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I've been fighting a discharge on my 80C for quite some time. I've replaced generators multiple times, voltage regulators numerous times I even had one converted to solid state.

 

Typically what's happening currently is I have charging on the gauge for a bit of driving and then eventually I show a discharge. If I can get the engine revd up enough it will charge. I used to think this was normal but when I got my 87 which works well I determined it's not. I've swapped VRs back and forth between cars to no effect on the 80C.

 

 

Currently showing a discharge with ignition off also the same at low RPM. See belowIMG_20200726_112138.thumb.jpg.c3404f98b62cf5b02e2fbe36e3640933.jpg

 

Today I started to systematically disconnect stuff.

First the rear harness

 

Next all the lighting at the terminal blocks on the lights, then all at the switch.

 

Also all the instrument/map/clock wiring too

 

No effect, in fact the picture above is after all that.

 

Next is heater and defroster switches and the Triple lights. That leaves electric fuel pump (which is being the ignition switch) and the starting relay wiring. I have never replaced the starter and solenoid, the 87 is in storage so can't swap that one in but I may have to.

 

What am I forgetting?

 

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A wire with burnt insulation that is now grounding?  Clock ? Didnt leave the radio on?  

As a separate thought if the radio is connected, has the cloth covered power wire been replaced? 

 

Good luck!

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9 minutes ago, Bloo said:

Is this picture with the engine running or off? Is the ignition switch on or off?

ignition off thus engine off.

 

21 minutes ago, JohnD1956 said:

A wire with burnt insulation that is now grounding?  Clock ? Didnt leave the radio on?  

As a separate thought if the radio is connected, has the cloth covered power wire been replaced? 

 

Good luck!

 

clock disconnected no difference. radio is off, connected, have to think about the wire. be back on that.

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The autostart wiring (small wiring) is not live with the ignition off. About the only thing left is the starter and the horn.

 

2 minutes ago, 38Buick 80C said:

Friend suggested with ignition off taking wire off battery terminal and touching it to terminal if I noticed a spark I have a draw. It did NOT spark.

 

That doesn't quite add up. Did it make the ammeter go to center when you disconnected? Did it go back to discharge when you hooked it back up?

 

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1 minute ago, Bloo said:

The autostart wiring (small wiring) is not live with the ignition off. About the only thing left is the starter and the horn.

 

 

That doesn't quite add up. Did it make the ammeter go to center when you disconnected? Did it go back to discharge when you hooked it back up?

 

 

no gauge remains unchanged with battery disconnected, looks like the photos from before showing discharge...

 

must be the gauge then right...

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Yeah. There just about HAS to be something wrong with the gauge. With the engine off and the battery disconnected, theres nothing to power it. Default is center.

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Swapped the gauge out with an NOS one.

 

Gauge in the car definitely had an issue.IMG_20200726_150941.thumb.jpg.a8bce14d6111c394c0370435f56db172.jpg

 

Still concerned about how it runs.

 

Here is a video of idle and being revd up

Is that normal? I know my idle is a little slow.

 

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21 minutes ago, critterpainter said:

A discharge or a flutter on the gauge is normal at idle.  It may have been camera (phone) angle, but I did not see a strong charge when the engine was reved up.

correct. Charge was basically just above the line, no matter rev. when positive.

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So when you put the VR from the 80C on the 87 it worked properly on the 87?    My gut feeling is the Gen on the 80C is having an issue or is a later unit.  I no longer have access to shop manuals but the wiring inside a 1938 generator is NOT the same as 1941? or later.   

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44 minutes ago, critterpainter said:

So when you put the VR from the 80C on the 87 it worked properly on the 87?

 

correct

 

44 minutes ago, critterpainter said:

 the wiring inside a 1938 generator is NOT the same as 1941? or later.   

that I don't know off my head but the regulators are very different 38 was the one year only 5 post. A 4 post regulator will work on a 38 disconnecting one wire

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I would expect the swing to the positive side to be higher. I would think that the issue is the Generator unless there is something shorted elsewhere. It appears to be working, but not putting out the amperage that I would expect it to put out, based on my experience with mine. 

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I'm not familiar with your vintage of Buick, I see one line on either side of zero, I assume with a generator max on the gauge is 20 amps in either direction? 

 

My 27 generator is always putting out something even at low idle, but due to the ignition and electric fuel pump, it can be a discharge of a few amps.  At fast idle or over the road with a hot generator, I'm charging about 9 amps.  Cold generator, over 15 amps. 

 

Screenshot_20200726-174304.thumb.png.7fcbba079db831e4243a360188537921.png

 

Under any condition,  my amp gauge is never maxed out either charge or discharge. 

 

It looks like your gauge is close to pinned on the discharge side. 

 

Is the YouTube video with the new NOS gauge,  or with the old one that doesn't zero out? 

