Car died, No spark!

[Wood and Steel]

Alright everyone, I'm having trouble figuring this one out. I was taking my '51 up to my parents house for Christmas and it died on me a couple of miles out of town. For some reason, I lost spark.

 

I will have to give an abridged report of trouble shooting, as I'm typing this on my phone around family:

 

I've got 6v at the coil and the dis. I've check resistance on the coil and got something around 1.5 and 8k. The cap and rotar look clean. The points I did a couple years ago, and still look good. They were sparking more than the internet told me they should, so I changed the condenser. I changed the wires coming off the coil a few months ago. I get spark with the plug directly connected to the coil, but not with the coil to the distributor, and I can't figure out why.

 

Additional facts that may or may not help: it was a foggy, rainy night. It was about 40*. I have no experience with ignition systems pre 2000. I don't have access to my shop manual, and the only video I've had a chance to watch is from Keith. I've had the car for about 6 years. It's a 56 flathead with a 53 OD. Mostly original wiring harness, but I just did the battery cables this summer (00).

 

Sorry I don't have time to give a more detailed account, but I'll answer any questions to the best of my ability. 

[Sniper]

Look at the inside of the cap, in the center should be a carbon button that makes contact with the tab on the rotor.  Is it still there? 

 

That is usually the culprit in this specific instance.

[maok]

It appears to be related to the distributor wiring or condensor.

 

Do you get spark from any spark plug wires?

[Wood and Steel]

6 minutes ago, Sniper said:

Look at the inside of the cap, in the center should be a carbon button that makes contact with the tab on the rotor.  Is it still there? 

 

That is usually the culprit in this specific instance.

 

 

The cap looks new still. Button is intact.

[Wood and Steel]

6 minutes ago, maok said:

It appears to be related to the distributor wiring or condensor.

 

Do you get spark from any spark plug wires?

 

I get spark with wire one if I plug it directly into the coil, and that's the one I'm using for testing. I checked all the wiring I could think to check with the multi meter, and got what I expected. No shorts, good voltage. I definitely could have missed something though. None of the wiring has been changed for several months, and the car is used as a daily driver. 

[Sniper]

Then check your coil wire to see if it is good.

[maok]

47 minutes ago, Wood and Steel said:

 

I get spark with wire one if I plug it directly into the coil, and that's the one I'm using for testing. I checked all the wiring I could think to check with the multi meter, and got what I expected. No shorts, good voltage. I definitely could have missed something though. None of the wiring has been changed for several months, and the car is used as a daily driver. 

 

So spark from the coil but not from the distributor?

 

Check the condensor for a short.

Edited December 27, 2023 by maok

[Wood and Steel]

49 minutes ago, maok said:

 

So spark from the coil but not from the distributor?

 

Check the condensor for a short.

 

That is correct. I already changed the condenser. I assume that would take care of any short.

 

To answer Sniper (sorry, i cant figure out how to double quote on the phone: I already suspected that. I just happened to have all the stuff to make new wires in the car (I was planning on doing some major maintenance while I was up anyway). Made a new one, no luck.

[Dave72dt]

you're getting a spark through a wire plugged into the coil.  That means the points, condenser and coil are working after a fashion at least.  Multiple sparks from that wire while the engine is turning over is good.   A wet cap, carbon tracking in the cap or a bad or incorrect rotor would be the next.  Continuity from the coil wire to the button inside the cap can be checked.  That's good, all that's left is the rotor which can short through to the rotor shaft.

[Митя]

You also need to check the contact in the distributor. It may be closed all the time or open all the time. You need to turn the engine with the distributor cap removed and see if the position of the contact changes. Sometimes the stop that runs along the polyhedron gets erased.

Edited December 27, 2023 by Митя

[Wood and Steel]

39 minutes ago, Dave72dt said:

 Continuity from the coil wire to the button inside the cap can be checked.  That's good, all that's left is the rotor which can short through to the rotor shaft.

 

I wouldn't have thought to check for a rotor short. The cap looks dry and free of carbon, assuming that's what carbon traking is. 

[Wood and Steel]

33 minutes ago, Митя said:

You also need to check the contact in the distributor. It may be closed all the time or open all the time. You need to turn the engine with the distributor cap removed and see if the position of the contact changes. Sometimes the stop that runs along the polyhedron gets erased.

