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I went to start my ’41 Model 43 today, turns over great, has gas, but seems to have a very weak spark and won’t start.
Checked voltage at ignition switch and it was around 4 volts (on a 6 volt system).
That doesn’t seem right to me, is it due to the current limiter in system?
Car won’t start, by the way….any suggestions?
David,
You have a ’31. If you had a ’41, it would be a miracle!
4 volts is low. Try checking grounds first, assuming the battery is fine. Then check the point gaps and point face condition. You may want to try some contact cleaner.
Got to get the boys to baseball, will try to call you later.
Bob
Hi David, you might have a poor ground [+] connection to the body, but have a good connection to the engine and starter motor, this is quite possible if you have an independant ground from the battery directly to the starter.
To get the car started, use a jumper wire and go directly from the battery [-] post to the switched side of the coil, or coils. this circumvents the body’s wiring and will get battery voltage to the coil. Just don’t hook the jumper wire to the coil post/connection that goes to the points !! if you do, you will let all the smoke out of the wires and points !!
The current limiter should not be in the ignition circuit. Check for loose connections on both studs on the back of the ammeter first, these tend to shake and come loose.
Check your voltmeter on the battery, it should read 6.1-6.3V. Sometimes the 9v battery inside the VOM will be weak and give false voltage readings..
Another common problem with starting: The choke does not close fully on the UU-2 and UUR-2 carburetors, especially as they tend to warp out of round with age and pot-metal movement. Check to be sure the butterfly of the choke is closing completely, or you won’t get a good choke-action, and it is a bear to start.
Greg Long
Thanks, of course it is a ’31.
Voltage at battery good. Did the jump directly to coil. Gas in carb. Spark at distributor. Even put a few drops of gas in 4 cylinders and tried to start. Still did not run.
We loaded it up and took it to a friend’s shop who specializes in early cars. My ’37 Cord phaeton was already there, so at least I know where to go to visit some of my collection!
It’ll be interesting to see what he finds, has to be something simple, but I worked on it for hours and couldn’t get it to run. That car has never done that to me, it’s been a reliable ride for over 30 years.
Thanks for all the suggestions….
I watch this with all interest as I have a 1929 doing the same thing. But I don’t have a friend with a shop for early cars. “Early”” around here means after 1970 !”
A bad battery will often read OK with today’s modern testers and chargers. If a car runs well when parked and won’t start it’s highly unlikely that a cool or condenser went pad while sitting. Corrosion, almost anywhere in the system is a possibility as is a bad battery. Keep it simple…….you will find it.
David, let us no the diagnosis-this one is very interesting.
John
Two of my old car buddies immediately said “corrosion”…..we’ll see. It’s a very slow paced old car shop so it might take a little time to find out what he runs into, but will update when I know.
Thanks dc
OK, to end this story, so to speak….the condenser on my car failed. At some point, the points burned. So, while I was able to get 6 volts to distributor, the spark was next to nothing.
No explanation for the low voltage reading at the switch, after rechecking everything is fine.
The distributor has been put on a distributor test machine and is now set up correctly with new points and condenser.
Car is running great.
Great to hear David, just in time for some Fall touring!
Dave……install a battery cut off switch…….and don’t leave the key on!
A hint for testing for a bad condenser: Remove the coil wire from the distributor cap, hold it near the engine head or block, and crank the engine with the ignition on.
A bad condenser will often give 2-4 good hot blue sparks, then fade to yellow-red short, weak sparks then no spark at all.
I usually do the above test slightly differently: I remove the coil wire from the distributor cap, or if that is difficult like on the ’29 caps with the fragile cover, I’ll use a spare piece of spark plug [ignition] wire plugged into the coil. Then I remove the distributor cap from the distributor, and use a fingernail, or a small screwdriver to repeatedly open/ snap closed the points, This way I can see the spark easier, and it only takes one person. The risk is getting a bit of a shock from the ignition system.
I’ve seen many condensers fail just sitting in hot weather. A condenser is made from multiple layers of thin metal foil, separated by wax paper, the wax paper gets hot enough to let the wax weep out and the insulation value goes away, allowing the foil layers to short circuit.
A condenser MUST have it’s metal exterior grounded to the engine, a loose screw on a condenser can cause a no-start. A test condenser/emergency [get it home] can be made with a condenser with a wire soldered to the mounting tab of the condenser, and an alligator clip on both of the wires on the condenser. Clip the soldered on wire to the engine or chassis, the other end to the point’s wire on the coil or distributor. Usually, even with a failed condenser still hooked up, the emergency condenser will get the engine started.
