68 442 convertible, 455, Th400, no AC Ext. regulated. So, I got stuck at the gas station Thursday night. Went to start it and nothing. I did notice it sounding weak the start before. I was able to jump it and get home. I put the battery on a slow charge for 24 hrs. Battery was @ 12.86 volts on the DMM. with the car off. I turned the car on and I was still getting 12.6. Took it for a couple short rides. check voltage with car off, 12.7, 12.5, 12.3. Going down each time. I think with the Car running I should have 14 volts+-. Also did a parasitic drain test and that passed well. Thanks Vintage Chief for posting that. I have an extra alt and regulator but don't want to change it out unless needed. An opinion on where to start would be helpful. Thanks. Greg

 

13.8-14.2VDC with a fully charged battery and the car running. Is it still stock? External regulator on the firewall or internal to the regulator?

 

Regulator stock on the firewall. Thanks for the reply

 

Greg - As Jeff (Sugar Bear) suggested measure voltage at the battery w/ car running, all accessories OFF (e.g. AC, lights, radio, heater, etc.) & note total voltage being delivered at the battery from the ALT. I don't recall/know which ALT was stock/OEM for a 1968 442. Nearly certain it was delivered w/ and external VR, but the 442 I believe received the bigger/beefier ALT. In any case, the ALT may have been changed during the past 50+ years; therefore, validate what ALT you have as Jeff suggested, possible it's been converted to an ALT w/ internal VR. Which, in that case it's possible to suspect a leaking diode w/in the ALT. Get the total voltage measured at the battery w/ car running first.

 

Total voltage output as read at the battery w/ car running?.

 

If the battery is losing voltage for no apparent reason, it's probably going bad internally.

 

As Eric noted...

Examine the battery for a year/month date code - may require battery removal.

You most likely already know this, but...

 

OK, Battery is about a year and a half old. I'll need to bring it in for a test. Being at 12.8 after charging I was thinking its probably ok. Will check it though. Just started it up and its at 12.3 running. 12.4 with car off. Been getting these same readings all day. Slowly dropping. Just to clear this up. there is not of original in this car. I was saying it has a stock style regulator not solid state. Alt is a 1100843. 71 rebuilt.

 

Jumper terminals F to 3 at the VR, start the car and re- test the voltage output at the battery, the jumper bypasses the regulator. Don't leave it this way it will fry the battery, just do it for the test.

 

 

If you are not getting 13.8 to 14.5 volts at the battery with the car running, you have either a bad VR, bad alternator, or a wiring issue.

 

This only happens when running. Seems as though its just not charging. Drove it a good 10 miles today when trouble shooting. Its not dropping quickly. I'll get the Battery tested to be sure. Greg

 

You can test the charging system to rule out the VR by following post #9. That is a 61 amp output externally regulated alternator.

The wiring has been redone, it looks a nice clean wiring repair sans original plugs.
​​​​​​

 

I was thinking the same. I have been all over the wiring (I know it looks a little shabby still a work in progress) I have good confidence in it now. Just do not want to see a good reg./alt get wasted.

 

Sugar Bear The jumper is done with the Regulator plugged in? Or unplugged and and F and 3 connected. I think I know but checking.

 

Unplugged

 

The wiring looks good just not original. Confirm that the terminals are clean and tight.

 

Wire diagram has the bottom blue wire as the f terminal. Witch is the 3 wire?

 

Should be molded on the VR plug. If you cannot find it jumper 12V from the batt to the F terminal/wire. IIRC the 3 is two over from the F, essentially F,2,3,4 on the plug.

 

Sorry blue wire into F terminal. #3 is probably the white wire from Alt, But I'll wait on response.

 

ok got it . Thanks

 

So , jumped the red wire#3, to the f terminal car running 12.3 volts

 

Jump the F terminal on the back of the alt to batt direct and retest.

 

Leaving the regulator jumped Or re assemble?

 

Shouldn't matter.

 

Measure voltage with car off with all wires connected at the battery terminal on the back of alt. and then across the batt should be the same.

 

F terminal to + battery 13.5 Jumpy but maybe going up slightly.

 

Sugar Bear, I did not see your post 26 until after i did the last test. The car was running when tested. Was post 26 to be done after alt f terminal to battery test?

 

V should have gone higher when jumped. I should have told you this sorry...what is the V with direct battery to F AND the idle increased? Should be 14.5VDC or better unless the battery charge is low.

 

If the V doesn't come up when jumped with idle increased AND we assume the wiring is good AND the battery is fully charged, the alternator is weak.

We cannot at home test the VR without a solid alternator output so we don't know if it is good or bad.

 

When I bring up the idle it goes up to 14.5

 

14.5 is good. The alternator is putting out sufficient V. Go back to jumping F to 3 at the VR with the idle up and check V across the battery.

 

Leave the Alt, Jumper?

 

No reconnect the alternator as it was, unplug VR, jumper F to 3, leave VR unplugged, raise idle and check V across battery and back of alt batt terminal.

 

F terminal to #3 = 12.26v stayed steady when idle was increased.

 

Bad VR.

 

Confirm that 3 at the VR gets batt voltage.

 

Confirmed 12.3. Thank you for taking time on your Sat. Night to walk me through this. Don't know how many threads I've read that just never came to a conclusion. Enjoy the rest of your weekend and I'll follow up when fixed.

 

You are welcome.

Here is what we KNOW, the VR is bad AND the alternator is producing sufficient V. We have also mostly ruled out wiring from testing from the alt directly and through wire harness at the VR.

Here is what we DO NOT know and have to assume for now that is ok, we don't have the equipment to test the alternator amperage output but it is probably fine.

Replace the VR, go quality on the part, fully recharge the battery, raise the idle and retest V at the alt output stud and across the battery.
​​​​​
​​​​​

 

I'll try and finish up tomorrow. Thanks again. Greg