jlauffer

Hi all, haven't been around in a while, but need some help. Drove my car last Sunday (which was a very hot day) to my brother-in-law's house to help him with a project. Few hours later drove home. When I pulled in the driveway my son's car was blocking the garage, so I parked and shut it off. Maybe 5-10 minutes later he left, so I hopped in and tried to start it. Heard a click and then nothing...no lights, no radio, no gauge lights, nothing...totally dead as if the battery was disconnected. Pushed it back into the garage.

Battery seems fine, and there's power to the junction block. One weird thing was that a couple hours later I went to put something back in the car and when I opened the door, the interior lights came on. I was even able to put the top back up. But when I tried to start it, nothing, and everything was dead again, and has been since. After some online research, seemed like it could be the fusible link, and thought maybe even after it blew there was an intermittent connection that explained the lights and top working for a bit.

Fast forward to today, and I started digging into it. Found the fusible link and right where the link wire entered that rubbery cylinder thing, the wire seemed very floppy, so I thought that's where it blew and I had found the culprit. Silly me clipped the wire, and stripped it to see inside, only to find that it was still solid. Just in case I also tried jumping from the end of the wire to the junction block, but still nothing. So what else could be causing this? Thanks for any assistance!

72455

Have you had the battery tested? and also check the connections on your battery

Sugar Bear

May be bad connection at the battery cables. Remove and clean them at both ends. Take the negative off first and put it back last.

Invest in a multimeter or a test lamp with a voltmeter built in.

Good luck!!!

joe_padavano

^^^This. The symptoms are most likely caused by a loose or corroded battery terminal at the battery. The connection will work right up until it doesn't. Clean and tighten the clamps. That's the most likely cause and also the easiest to check, so do that first.

Koda

If, when you crank, the lights dim, or go out and stay out, it's battery. If the lights don't dim, it's the ignition circuits.

70sgeek

Check all fuses to ensure none have blown - especially anything associated with the ignition / running circuits..

jlauffer

Have an analog multimeter, which is how I checked that there's power to the junction block. But do really need to get a digital one.

There is no cranking and no lights...that's the thing. It's like the battery's not even there.

Will play around some more tomorrow...

joe_padavano

Why are people so averse to simple, logical troubleshooting? Now you have to replace a perfectly good fusible link. You need a high impedance ohmmeter. The chinesium Harbor Freight units will show 12V but won't draw enough current to test for a high resistance connection. Start with the battery terminal connectors. Clean them, tighten them. Try. If it still won't start, proceed to the starter end of the positive cable and the block end of the negative cable. Check for voltage at the starter when cranking.

By the way, have you tried jumping the car? If it starts with a jump, it's a low voltage problem, either the cables or the battery itself. Don't go out an waste the money on a new battery until you've exhausted the other possibilities, or at least use a battery load tester first.

The "hundred monkeys with a hundred typewriters" approach to finding a problem like this is guaranteed to cost more money, take more time, and probably screw up other perfectly good parts in the process.

jlauffer

Thanks Joe. I did not try jumping it...it was so dead, and happened so abruptly, I thought something must have blown. When I left my brother-in-laws, it fired right up, and was only a 20min ride home, so didn't even dawn on me that the battery could get that bad in such a short time. But lo and behold, after reading your post, I put the charger on it for a bit, jumped the wire to the junction block, and when I opened the door the interior lights came on, and when I turned the key the Oil and Gen lights came on and I was able to turn on the radio. So yes, now I feel like an idiot. I will check the battery cables, replace the fusible link, and go from there. Thanks again!

tkcutlass

Did you happen to have the lights, radio, and wipers on when driving home or A/C on high perhaps?
Perhaps your charging system should be checked.

jlauffer

Was during the day and not raining, so only the radio was on (AC doesn't work). But it certainly wouldn't hurt to check that too.

jlauffer

Took a couple weeks to get back to it, but I replaced the fusible link, got a digital meter, charged the battery, and it still wouldn't do anything...no click click click, nothing. My charger has a Start function, and when I tried that all I got was the click click click. So next I tried jumping it and was finally able to get it started. While running it was showing 13.7V, so I'm figuring the charging system is OK? Ended up getting a new battery, which was it's own little ordeal. Parts place said Group 78, but that has side terminals and mine has top terminals. Another guy overhears us and says Group 34 is the same thing but with top terminals, so tried that. Wouldn't work with the clamp-down bracket. But noticed after taking the old battery out that it was marked as Group 48, so went back and got one of those and that did the trick. Dropped it in and she fired right up.

