Ammeter problem

[normanpitkin]

hi, my 1948 New Yorker has developed an annoying problem, recently fitted a completely rebuilt generator and now not only does the ammeter bounce all over the place intermittently but when hot the motor barely turns over ,which it never did before .I think the car is charging and when cold or just warm starts instantly .Im thinking I need a new voltage regulator ,thoughts from any electrical geniuses out there? Is the voltage regulator the same for the New Yorker as the Windsor?

[Bryan]

Need my coffee first, just got up.   There are posts about polarizing the generator by briefly shorting 2 terminals on the regulator. Just don't know which two.  Since you probably had to disconnect the battery cables when you took the generator out, I would recheck the battery connections first.

[normanpitkin]

no ,the battery leads are correctly placed and the ammeter is fine on start up ,its only when it gets hot ,maybe the coil?

[Bryan]

Try going through this post from start to finish. He had the same type of problem.  

 

[normanpitkin]

yes ,I've read that ,checked all connections   ,all are ok ,its only hardly turning over when its hot. When cold it turns over like new ,I have had the car a long time and its only started to do this after the generator was rebuilt. only thing i haven't done is got a new voltage regulator

 ,could it be this?

[kencombs]

First things first.  Determine the battery condition and state of charge.  Check for voltage drop when cranking.  There is a very good procedure outlined on this site, by Sniper I believe.  Then measure voltage when static and when running.   Those pieces of info will lead to a diagnosis.  Without that, one can only guess.  

 

edit to add:  I don't normally recommend or do this, but most parts stores have a free service and will attach a meter to your car and analyze the charging system.  But, I have no idea if there tools work on 6v systems. 

Edited May 1, 2022 by kencombs

[normanpitkin]

battery is new ,cross tested in my 1941 and holds perfect charge. 

 

[keithb7]

When hot barely turns over. Do you mean the generator barely turns over when hot? Or the engine barely turns over when hot?

Who rebuilt this generator? Was it your old one sent it and rebuilt? 

 

The generator field windings do need to be polarized when a battery has been disconnected for a while. This action gets the positive and negative ends sorted out so the proper magnetic field is created.  If not,  a weak or no magnetic field is created by the field windings and little to no output amps are created by the generator.

 

If the battery is good, and the engine barely turns over when hot, I think a short to ground could be occurring. Somewhere in the system between the battery and the starter circuit. A person should have a multi-meter to run some quick checks. Ideally a clamp style ammeter for DC voltage. At a minimum at DC voltmeter so you can read your battery voltage and confirm the battery voltage before and after starting the engine. The clamp style ammeter will show you exact ammeter out put.

Edited May 1, 2022 by keithb7

[Sniper]

First things first.  You need to break out eh voltmeter and measure the battery voltage with the engine off.  Then measure it with the engine running and the charging system working.  Then see if you can replicate the issue and measure the voltage again, engine off and engine running.  This will narrow the issue down.  But frankly, if the ammeter is getting wonky that's pretty much an indication that you charging system isn't doing it's job properly.

 

There have been plenty of times when something electrical worked fine, till it heated up.  Once you sort out the above measurements we can look at the voltage regulator control going to the generator.  If those are flaky then that's what is making the ammeter dance.

 

Voltage drop test Ken mentioned 

m

[OUTFXD]

I STILL have starting issues. Starter turns freely in the morning for about 5 seconds.  for the rest of the day it sounds like a dead battery UNLESS hooked to a 12v battery.  I got her aligned Friday and the Mechanic Confirmed the battery was fully charged and the charging system was working.  ITs not like this is Rocket science, Its Babys first electric circuit.  One Battery,  One Switch, one motor.  I am down to thinking the windings or field coils in the starter are going bad.

 

The Ammeter makes me think 1) make sure your Fan belt is tight and 2) check the voltage regulator. Possible to check with the voltage regulator from your 41?

[harmony]

I'm going to ask a question that hasn't been asked yet.  At the risk of stepping into deep water without a life jacket since I'm stupider than a stick when it comes to electricity.  However,,,  my question is why did you get the generator rebuilt?  What was going on with the charging system that made you think it needed rebuilding?

Sniper mentioned that if the ammeter is going all wonky, then the charging system isn't working. Which brought back a painfully costly memory.

 

Your problem is of particular interest to me because I had the generator on my parts car rebuilt. Same kind of  generator rated at 22. With the same engine with the same regulator off a 46 Windsor.   Even though my generator on my 48 Windsor was working ok.  ( yep I needed my head read) When I put the newly rebuilt generator on my car, the amp gauge seemed higher than normal at idle.  Half way between 0 and +35.  Normally at idle it's usually just barely above 0.  I took the car for a (very short) test drive and as I got up to speed the amp gauge was showing +35.  I pulled my light on and it dropped to -35.  I returned to my shop and the gauge started jumping all over the place, when I used my turn signal.  I called the guys that rebuilt it and they blamed the regulator.  I put the original generator back on the car and everything was normal again.  I keep telling myself to buy a new regulator to match it up with the rebuilt generator, but it keeps slipping my mind.  Or maybe I'm just too cheap to buy a new regulator that's made in China.   Plus I'm still licking my wounds after spending $325 to have parts car generator rebuilt.   So it's just collecting dust.  

Edited May 3, 2022 by harmony

[Bryan]

9 hours ago, OUTFXD said:

The Ammeter makes me think 1) make sure your Fan belt is tight and 2) check the voltage regulator. Possible to check with the voltage regulator from your 41?

Think if the belt was loose, it just wouldn't charge properly.  The gauge probably wouldn't jump around.  Generator, regulator, or a connection.

[Pete]

Could the engine be hydrolocking from fuel in the cylinders?

 

Pete

 

 

[normanpitkin]

I have called in the cavalry ,phil who is in his late 70s ! He thinks its either the regulator or the starter brushes !  Perhaps even the ammeter itself

we shall see ,watch this space ,he is coming round with his meters and more importantly ,his brain.

[Bryan]

55 minutes ago, normanpitkin said:

I have called in the cavalry ,phil who is in his late 70s ! He thinks its either the regulator or the starter brushes !  Perhaps even the ammeter itself

we shall see ,watch this space ,he is coming round with his meters and more importantly ,his brain.

I'm betting on the generator if nothing else was touched during the replacement.. Have you tried charging the battery fully with a separate charger overnight (terminals off), then seeing how the car starts after it gets hot?

[normanpitkin]

Generator has just been rebuilt and correctly installed  ,battery is new and also tested .

[kencombs]

The voltage drop tests mentioned earlier in the discussion can help separate the possible causes, starter problems or cable problems, connection issues etc etc.  Lots of good info here:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi4kOiy_cP3AhXammoFHbqaD8gQFnoECAwQAw&url=https%3A%2F%2Fwww.alldata.com%2Fmx%2Fen%2Fsupport%2Ftech-assist%2Farticle%2Fvoltage-drop-testing&usg=AOvVaw0P5a26OBcRE6yzOaTegdmX

In case it could be excessive starter draw when hot that can be checked with an appropriate ammeter.  But I really doubt that due to the other erratic amp readings from the dash gauge.  Intermittent charging could be a bad ground somewhere, defective connection, voltage regulator or sticky generator brushes due.  A meter, a test plan and time is the only way to effectively sort things like this out.  That or swapping with known good  parts.