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Old 12-12-2020, 11:30 PM   #1
DNLs1930
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Default Coil or condenser over heat

First on the road failure...



Out for a drive today and about 15 miles in (some traffic) the car lost power sputter a little and then the engine shut off. I tinkered with the GAV because I thought maybe it was the issue (never changed the setting from start) and after we were parked a few minutes the car restarted and ran for about 2 miles or so and died again. Dropped the clutch and refired with a very (not) nice loud backfire ran for a little while and then died for good. pulled over near a conveniently located parts store and started looking at the spark.



VERY WEAK spark and then no spark... Coil was my first guess.



NO 6v coil in stock... Time for a tow? Almost; car sat for about 20 min and fired right up at which time I turned tail for home which was about 20 miles away.



Made it through town and out on the service roads about 10 miles and poof dead... called for a tow assist from a friend and while we waited the car started a few times and we beet feet towards home but came up short by about 5 miles.



Tow went well and upon arrival at the house the car started right up and I pulled in the garage with no more issues.



SO

Coil or condenser? Still think it is the coil.



Is this a classic example of a coil or condenser failure? Or both?



I had a spare condenser and points and have a few (rookie) questions about those I will address later.



Appreciate all the help and knowledge (in advance)
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Old 12-13-2020, 08:05 AM   #2
Patrick L.
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Default Re: Coil or condenser over heat

Could be either. Try checking them for capacity.
Check condenser for an open when hot, same with coil.
So if your still using 6v then you need a 1.5 ohm coil. Condenser capacity should be in the 1.7-1.9 microfarad range. Neither coil or condenser should show open at any time.

Plus I think I'd check the whole primary circuit while you're at it just for peace of mind.
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Old 12-13-2020, 10:07 AM   #3
rotorwrench
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Default Re: Coil or condenser over heat

Testing a capacitor or an ignition coil without the proper equipment is not going to tell a person the whole story. Coils have to go through a warm up before a test is conducted. All it takes is a broken strand in the primary coil that will function when cool but then malfunctions after it expands with heat and opens the crack further.

Changing the condenser with a part known to be functional is the best first test. If the condition persists, replace the coil with a known functional unit.
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Old 12-13-2020, 10:16 AM   #4
Bob Bidonde
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Default Re: Coil or condenser over heat

The symptoms you note are more indicative of a condenser going bad. Often a condenser will work when it cools off, but fail again as gets hot. Coils fail slowly, and as the spark weakens, the engine looses power. The easy fix is to change the condenser. You should also look at the points, as they may be pitted or frosted.
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Old 12-13-2020, 10:58 AM   #5
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Default Re: Coil or condenser over heat

Should carry a spare coil and condenser in the car (as you stated?). Also review other threads about coil and condenser type and quality. Many new oil filled coils are not reliable and may need the terminals mounted up for proper internal cooling. Also check fuel filter and/or look into tank for crud buildup.
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Old 12-13-2020, 12:16 PM   #6
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Default Re: Coil or condenser over heat

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In my brief Model A experience (1,800 miles) I had the same symptoms and didn't recognize them. I got stranded 30 miles from home and shelled out for a tow and several hours of modern mechanic time to find it was the condenser.

I immediately started carrying a spare condenser. Having heard how unreliable they are, and because my car came with a manifold heater which I've read can accelerate condenser failure from heat, I now carry two, plus the hand tools to change it out. They're small and cheap. I have a spare coil too, but so far I don't keep it in the car.

I've also had fuel issues from ethanol gook. So now I keep the fuel clean, add stabilizer over the winter storage, keep a log of when the car last ran and was stabilized, keep the points clean (220 sandpaper) and gapped. My start reliability has gone up and cranking time has gone down as a result.
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Old 12-13-2020, 12:31 PM   #7
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Default Re: Coil or condenser over heat

In addition ot all the above ...check the condenser well grounded. ( "earthed " over here!)
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Old 12-13-2020, 12:49 PM   #8
Kevin in NJ
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Default Re: Coil or condenser over heat

Use to always check condensers and keep a pile in the car.

The burn out proof ones seem to work. The one in my brothers car is like 20-30 years old.

We have a coil condenser tester that makes the spark arc. Always fun to play with and start fires in paper, but I digress. Coils often with work great cold and fizzel out when warm. Same for the condensers.

Points on the other hand, so long as the contacts are not burning away and there is a wear block then they are fine.