Vintage Chief

Now, w/ a new battery and a new digital meter, what is the voltage at the battery when the car is running? It should read ~14.3V or >14.3V but <15.0V.

Vintage Chief

BTW, after some time considering your ordeal, just dropping in a new battery "might" be the quick answer in resolving your issue for the short-term. As others have already stated, you should still remove your battery terminal wires - all of them which connect to the battery (that would include the wire(s) to the horn relay junction/distribution block, ground wire to the chassis/frame (near the radiator shroud), the ground/battery terminal to the engine block & the battery terminal wire(s) at the starter). Clean the terminal ends with a wire brush, clean the battery terminal ends with a pocket knife/wire brush down to new fresh metal. Clean the metal where the wire terminals attache. Corroded/Oxidized wires are the plague to vintage car electrical systems; yet, very easy to perform maintenance on.

droldsmorland

Did you inspect/clean both ends of the positive & negative cables? Are they in good shape? If original probably not. Replace with OEM parts!
Then bench test the starter & solenoid.
The contact bushing in the solenoid could be pitted. Or the starter needs a refresh. Next time you run into a similar situation give the starter the hammer test. If it starts there's part of the problem.

A new battery will (if you're lucky) mask the bigger problem(s).

The starting & charging systems have to be inspected if you want reliability.

jlauffer

Read 13.67V yesterday, and I had found a previous post on this site that said it should be between 13.5 and 14, so thought I was good. However, took it for a short ride today and then checked it, and it started around 13.35V and then was dropping by 0.01V every 5 seconds or so...shut it off when it got down to 13.25. So still seems to be a problem somewhere. Thoughts? I did check/clean the cables.

Figures, my son starts college in the fall and I was looking to sell the car...

Sugar Bear

Can you post a picture of the alternator including its' plug?

jlauffer

Here you go:

Sugar Bear

That is an external type voltage regulator alternator. The voltage regulator is not inside the alternator, it is mounted on the firewall and is easily replaced. The alternator could be removed, taken to an auto store and tested OR you could try a new voltage regulator. The voltage regulator controls the alternator output, a defective voltage regulator can cause the alternator to overcharge or not charge at all.

The voltage regulator can also be bypassed for a few seconds to see if the alternator charges.

Vintage Chief

I expect to see generally a range of 14.3V - 14.7V for an alternator when charging your car. You stated ~13.5 & dropping 0.01V every 5 seconds or so...(when you) shut it off when it got down to 13.25. That's an alternator not performing it's job. I'd generally expect to see a bad VR if the voltage were >15.0V. When it fails to charge above 14.0V I suspect the alternator.

Here's a good test of the alternator for a home mechanic.

Ensure the battery is fully charged (~12.6V). Hook up the DMM (Digital Multi Meter) to the battery & set to voltage as you normally would. Start the vehicle. Measure the voltage. Slowly increase the RPM of the engine to ~2000RPM - 2500RPM & monitor the DMM voltage. You should see the voltage either maintaining itself or increasing until it increases no longer - monitor that voltage number. Next, more importantly place a load on the alternator. To to this, keep the engine running (at idle) note the voltage, turn on the headlights, the AC (if equipped), the radio, the heater, etc. and note the voltage. The voltage should not at any time fall below 13.0V - if it does, the alternator is bad. The alternator should suffer some drop in voltage, but a properly performing alternator should never fall below 13.0V. As soon as you validate the voltage with everything running, turn off the accessories (removing the load). If the voltage remains low (i.e. ~13V) it's a bad alternator. If this simple test turns out to demonstrate you can't achieve a charging voltage of ~14.0V or greater, drive the car to a auto parts store. Have them perform a load test on the alternator. They'll do this for free. I suspect a bad alternator.

jlauffer

Voltage while increasing RPM topped out at 13.66V and then went to about 13.5V at idle. As before, voltage then started dropping. Turned on the headlights, high beams, and radio, and it eventually dropped to 12.97V and then I turned off the loads. Voltage went up to 13.3V and then started dropping again. Also during this I tried increasing the RPM again and the voltage did not change this time (was at 13.16V when I did it). Let it drop to 12.90V and then shut off the car.

Before doing the above, I had found a post by droldsmorland from 2015 that had various things to check, and I did the following:
1. With the car off and regulator harness unplugged, checked for voltage at all 4 terminals. Had battery voltage at #3 as expected, but also had 1V at #2. His post said if there was any voltage on #2 it pointed to a leaky diode in the alternator.
2. Turn the key and had battery voltage at #4 as expected.
3. Started the car and momentarily jumped F to #3 and the voltage went over 15V.
4. When I plugged the regulator harness back in, the voltage went to 14.15V and seemed steady for a bit so had a glimmer of hope, but then started dropping again.

