years ago from my Dad's stash, so I didn't think it was the culprit, but changed it with a short-proof one from Snyders and engine started right up.
__________________
1928 Niagara Blue Phaeton
1972 Olds 442 Convertible
1928Mik is offline   Reply With Quote
Old 08-20-2019, 08:40 AM   #14
ryanheacox
Senior Member
 
ryanheacox's Avatar
 
Join Date: Apr 2013
Location: Northwest CT
Posts: 615
Default Re: Coil failure ?

Did you replace the condenser for a reason? I would look at the work you did recently before changing out a part that has been trouble free for 50 years. Those old coils are known to be very reliable.



On a side note, I recently acquired 2 untested original coils. Put them both on the car, both made a nice strong blue spark. Gave one a coat of paint, put it on the car and I swear it runs better than the 30 year old oil filled coil it replaced.
ryanheacox is offline   Reply With Quote
Old 08-20-2019, 09:55 AM   #15
katy
Senior Member
 
katy's Avatar
 
Join Date: Jun 2015
Location: Alberta, Canada
Posts: 2,095
Default Re: Coil failure ?

Quote:
The condenser would be the first suspect on my list
Ditto
__________________
Don't go away mad, just go away.
katy is offline   Reply With Quote
Old 08-20-2019, 10:46 AM   #16
duke36
Senior Member
 
Join Date: Jun 2015
Posts: 1,063
Default Re: Coil failure ?

Quote:
Originally Posted by dansluck View Post
Mine failed on a rural road in Nevada, 50 miles from nearest house. I let it cool turned it over and drove home. Bought a new coil and have been carrying it around in the car for 2 years but the old one is still working. Old coils are oil cooled and sometimes short-out when pointing down. Good luck
Modern replacements are oil or epoxy type material filled. The oil types often can be shaken to hear sloshing , and the windings may not get completely covered. . Supposedly Ford developed a molten asphalt based insulating fluid called Hydrolene that would solidify into a paste that was used in some later Model T coils and could have been continued on in later years' coils. Some owners like to install the modern oil types with the terminals up for better coverage.
Same experience as in post 14.
duke36 is offline   Reply With Quote
Old 08-20-2019, 11:00 AM   #17
George Miller
Senior Member
 
George Miller's Avatar
 
Join Date: May 2010
Location: NC
Posts: 2,953
Default Re: Coil failure ?

My vote is condenser. or a loose conection.
George Miller is offline   Reply With Quote
Old 08-20-2019, 11:25 AM   #18
rocket1
Senior Member
 
Join Date: Mar 2014
Location: Midland Park,N.J.
Posts: 823
Default Re: Coil failure ?

I purchased a NOS Delco coil for my 50 olds it quit on me after a short while,when the engine rpm went up the engine would start to die,then it left me on the side of the road.The condensers are all original style for the most part,Brattons sells an excellent one.
rocket1 is offline   Reply With Quote
Old 08-21-2019, 08:52 PM   #19
Conaway2
Member
 
Conaway2's Avatar
 
Join Date: Apr 2019
Posts: 77
Default Re: Coil failure ?

Update - new coil and condenser installed today, although both removed parts tested OK with my DVM. I have good spark now, and the timing is right on the mark, but the car will still not start. I’m puzzled, as there is plenty of fuel flow to the carburetor. tomorrow, I plan to take the carb off and check it out. The car died suddenly after I had just filled the gas tank to the top and was driving home at 40 mph or so. I would appreciate any bright ideas, as I am puzzled !
Conaway2 is offline   Reply With Quote
Old 08-21-2019, 08:56 PM   #20
ryanheacox
Senior Member
 
ryanheacox's Avatar
 
Join Date: Apr 2013
Location: Northwest CT
Posts: 615
Default Re: Coil failure ?

Sudden death would usually turn me towards the ignition system. However, gas flow to the carb doesn’t always equate to gas flow out of the carb. Crank it and see if the plugs get wet?
ryanheacox is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:46 PM.