DO NOT REPLACE points unless there is something clearly wrong with them. A quality set of used points with a good properly lubricated cam should last you decades unless you are driving thousands of miles. Change points yearly is a waste of money and only increases the level of work. New points have to wear into the cam so they will need frequent adjusting. Once worn in they go long times between needing adjustment.

Do not forget, the upper dist bushing is oiled when you fill up the filler to the top as per the owners manual.
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Old 12-13-2020, 01:10 PM   #9
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Default Re: Coil or condenser over heat

Quote:
Originally Posted by Kevin in NJ View Post
Do not forget, the upper dist bushing is oiled when you fill up the filler to the top as per the owners manual.
You're talking about the pull out brass oiler on the distributor shaft? I thought I read several drops. What do you mean "to the top"?
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Old 12-13-2020, 01:17 PM   #10
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Default Re: Coil or condenser over heat

I had a similar problem with my 56 Chevy. Engine would run fine for a couple of miles then quit. Finally got home and upon looking for the problem I removed the coil resistor from the dash. Upon investigation I noticed that the resistor wire had a slight break and would separate when heated. Replaced resistor and no more engine failure. Interesting side note is that the resistor was mounted on the fire wall facing in so you could not see the wire until removal from the fire wall. Oh well another lesson learned! 👍 😊
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Old 12-13-2020, 01:30 PM   #11
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Default Re: Coil or condenser over heat

Whenever I see these kind of questions I always wonder why our cars are continuously having these problems. I mean, I can only assume we buy our parts from the same sources but I don't have these problems. These cars didn't have these problems when new(er).

Quote:
Originally Posted by Kevin in NJ View Post

Points on the other hand, so long as the contacts are not burning away and there is a wear block then they are fine.

DO NOT REPLACE points unless there is something clearly wrong with them. A quality set of used points with a good properly lubricated cam should last you decades unless you are driving thousands of miles. Change points yearly is a waste of money and only increases the level of work. New points have to wear into the cam so they will need frequent adjusting. Once worn in they go long times between needing adjustment.

Do not forget, the upper dist bushing is oiled when you fill up the filler to the top as per the owners manual.
I agree with Kevin. I never understood why when you give a car a "tune up" you automatically throw a good set of points and condenser away?? I have witnessed "mechanics" not even inspect the parts before installing a complete "tune up" kit.
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Last edited by Ruth; 12-13-2020 at 01:39 PM.
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Old 12-13-2020, 02:42 PM   #12
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Default Re: Coil or condenser over heat

I had a similar experience on a club day trip around the Charleston, SC area. It was a hot day, with a lot of stop and go driving. My car sputtered a bit after an hour of driving, then died completely as we pulled into our lunch stop. After lunch, the car started right up and I drove 15 miles home with no issue.

I had recently changed the condenser and installed a new modern replacement 6V coil, thinking that the original 90-year old coil was a reliability risk. The replacement coil is oil-filled and mounted upside down, as the original was. I have read and been told that oil filled coils should not be run upside down.

So I;ve now replaced the oil-filled coil with an epoxy-filled Pertronix Flamethrower coil and have had no further issues. However, I carry the original coil with me as a spare now.

Jim
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Old 12-13-2020, 03:11 PM   #13
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Default Re: Coil or condenser over heat

My continuous issue....THE CONDENSER!!!. Same symptoms as you and it has always turned out to be the condenser failing. If you read through many threads, hobbyists go through several before they get a good OEM type condenser. I have had them last about 120 miles, tops, even if they are "short proof". My spring 2021 project (minor one) is to change to the modern points system (top and lower plate). My A friend who has done this says he has not had a problem since he converted to the modern system.
I had a 1951 Plymouth. When I tuned it up I always purchased; points rotor, condenser, distributor cap. After a while I had a pile of condensers and never knew of any problems with the plymouth ignition system. Why? The condenser was far from the heat of the engine and exhaust manifold.
I am not going to to tour with 3 condensers in my tool box. I have been lucky so far and I was not out in the middle of no where, hearing banjos in the distance, and raining when I had a condenser failure. But a condenser failure makes my wife feel uneasy with the bang, sputter, backfire. I gave the OEM, Henry design, a try, but I am upgrading and parts are on order.
I just want to sit back and "enjoy the ride". I am planning on going to NH in the spring for 2021 for the MAFCA tour. I do not want the hood up too often.
I will let everyone know how I make out with the upgrade.
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Old 12-13-2020, 04:37 PM   #14
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Default Re: Coil or condenser over heat

Here are two ideas I copied from other posts:

Here is something that is easy to try. Connect a second condenser from the passenger side of the coil to ground. Easy with jumpers. (In other words-mount a condenser on the firewall and when the car stalls just jump the condenser wire to the passenger side of the coil...like changing the condenser).