I’ve also seen a distributor cap and a few rotors develop an internal crack from heat and age. The engine ran great the last time it wad driven into it’s parking space, but won’t start a few weeks later. Thankfully, this is not very common.
Greg Long
Another note on condensers, the fellow working on the car has a nice shop only working on early cars and is a Mopar guy, with cars from 1915 Dodge up in the Mopar category and others such as a 1909 Reo and a 1911 Hudson.
He used to run a NAPA store. He said you can buy the condensers new at NAPA, they still stock ones suitable for use on the older cars, but, he said, buy TWO, because brand new out of the box they can be bad.
Interesting, too, that condensers aren’t rated by voltage.
There are now solid-state condensers, some form of ceramic i think. Condensers are the main item that goes bad in old tube-type and transistor-type electronic equipment.
The space programs and military applications drove the research and development of a more reliable condenser.
My understanding is that a condenser is much like a shock absorber. In our application in point/condenser ignition systems, a wrong capacity condenser will allow the points to pit and transfer metal from one point surface to the other. This shortens the life of the points, but does not cause the ignition system to fail to create spark.
Greg Loftness used to work for Onan, the generator company. He participated in a study of reliability of ignition systems and fuel systems in gasoline engines used in emergency generator applications. The result was that Onan developed a better quality, more reliable condenser for standby generator applications. The study also showed that standby gasoline engines should be run on either aviation fuel or Amoco/Standard Oil, and a few other premium fuels, due to the stability and lack of varnish creation with these high-quality fuels.
Greg Long
David,
In the low voltage class (under 50 volts), the voltage rating is not much of a factor in the construction of the capacitor. Larger capacitors or condensors for motors or air conditioning compressors (which are motors as well) have ratings, but are also fairly tolerant, to a point. Their construction designates them as starting or running capacitors. Statrting capacitors have a much higher charge (Microfarad) rating to boost the charge available at startup. A compressor motor, for instance, requires 6 times the normal running current to start without damaging the motor windings. If you jump to the capacitor banks used to regulate the voltage on the power grid, their voltage rating is much more critical. I have been way too close to a few that have failed from lightning, testing to failure, etc., and have the hearing loss to prove it.
Greg,
The capacitors you are referring to are electrolytic capacitors, which generally have some form of oil or gel in between the layers of foil. These are the only capacitors that have a polarity. The moisture dries out over time and lack of use, so when older units are restored, the electrolytics are replaced. In some cases, the regular disc capacitors fail or lose their tolerance as well. When working in a TV repair shop in the 70’s, we used to buy two of almost anything we needed, as at least 10 percent of all repair parts (tubes, capacitors, transistors, etc.) were DOA out of the box.
It is much like the older incandescent light bulbs. If you wanted them to last, you would buy bulbs rated at 130 volts. You did sacrifice brightness (about 9 percent), but the bulbs lasted a while.
Bob,
You are a veritable fount of interesting technical information.
BRAVO!
Peter
Peter: you DO recall the failed condenser in your Pierce’s ignition system? I would allow 4-6 sparks, each one weaker, until it would fail completely, and no more spark from the coil.
At that time, it was not something I had seen very often. But since then, a more common failed part that is encountered.
When looking at old radio chassis’ and other older electronic items, often the bigger condensers will show ‘sweating’ of wax out of the exterior of the condensers.
I would like to find a small, modern condenser to put inside the old condenser-can from a ’20’s Delco distributor, and have a reliable condenser in my cars. But, that project is way down on ‘the list’.
Greg
Capacitors in old radio chassis that are bad or questionable will show signs of sweating (as Greg mentioned) or they will be swollen.
Any electrolytic capacitors that show these signs should be replaced before you try to power up the unit.
Damage to tubes and other parts can occur if you power on with bad caps.
Greg,
I have a modern 6V coil and condenser mounted and hidden on the passenger compartment side of the firewall and wired through the loom sho that it LOOKs original, but neither the original coil nor the original condenser are connected.
And yes, I do remember, which is why I did the Mike Bortoli wiring job.
Peter
Greg, I was told at Hershey that the Model T vendors sell a small, modern condenser, so check with them. I saw one at Hershey and it was the size of 4 Chiclets put together….