Edited by 27donb (see edit history)
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Compare the generator part # on the two cars.   I have a strong hunch you have a later generator on the "problem child"  Did it ever have a 3 wire voltage regulator on it with a working charging system?  You might want to have Bob check the application of the generator on the car.

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Hello Brian et al,

 

I would suggest a couple of things, based on what you've done to this point:

  • You don't ever mention the battery or it's condition.  In order for the voltage regulator and ammeter to work properly the battery must be fully charged and in otherwise good condition.  Keep in mind that the voltage regulator points open and close based on the voltage from the generator exceeding the battery voltage.  If the battery has a problem with sulfation of the  plates, it's possible that the battery voltage is inconsistent, which will cause all kinds of strange problems. Given that I've replaced two batteries recently, one an Optima, that were around 3 yrs old, you may want to consider replacing the battery if it's more than a couple of years old.
  • Check the status of the ground between the engine, chassis and body.  The best way to do this is to use your VOM to see if there is any voltage between the engine, chassis and body.  There should be 0 volts.  If there is any voltage passing between these components, you have a ground problem.  You can also do this test while turning different components on and off.  If the reading changes when you energize any other device, you are getting a ground path through that device which should never happen.
  • The 5-pole regulator was only used for a couple of years (my  1937 should have had one).  They were known to be unreliable and were replaced with the more common 3 or 4 pole regulators.  The two additional poles on the 5-pole function as a secondary interlock to prevent the starter from engaging when the engine is running.  When the generator begins producing current, the relay inside the regulator opens, disconnecting one of the current sources to the starter solenoid.  There is a "buick approved" workaround that was issued in a service bulletin in the late 1940s to allow use of of a 3-pole regulator on these cars.  This is what I have done on my 66C and everything works as it should.

Let us know what you find. 

 

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21 minutes ago, critterpainter said:

Compare the generator part # on the two cars.   I have a strong hunch you have a later generator on the "problem child"  Did it ever have a 3 wire voltage regulator on it with a working charging system?  You might want to have Bob check the application of the generator on the car.

to be clear both cars are 38's

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14 minutes ago, 1937 Buick 66C said:

Hello Brian et al,

 

I would suggest a couple of things, based on what you've done to this point:

  • You don't ever mention the battery or it's condition.  In order for the voltage regulator and ammeter to work properly the battery must be fully charged and in otherwise good condition.  Keep in mind that the voltage regulator points open and close based on the voltage from the generator exceeding the battery voltage.  If the battery has a problem with sulfation of the  plates, it's possible that the battery voltage is inconsistent, which will cause all kinds of strange problems. Given that I've replaced two batteries recently, one an Optima, that were around 3 yrs old, you may want to consider replacing the battery if it's more than a couple of years old.
  • Check the status of the ground between the engine, chassis and body.  The best way to do this is to use your VOM to see if there is any voltage between the engine, chassis and body.  There should be 0 volts.  If there is any voltage passing between these components, you have a ground problem.  You can also do this test while turning different components on and off.  If the reading changes when you energize any other device, you are getting a ground path through that device which should never happen.
  • The 5-pole regulator was only used for a couple of years (my  1937 should have had one).  They were known to be unreliable and were replaced with the more common 3 or 4 pole regulators.  The two additional poles on the 5-pole function as a secondary interlock to prevent the starter from engaging when the engine is running.  When the generator begins producing current, the relay inside the regulator opens, disconnecting one of the current sources to the starter solenoid.  There is a "buick approved" workaround that was issued in a service bulletin in the late 1940s to allow use of of a 3-pole regulator on these cars.  This is what I have done on my 66C and everything works as it should.

Let us know what you find. 

 

 battery is relatively new and always on a tender

 

ok will check that

 

I had 2 of my 5 post regulators converted to solid state. after switching gauges I eventually switched to solid state VR and got basically the same result. I'm confident it is not the VR.

33 minutes ago, 27donb said:

Is the YouTube video with the new NOS gauge,  or with the old one that doesn't zero out? 

 

with the NOS gauge, but before i switched to the solid state VR.

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Two things to try.  

1. Disconnect the battery and then reconnect the battery and see if the draw is still there or does it go away.

2. If the draw is still there, put an ampmeter between the battery + terminal and the cable. Is there still a draw?  If so, then I would start disconnecting items until the draw on the amp meter at the battery goes away.  The first thing that I would disconnect is the wire at the distributor that goes to the coil.

 

Just my thoughts.

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2 minutes ago, 27donb said:

A volt meter, directly on the battery, can reveal a lot.  Battery voltage before starting, at idle, at high idle, with lights on, and compare to what the dash gauge indicates. 

 

This is usually my first step when I think something is hinkey with the charging system. You'll know if the power is getting to the battery like it should and whether the battery is healthy. You should get 7.5+ volts at 2000 RPM or so. You can also ground the field terminal, which will make the generator go to full output, which will tell you if it's capable of delivering the proper output. It will at least narrow down the list of suspects.

