I’m wondering if my coil is going bad
 

I bought my 1931 Victoria a little over a year ago. It has always started extremely well, usually with one touch of the starter button. As I learn more about Model As, I’ve been replacing worn parts, ordering spare parts, and sometimes swapping out known good parts that came with the car so that I would serviceable parts for spares.

About six weeks or so ago, I swapped out the condenser for a new one. The engine continued to start and run fine.

About two weeks ago, I swapped out the Ford script coil for an oil filled coil that the previous owner sold me with some other spare parts. At the time of car and spare parts sale, I didn’t know that a coil could could be tar filled, expiry filled, or oil filled. I mounted the oil filled coil upside down like the original, and, presumably, there is an air bubble at the top of the coil on its inside. The wiring would not reach far enough to mount the coil right side up.

I’ve driven the car about 300 miles or so, and, yesterday, I noticed the car was hard to start after the engine got warm. I also noticed the coil got pretty warm to the touch. I could still place my hand on it without getting burned, but it seemed pretty hot to me. It was about 72 degrees outside on a nice fall day. The engine has a thermostat that keeps the coolant around 170 degrees.

How warm should a coil get? (I didn’t have my temperature gun with me to check it.)

Does it sound like this “new to me” coil is failing?


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Re: I’m wondering if my coil is going bad
 

Put the old coil back on and try it

Re: I’m wondering if my coil is going bad
 

oil filled coils are meant to be run right side up.

Re: I’m wondering if my coil is going bad
 

Re: I’m wondering if my coil is going bad
 

Yep, what Ray said. Or when its warm/hot/acting up, check with the ohm meter.

Re: I’m wondering if my coil is going bad
 

"The wiring would not reach far enough to mount the coil right side up." Get a longer wire........


Paul in CT

Re: I’m wondering if my coil is going bad
 

I agree with Paul .

I’m wondering if my coil is going bad
 

That would be wireS. Nothing (the coil wire nor the wires for the coil terminals) would reach. ;-)

I’m not firmly convinced I have a coil problem yet, which is why I posted. I don’t want to keep changing a bunch of stuff quite yet. I’ll probably put the old coil back on after some more road time.

I was hoping to get some feedback about how a coil acts when it is potentially beginning to fail.

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Re: I’m wondering if my coil is going bad
 

If you decide to get a new coil, try the Pertronix 6 volt, epoxy filled "Flame Thrower" coil. Got mine from Summit Racing, very happy with it too! The part # for that particular coil is:40111. It is the 1.5 Ohm coil for the Model A if you still run 6 volts. They do make one similar for ones that changed over to 12 V.

Re: I’m wondering if my coil is going bad
 

Have you tested the readings across the terminals ? Different values (with or without internal or external resistors) for 12 volt vs. 6 volt

Re: I’m wondering if my coil is going bad
 

I've had 2 of those coils fail on me in short time. Not a good option, IMO.
I run any old oil filled coil now but mounted with terminals up. As has been said, you would need to get a longer HT lead but I've had no trouble since.

Re: I’m wondering if my coil is going bad
 

My Pertronix flame thrower coil is still holding up good after 14 years on my roadster . I run the part number 40611 epoxy 3.0 ohm version on 12 volts . I get instant starts ann more power that can be felt . The six volt version may not perform the same as the 12 volt version .

Re: I’m wondering if my coil is going bad
 

[QUOTE=shew01;1950614]That would be wireS. Nothing (the coil wire nor the wires for the coil terminals) would reach. ;-)

I’m not firmly convinced I have a coil problem yet, which is why I posted. I don’t want to keep changing a bunch of stuff quite yet. I’ll probably put the old coil back on after some more road time.

I was hoping to get some feedback about how a coil acts when it is potentially beginning to fail.

That indeed would be good feedback to have.

Re: I’m wondering if my coil is going bad
 

When failing coil happened to me I felt a definite lack of power. The coil was hot to the touch and eventually I noticed that it got quite hot to the touch, burn fingers hot , and the oil began to leak out of it. Barely got the car home from a three block run that time. Another instance I had a foam fillled A(EApoxy) that I thought had an internal resistor. It did not and it also failed to last for a short drive of about three miles before there was a decided lack of power and a few miss fires. Next morning the car was cold and started right up and I took off for half a block. It quit running and the coil blew a plug out of the bottom of it (opposite end from the ht lead) and all the epoxy foam came out and ran down my fire wall. That one was my fault for not installing a resistor. They definitely will loose power as they heat and usually will work okay for a minute or two until they overheat. Just enough to get you a good walk from home when the car will die. If the coil is oil filled you can shake it by your ear and even I can hear the fluid sloshing around inside. If so mount it with the HT lead up and use longer wires to make it function. I'm told not all oil filled will fail, but most will. Originals were filled full with a tar like substance and don't mind being HT lead down.

Re: I’m wondering if my coil is going bad
 

Have you checked your point gap ? Maybe they are wearing ? Just a thought and easy to check!!!

Re: I’m wondering if my coil is going bad
 

I have one more spare coil. It’s an oil filled one that I bought new from a Model A vendor before I learned the differences between coils. I plan to try it out too when I get a chance. I still have the oil filled coil (that I originally posted about) in the car at the moment.

Yesterday, the car was hard to start twice (on two legs of a trip) after it was driven 10 miles or so for each leg of the trip. So, the engine was hot when it didn’t want to start. However, it started fine at the end of our trip in our garage with the engine hot.

This evening, the car was hard to start cold.


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I’m wondering if my coil is going bad
 

No, I have not. Can this be tested with the coil in place on the firewall? If so, do I need to disconnect the wires on the terminals? Or, can I leave those in place?


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I’m wondering if my coil is going bad
 

My oil filled coil is definitely getting warm, but I don’t know if it’s “out of spec” (for lack of a better phrase) from a temperature perspective.

So far, I have not noticed a lack of power.

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I’m wondering if my coil is going bad
 

I reset the point gap about a week ago. I’ve driven the car about 300 miles since then without an issue (until I swapped out the coil later).

So, there is a correlation with hard starts after swapping out the coil. But, that doesn’t necessarily mean that the coil is the culprit.


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I’m wondering if my coil is going bad
 

Were your leads to the coil terminals long enough to reach the terminals with the coil installed right-side-up? Or, did you have to add some wire to lengthen them?

There is no apparent way for me to stretch my wires to reach the coil terminals if I turn the coil right-side-up.


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