Below is a copy of a longer post but on how to test coil:

You should have voltage on both sides of the coil. If not,
remove the red wire on the coil and check again. If you now have voltage on both sides, you have a problem further on. If the voltage is still only in one side you have a bad coil.

Last edited by jg61hawk; 12-13-2020 at 04:44 PM.
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Old 12-13-2020, 05:41 PM   #15
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Default Re: Coil or condenser over heat

Quote:
Originally Posted by ArtimusGordon View Post
I had a similar problem with my 56 Chevy. Engine would run fine for a couple of miles then quit. Finally got home and upon looking for the problem I removed the coil resistor from the dash. Upon investigation I noticed that the resistor wire had a slight break and would separate when heated. Replaced resistor and no more engine failure. Interesting side note is that the resistor was mounted on the fire wall facing in so you could not see the wire until removal from the fire wall. Oh well another lesson learned! 👍 😊



I ran into a similar issue during a Plymouth Trouble Shooting contest in the 60s. The Chrysler boys sawed thru the primary lead very sneakily. I think it took me 17 seconds longer to find it than the first place guy.
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Old 12-14-2020, 08:51 AM   #16
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Default Re: Coil or condenser over heat

I used to have this problem with my first "A". Like most others, it turned out to be the condenser. I carry a gallon of water with me in case of an over-heat, which I never have, but I found that if the car stalled I would just take a rag and soak it with water and use it to cool down the condenser and away we'd go. A quick fix for alongside the road repair.


I changed to the modern style distributor plate from Mike's Affordable Model A parts and have not had the problem since.
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Old 12-14-2020, 12:45 PM   #17
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Default Re: Coil or condenser over heat

Quote:
Originally Posted by jg61hawk View Post
Here are two ideas I copied from other posts:

Here is something that is easy to try. Connect a second condenser from the passenger side of the coil to ground. Easy with jumpers. (In other words-mount a condenser on the firewall and when the car stalls just jump the condenser wire to the passenger side of the coil...like changing the condenser).
I have never tried this so I am asking for my own future info. Would the "bad" condenser that is still in the circuit have any effect in the running of the car after the "spare" condenser is connected? Seems to me it would, especially if it was shorted out??

BTW, I have not changed my condenser in ~7 years now. And only then because I thought I had a bad condenser, which I did not.
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Old 12-14-2020, 12:49 PM   #18
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Default Re: Coil or condenser over heat

Does anyone use one of those heat shields that the vendors sell? https://www.snydersantiqueauto.com/P...earchByKeyword

I had one on my car but the way it attached under the head nuts concerned me. Maybe with some washers it would be OK.
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Old 12-14-2020, 02:34 PM   #19
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Default Re: Coil or condenser over heat

i tried one of the heat shields and wasn't that much impressed . Needing to loosen two head nuts to install the shield didn't seem to be the best idea . Loosening head nuts runs the risk of losing the seal between the head gasket and the water jacket . The distributor can't be removed without first removing the shield . Even if the coolant is drained first will still run the risk of coolant entering the oil pan . If the seal is broken between the gasket and the water jacket , there is NO guarantee that retightening the head nuts will reseal the gasket .
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Old 12-14-2020, 02:39 PM   #20
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Default Re: Coil or condenser over heat

DNLs1930,

Had the same problem. Car started acting up just like yours. Since I was new to Model A's, I went trough the usual checks without any success until replacing the coil. The PO had an oil filled coil mounted upside down like the normal position for A's. What I believe was happening was the coil was overheating from lack of oil to cool it in it's upside down position. I think that some coils just don't have enough oil inside to properly cool them down when mounted upside down. Replaced the coil with an epoxy filled Pertronix that lasted about 300 miles before shorting out. Replaced it with another Pertronix hoping that the first one was just a defect. I still carry the old oil fill coil as a back up. I wire it right side up and it seems to work okay.
One other thing that may have contributed to my coil problems. My distributor body gap to rotor was in excess of .045 on cylinder #1 and there were visible cracks in the body. This is how the car was setup from the PO. I decided to replaced and modify a new distributor body to give me an even gap of .025 between the body and rotor. I don't know if that made any difference since only time will tell.

Ruth,
My engine has that shield on it from the PO. Can't really tell if it is doing any good with the exception that I have not yet changed the condenser. My points and condenser are the original set up.

Tom L.
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