 

The points seem to be opening and closing properly. There was too much spark when I first checked it, so I changed the condensor. It has a small bright spark every rotation now.

 

I set the points and checked dwell not too long ago, and don't have the tools to double check with me, but I don't think that's the issue.

[Митя]

Have you checked the spark plug and wire? You need to unscrew the spark plug, put on the wire that goes to the cylinder, and place the spark plug on the engine body. You need to try to start the engine.

[Wood and Steel]

6 hours ago, Митя said:

Have you checked the spark plug and wire? You need to unscrew the spark plug, put on the wire that goes to the cylinder, and place the spark plug on the engine body. You need to try to start the engine.

 

I have indeed tried that. That's how I know I'm getting spark plugged directly into the coil, but not plugged into the distributor. 

[oldodge41]

My 2 cents. I am suspecting the distributor cap or rotor based on your explanation (more so the cap). They may look fine, but somewhere I suspect your spark from the coil is getting diverted to ground. Moisture can cause that. Not typically seen shutting down a running engine, but one that is hot, shut off and sits a while then will have moisture problems in the cap in the weather you describe. I would pull the cap and rotor, spray down with wd-40 or another ignition drying product or electrical cleaner, wipe dry and try again. If the same result, spark from coil, at the proper interval but no spark at plugs, I would replace the cap and rotor. 

 

Disclaimer: I am not a mechanic, I did not stay at a Holiday Inn Express last night, but I have been working on old cars for a long time. I'm a hack, but I sometimes get lucky and fix things.

 

Good luck and please keep us posted on your progress.

[Plymouthy Adams]

in other arenas of the car hobby there have been multiple failures of rotor buttons...cheaply made with little and often defective molded parts that would allow the spark to short to the distributor shaft thus the dead ignition spark

[Wood and Steel]

11 hours ago, Dave72dt said:

All that's left is the rotor which can short through to the rotor shaft.

 

I think we have a winner! It seems the rotor is shorting through the shaft. I think I have a spare rotor at home, so I'll update tonight or tomorrow after I get a chance to test it.

 

Thanks!

[Митя]

In many years I have not encountered such a malfunction. A slider with a resistor was used for a very long time; such a circuit helped to avoid interference in the radio receiver. The resistor broke and there was no spark.

I always do the following: I measure the voltage on the ignition coil (when the contact of the ignition distributor is open, there is voltage on both contacts of the coil. If the contact is closed, then there is no voltage on the contact that goes to the ignition distributor.) What you are talking about is unlikely, because that the design does not allow this to be done. Check the contact group in the ignition distributor. I'm guessing that's the problem.

If everything works, then this is very good. If not, then measure the voltage at the contact itself.

 

I'm wondering what is causing the problem. Maybe you can attach a photo?

Edited December 27, 2023 by Митя

[nonstop]

If the rotor is not the problem, don’t discount a bad condenser right out of the box.  The failure rate is ridiculous.  Have had way too many go bad.  My latest was my 1940 Chrysler just 2 weeks ago.  Ran briefly then died.  Did this a few times and long story short - was the condenser, with MAYBE a couple hundred miles.  This was from Napa, but had same luck with Oreilly and others as well.

[48ply1stcar]

Have you replaced the coil. I've spent way to much time chasing problems when it's the coil. Don't forget you get 6 volts with 4 D size batteries. It's the AMPS man.

[Wood and Steel]

I had to wait for parts to come in, but it was officially the rotor shorting to the shaft. I couldn't visually see anything wrong with it, but it fired right up once I switched them out. I'm not sure I would have ever thought to check that without the help of this forum, so thanks yet again! This is the first time the car has stranded me, but I definitely learned a lot about the ignition system because of it.

[Hamilton]

5 hours ago, Wood and Steel said:

I had to wait for parts to come in, but it was officially the rotor shorting to the shaft. I couldn't visually see anything wrong with it, but it fired right up once I switched them out. I'm not sure I would have ever thought to check that without the help of this forum, so thanks yet again! This is the first time the car has stranded me, but I definitely learned a lot about the ignition system because of it.

Oh, I think you'd have figured it out.  Well, you might not have figured out the actual issue, but you'd have eventually solved it by changing out the cap and rotor which, even if you didn't realize it at the time, you'd pretty much narrowed it down to.