So based on voltage being present at the #2 regulator terminal, and the fact that the voltage drops below 13V, sounding like the alternator?

Vintage Chief

Yes

droldsmorland

As I stated check the pos & neg wire connections. Check the connections at the rear of the alternator. Check the connections at the VReg. The body of the regulator grounds to the firewall. Remove it and reinstall it. Just disturbing the two screws will increase the ground. Should be two star washers on the one screw. One between the VR and firewall.

Physically clean all the above connections. Then retest things. 14.0VDC +/- .3 is what you want. So 13.7 is the lowest acceptable reading on the minus side.

There should be a ground strap on the passenger side head to the firewall.

Take the Alt and VR to a known good rebuild shop and have them tested as a set. If it's an original alternator and it tests bad have it rebuild. Don't turn in the core for a big box replacement.

That negative wire going to the block under the alternator looks like a cheapy replacement or a shotty attempt at a crimp. Again the pos & ned wires should be clean on both ends.

I have an updated regulator test I'll dig out.

72455

How about the old school test of disconnecting the negative battery cable while it's running? If it shuts down, then it's the alternator.

Sugar Bear

Disconnecting the battery to see if it continues to run will tell us if it's charging, in this case it's an external regulator so it could be the alternator, regulator, both or wiring.

Good luck!!!

Vintage Chief

There’s a test you can do on both the negative & positive sides of the alternator (voltage drop) to address either negative or positive wiring issues but I’m too lazy to write it up on my phone because I’m a couch potato watching ‘Dirty Harry’ at the moment and on my phone.

Sugar Bear

TEMPORARILY for TESTING, you could remove the plug from the voltage regulator, jumper the F terminal wire to the 3 terminal on the voltage regulator plug, start the car and measure voltage across the battery. This takes the voltage regulator out of the circuit so the charging is continuous and unlimited/uncontrolled. If it charges the voltage regulator is bad, if it does not charge the voltage regulator may or may not be bad but the alternator is definitely not working assuming the wiring is good.

Is the belt in good condition and snug? If the alternator pulley gets HOT, the belt is slipping.

Follow the suggestions to clean and tighten connections.

Good luck!!!

matt69olds

Don't do this!!!

This “test” is pointless!!! At most, an ignition system at idle takes a couple amps to run. A charging system putting out a few amps isn’t working correctly. Not to mention the voltage spike from disconnecting or reconnecting battery cables can cause damage to electrical components. I’m pretty sure this “test” procedure is plainly and clearly not recommended in every service manual ever printed. Not to mention the clear warning printed on every battery about creating sparks near the battery.

Dynoking

Disconnecting the battery with the engine running is not recommenced for all the reasons listed in post 28, additionally the diodes in the alternator can be damaged.
In post 21 the OP states "Started the car and momentarily jumped F to #3 and the voltage went over 15V." This is called the regulator bypass test. The results clearly indicate a working alternator and charging system wiring. If I were under the hood I would replace the voltage regulator with a OEM or AC Delco VR and retest charging system output.

Sugar Bear

Missed #21, yes the voltage regulator needs to be replaced.

droldsmorland

After basic a clean up and inspection, apply load to the system. That is the route a rebuild shop will take.
The system's ability to hold up under load, particularly hot load is where you find the weakest link. Electrical systems break down. Additive factors include but are not limited too,,,, corrosion, age dirt wrong parts etc

While idling, turn on all lights. Put blower on high. Read volts...13.6ish....now idle it up to fast idle 1500ish. Reading 14+ish? You are likely OK.
Load test the battery too,

jlauffer

Last weekend I cleaned the wiring at the junction block and alternator, and also removed the voltage regulator and cleaned the contact points on the firewall. Didn't make a difference. Replaced the voltage regulator today and that seemed to do the trick. Was reading 14.19V when I first started it, and over maybe 6-7min of running it was at 14.13V (before it would have dropped well under 13V in that timeframe). Then took it for a 15-20min ride and was reading a steady 13.9V when I got back. I've had the car for 7 years and now I'm thinking this was actually an issue all along and the battery finally had enough. The car starts much better now than it ever did, and even seems to run better...actually had to turn down the idle.

Thanks again for all the help!

Sugar Bear

Good work! It probably does run better, the correct primary voltage to the coil results in the correct secondary/high voltage to the plugs.

Drive it!!!

droldsmorland

Jlauffer 1 car 0.
Glad it worked out.
Take it to the goal line and replace the Pos & Neg cables with correct OEMs from one of the many known resto house suppliers Clean up the connections at the starter while you're there.