Hey Hamb'rs! I picked up this 1929 coupe from a fellow member last February (hey Corey!) https://www.jalopyjournal.com/forum/threads/1929-av8-coupe.1248154/ And it's been a fun project so far, but for the life of me, I can't get it to keep a charge, or maybe it's more appropriate to say "can't get it to start reliably". If it's sitting in the garage, battery fully charged, it starts up cold just fine. If I take it for any distance enough to warm it up, though, it will barely crank when I go to re-start it. Not running, battery will still read above 12v, ammeter reading ~30. Starter will just not crank. I have to put a jumper battery on, or get a jump from a friend in order for it to go again. When I go to measure voltage at the battery when the car is running, though, I get no reading. Which is very strange. I just went through with a multimeter and got readings off everything, and it otherwise seems normal. Car won't start, and there's 12.5v reading at the battery. Ammeter reads 30a when you hit the lights. With the car running, at the generator ("excited" with the lights on, and at about 2-3k RPM), there's anywhere between 12-40v being thrown from the positive lead at the back. At the rebuilt Tbird voltage regulator, I'm getting 12v+ readings coming off the battery terminal, and readings from the stomp starter solenoid on the firewall. I just polarized the generator from the regulator just in case that was the problem (disconnected Field lead and touched it to the Battery lead on the VR, generating a spark) What else could I be missing? All connections are clean/solid. Battery has new gold-plated terminals, freshly connected, no grease or looseness. I just cleaned the - terminal ground connection to the ch***is, also. The stomp starter solenoid on the firewall definitely feels hot after the car's been running, which could just mean it's a hot start problem? Electrics are definitely not my strong suit. Help me HAMB! Adam
Updated view of the inside of the voltage regulator. Armature - Closed / Field - Open / Battery - Open/Closed. The Battery terminal was HOT to the touch, even without the engine on or generator running. It does look burned up visually, compared to the others, and even if I flicked it shut, it opened back up as soon as I flicked the headlights on... Wondering if that terminal is cooked and I need to replace... A
If you’re using an inexpensive multi meter it sounds like a lot of electronic “noise” is being picked up.
Im so far from a pro with electrons but woulde start by double checking your battery ground, engine ground and body grounds. Remove them and clean both surfaces up. Had to work through a somewhat similar issue last week.
I had essentially the same issue you’re describing. Mine would fire up instantly cold but would crank slowly hot. The battery always read above 12V and would show a full charge quickly if put on a Battery Tender. It turned out the battery wasn’t bad, it was just “old and tired”. A new battery solved the problem instantly.
Check, check and check. Figuring out the ground situation is definitely first. I'll check the connection from the engine block to the frame, as well as seeing if the fuse box/battery connection is compromised. Adding an additional ground isn't a bad idea either. Turns out Autozone had a replacement Duralast voltage regulator in stock, so I'll swap that tomorrow too. Battery is new-ish (but generic Walmart) so swapping the battery is also on the table.
In truth if the battery, starter and cables are good and the connections are good you should be able to fire that car up, drive to town in the daylight, stop for a bit and fire it up and drive it home or even make another stop and fire it up a couple of times without having any sort of charging system hooked up. First Charge that battery and take it out and carry it to someone who has a good battery tester and have it tested. That is called process of elimination and that starts with knowing that the battery is good. Then clean every connecton on both sides hot and ground. Meaning clean every terminal inside and out to shiny bare metal and inspect every connection. Take those clamp on ends off the cable and clean the insides and inspect the copper wire to make sure it isn't corroded . It wouldn't hurt to take the generator off and haul it to a generator shop to have it tested right. Then it might not be a bad idea to pull the starter off and make sure that it is up to snuff too Meaning test don't guess or ***ume. If you ***ume that the battery is good, the starter is good or the generator is good and don't test all of them at the start it is going to give you a longer and harder fight. It appears that you have fairly large battery cables but the further you go with a cable the larger the cable needs to be. One restrictive spot in the system can slow down th whole system.
Absolutely right @Mr48chev Those painted battery terminals were suspect, which is why I've swapped them for new ones. I'm going to hunt down connection and ground faults tomorrow and see what's uncovered. Remove and re-set those starter connections for sure.The fuse box and light switch in the steering column is next. Battery and generator tests following, but hunting faults in the +/- is definitely first. We'll see what the new voltage regulator does too. My philosophy in troubleshooting is going from the cheapest/simplest places first, on to the more expensive/complex.
Another thing I was thinking... Could be a bad starter. Starts when cold. Once it heat soaks the amperage draw sky rockets and the battery doesn't have enough juice to turn it over anymore.
Cleaned all terminals from generator to voltage regulator. Generator is grounded to the voltage regulator/body as well. Cleaned up ground between engine/frame. Cleaned up the starter poles, re-connected the battery lead from the VR to the + pole. The battery terminal on the NEW voltage regulator seems to be heating up in the same way as the previous one. I can smell it getting hot as soon as current is running, and it's hot to the touch. Can't be normal, right? The only other lead off the battery terminal from the voltage regulator is running to the dash. Checked the wires there, and they're all good too. If it's heating up like that, it will likely never close and provide current back to the battery.... Gah!