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 I wouldn't go so far as to call a Delco 5-terminal 'unreliable". Yes, I know GM did. I have been driving around on one for almost 3 years and I don't see any reason to change it. I have a theory why they said that, but it isn't really relevant to the problem at hand.

 

Set properly, the 5-terminal should have about 7.65 Volts running at something above idle, on a room-temperature day. It will overshoot that for the first block or two while the system catches up after starting. The regulator is overcompensated for temperature, so it will probably be somewhat less than 7.65 in hot weather or after the engine has been blowing hot air on it for a while. Below 7.2 would really raise my eyebrows, and I would expect something more like 7.4 even when hot. This is above idle or driving, with a charged battery, and accessories and lights off.

 

I doubt the meter is going to work on this car with the engine running, but it's worth a try. It would be great information to have. If not, do you have a generator test set or some other analog meter that can tell the difference between about 6.3 volts and about 7.5 volts? Maybe an analog VOM? Check voltage at the battery with the engine revved up off idle.

 

In the video, the gauge goes way to the discharge side. Does it center with the car off now? When does it go all the way to discharge? Does it do that when you first turn the ignition on, or does it discharge more after you start the engine?

 

The fact that it doesn't go that far into "charge" could be normal since the battery is fully charged.

 

Edited by Bloo (see edit history)
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I have a 1941 with a different gauge (charge + on right, discharge - on left) but I believe the

response of any gauge should be the same upon startup and shutoff.

I have a short video that shows how I think it should work: 

I also do not see a strong charge when revving the engine. I suspect that

if the battery is already well charged revving should not show a charge surge

because the voltage regulator prevents that. 

 

Also I agree there should be no electrical draw with the engine off and the ignition

switch in the off position. The spark test you did does point to a short somewhere

even though you seem to have eliminated all systems. Did you disconnect the

electric fuel pump wiring to see if that has a problem? Have you added any

extra switches like a kill switch or fuel pump switch? Switches do go bad. I have

had that happen. And as mentioned it may just be a bad meter.

 

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Brian,

Is the "drain" causing the battery to go dead with the key off?  If so, the only reliable place to check for a draw is with an amp meter between the positive battery terminal and the disconnected from the battery, the positive battery cable.  Everything else is just guessing.

 

If there is a drain at the battery with the ignition off, then you can start disconnecting the different wires until the drain is gone.  

 

Once you disconnect a wire and the drain is gone, then start connecting the other wires that you disconnected prior to the one wire that caused the drain to go away.  This way you will be able to maybe determine if there is any feedback circuit that might be causing an additional back feed drain.  

 

This is just the way that I would systematically determine the cause of the problem. 

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Draw between battery lead and terminal 0.05mA which seems to be fine  (confirms my spark test of NO sparking)

before start Voltage 6.54

slow idle voltage ( showing discharge on the gauge) 6.35 (slow idle is VERY slow, will check RPM, but you can nearly count the fan blades)

fast idle voltage ( showing just above zero on the gauge) 7.49

forgot to do it with the lights on

 

grounding the field terminal ( on the regulator to a a ground? or on the generator to a ground?)

 

didn't dare put mess around under the dash any more to put an known properly reading ammeter in the series, but I hear ya on false reading. 

 

No lack of power to start after a drive and coincidentally unlike a lot of my cars (all on battery tenders) when re plugged into the battery tender immediately goes green where my other cars are either red briefly and then go flashing green or are at flashing green.

 

I'm pretty satisfied actually after changing the gauge. I don't think I am going to mess with it much more. Unless someone see an issue with the data above?

 

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On 8/2/2020 at 5:26 AM, 38Buick 80C said:

RPM is 325 at slow idle


Brian, I think I have read in a later shop manual idle should be 400rpm. I know the ‘38 manual quotes MPH as a guide, but that’s hard to do  sitting in the garage. Possibly diagnostic tachometers were not used until late pre-war or post war. Others might chime in to confirm the rpm.

Rodney 😀😀😀😀😀😀

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On 8/1/2020 at 12:48 PM, 38Buick 80C said:

slow idle voltage ( showing discharge on the gauge) 6.35 (slow idle is VERY slow, will check RPM, but you can nearly count the fan blades)

fast idle voltage ( showing just above zero on the gauge) 7.49

forgot to do it with the lights on

 

grounding the field terminal ( on the regulator to a a ground? or on the generator to a ground?)

 

 

Thats a bit confusing. If you had to ground the field to get 7.49, you may still have a problem. If you just revved it up to fast idle and got 7.49 it sounds normal to me.

 

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8 hours ago, Bloo said:

 

Thats a bit confusing. If you had to ground the field to get 7.49, you may still have a problem. If you just revved it up to fast idle and got 7.49 it sounds normal to me.

 

 

 I just rev'd it up.

 

I wasn't sure about how/where to properly ground the field so that wasn't done.

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