I had nearly the same mysterious symptoms and ultimately found out that the starter mount corner was about a 16th of an inch from the upper control arm pivot point which apparently after hitting some bumps push the starter toward the flex plate. A hot flex plate is larger than a cold flex plate, and as a result when it was hot the starter was binding on the flex plate but wasn't sticking it just couldn't crank being pushed up that hard to the flexplate. Trimmed about a quarter of an inch off the starter Mount and everything works perfect now.
Just skimmed through this and to clarify I am not any kind of electrician. Just what I have run into in the past. With the battery getting hot with supposedly no load, I would guess at a dead short some place, it may not be much, but that is my guess. Good luck, I hate wiring.
Ok, everything cleaned up and re-connected new voltage regulator. Checked the battery points with the car running, under RPM load the points close, then re-open. I'm gonna take it for a spin and check the charge. This is operating as I think it should now.
I liked the video, Adam. Oh yea. High five. Looks like proof to me. I'm not sure, but from where I'm sitting and what I've read, I'm wondering why you haven't given the starter a good looking over. I went back to the beginning. Hard to start when warm. Here's a thought, the magnets in the starter are weak/ broke loose and the drag from friction hard to overcome. Maybe the bushings and bearing could use a lubing. Oh, and how's your air filter? lol. Hard starting it could be a culprit.
Could be starter too, but the gar goes with a boost from a jumper. Mostly, I think charge is just not getting into the battery. I went for a drive with the new VR in place, and even though it looks to be functioning properly, the battery was 10% down from where I started after a 10min drive. Next thing to change might be the battery...
At one point you stated that you had no voltage reading at the battery. Then you said the voltage was 12.5 volts. One or the other is wrong. If the generator is charging properly you should have between 13 and 14 volts at the battery terminals with the engine running at about 1500 rpm. If you don't, there is definitely something wrong with the charging system. If you do have over 13 volts, you need to see what the battery voltage does when you try to start the car hot. If it drops below 9.6 volts, you either have a bad battery or a bad starter. If the voltage stays well above 9.6, but the starter still turns slowly, you have a voltage drop (bad connection) somewhere in the starter circuit. With the negative lead connected to the negative terminal, connect the power stud on the starter. If you read below the same voltage with the starter turning, you have a bad connection or wire. If you read the same voltage, or pretty close (within 0.2), you need to move the positive lead to the starter case. The voltmeter should not read higher than 0.2 volts, with the starter turning. If it does you have a bad ground connection. If all voltages are within the acceptable range, the starter is bad.
Clarifying the "hard start" problem - I hit the starter, and it the starter doesn't or just barely cranks, it's not that it's cranking fine and the car just won't fire. Feels like insufficient charge from the battery. Battery also fails to charge or registers a lower charge whenever I drive it, regardless of lights on/off. Starter could definitely be failing, or just refusing to crank when hot, but still tracking the ground/charge issue.
I had a similar issue with "The Judge" and it had me stumped for a while.. I had a 100 amp alternator on the car since I built it and the battery was probably four or five years old. Ever since I got it running it never did crank very fast. My dash mounted digital voltmeter was telling me that the battery never got over about 12.3 volts with the engine off. A month or two ago when I noticed that the voltmeter was showing only about 12.8 volts while operating I stopped in at a 7-Eleven and had to get a jump to start. That was the last straw so I vowed to find it. I already had a volt/ohm/ammeter clamp type that reads DC amperage. So I took voltage and amperage readings of the alternator and also at the battery terminals. Under a no load condition that is nothing but the engine running and no accessories operating at all except the ignition. I have a direct output from the alternator to the fans and also there is a branch before the battery to the fuse block. Then I took readings with everything on including headlights interior lights trunk lid light under hood light air conditioning and 1600 w sound system. All those readings still did not give me a definitive answer as to what was going on. After posting here about the subject a number of guys said it was probably my alternator giving out so I got a 160 amp alternator and put it on and it made very little difference in the readings... I thought that was very queer so I broke down and bought a brand new battery. I literally could hardly believe what the effect was because it starts and charges like a brand new off the showroom floor car... Below are the sketches I made of the readings. These are the two alternator's readings before I bought the new battery. Right after I crank the car up my in-dash ammeter nearly pegs out and since I built the car I had never seen that before... and my dash mounted voltmeter shows outputs 14.4 to 14.5 volts and then the ammeter settles down to hardly anything. It's fixed.... I hope maybe this helps. A gunched up battery that doesn't seem to be bad can be bad.
Closing the circuit on this one (ha!)... After exhausting the options for what it could have been that was inhibiting charging, including replacing the voltage regulator and the battery, I decided to take it to a local 2-man shop here in LA - Silva Auto Electric. They tested the system and found that the field coil in the rebuilt generator was too small, and not generating sufficient charge, combined with the fact that the new Duralast VR was not working. Replaced the field coil with a larger unit in the same the generator, re-replaced the OLD voltage regulator, and voila, charging as it should. Definitely something I wouldn't have been able to figure out without an advanced degree in electrical engineering, or 40 years of running an auto electric shop in LA. Highly recommend these guys, and they prefer to work on old stuff. Silva Auto Electric 323-381-6402 (ask for Oscar)
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