Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks


Previous Thread
Next Thread
Print Thread
Rate Thread
#468623 04/03/22 08:10 AM
Joined: Oct 2021
Posts: 39
Ted1956 Offline OP
Shade Tree Mechanic
OP Offline
Shade Tree Mechanic
Joined: Oct 2021
Posts: 39
Still attempting to put the 31 Independence on the road for this summer. Next on the agenda is the ammeter gauge. The dial is pegged at -10. No movement either sitting or on the road. Checked the cut out and it functions okay. Not certain if it's the generator or the gauge itself. The dial has two terminals on the back side. One side has three wires attached and the other a single which appears to be going to the light switch, The fuse inline is good. Can an ammeter be repaired easily or need be sent out or replaced?


TedG
Filling Station - Chevrolet & GMC Reproduction Parts


Filling Station


Ted1956 #468626 04/03/22 09:32 AM
Joined: Apr 2010
Posts: 734
Likes: 14
Oil Can Mechanic
Offline
Oil Can Mechanic
Joined: Apr 2010
Posts: 734
Likes: 14
Hello Ted1956,
Not all that knowledgeable when it comes to electrical issues so I think that isolating the ammeter is what might be the first thing to investigate. Computer search '1931 chevy wiring diagram' for reference if needed. Before unhooking any wires, and the vehicle turned off and all electrically powered items of the vehicle turned off, does the ammeter still indicate neg -10 amps? Would you not think that your battery voltage be depleted rapidly? Does that happen? If you disconnect the battery, does the ammeter still indicate neg -10 amps? If so, I would suspect issues with the ammeter gauge itself. If the ammeter changes it's indication when the battery is disconnected, issues may be elsewhere within the electrical system. I do not know if an ammeter can be repaired if determined to be failed. You may find it helpful to make a checklist of the tests that you make to help in remembering the results and to reduce any head scratching confusion.

Ted1956 #468632 04/03/22 01:25 PM
Joined: Oct 2021
Posts: 39
Ted1956 Offline OP
Shade Tree Mechanic
OP Offline
Shade Tree Mechanic
Joined: Oct 2021
Posts: 39
Yes the ammeter reads -10 even when the battery is disconnected. It appears to be wired correctly having looked at the wiring schematic. I have ordered a replacement gauge but that was ten days ago and no receipt which is troubling. Assuming it's either a defective gauge or the generator isn't charging. With the horrible weather here in Illinois I haven't driven the car enough to know if the battery is being charged. I have a tender on it in storage currently. The car is a new acquisition so haven't had a road experience with it as of yet.


TedG
Ted1956 #468635 04/03/22 03:06 PM
Joined: Apr 2010
Posts: 734
Likes: 14
Oil Can Mechanic
Offline
Oil Can Mechanic
Joined: Apr 2010
Posts: 734
Likes: 14
Hello Ted1956,
Check the battery's voltage without the battery tender connected, by using a DC volt meter (on a DC volt setting higher than the voltage of your battery) and read the voltage at the battery. Start your engine and read the voltage at the battery. You may need to rev the engine above idle speed some. If the voltage reading is more than the batteries static voltage, than your system is charging and your ammeter normally should indicate within the + pos side of the gauge. If there is no charging voltage reading, then the charging system needs attention. This is where my knowledge of the system falls off. What caused the ammeter to go and stay at the neg -10 indication? Will it happen again to a new ammeter? Don't know. But, doing these checks/tests can help to troubleshoot the charging and indicating systems. By the way, (BTW) you did say you have a generator and not an alternator, correct?

Ted1956 #468640 04/03/22 04:16 PM
Joined: Oct 2021
Posts: 39
Ted1956 Offline OP
Shade Tree Mechanic
OP Offline
Shade Tree Mechanic
Joined: Oct 2021
Posts: 39
It is the original style generator currently. Will follow the suggestion to disconnect the tender and check battery voltage and again running with an engine rev. Ammeter is pegged and frozen at the -10 reading both while idle and running. No change of reading when I apply headlights or horn. Once new gauge arrives I am apprehensive about the install since a reason must have existed to cook the old one. Unless it just retired from old age?


TedG
Ted1956 #468644 04/03/22 04:37 PM
Joined: Apr 2010
Posts: 734
Likes: 14
Oil Can Mechanic
Offline
Oil Can Mechanic
Joined: Apr 2010
Posts: 734
Likes: 14
Hello Ted1956,
I was incorrect (wrong), back in the distant past, when I could not remember what polarity to hook up my battery to the 31 Coach. Well, thinking that ALL the old vehicles were positive ground back then before my time. To my shocking outcome it looked like an arc weld as I tried to make the connection. That was a quick learn. I mention this only to call attention to a possible reason an ammeter would bury itself max discharge. Don't know if reverse polarity would do this but it's worth thinking about.

Ted1956 #468646 04/03/22 05:01 PM
Joined: Oct 2021
Posts: 39
Ted1956 Offline OP
Shade Tree Mechanic
OP Offline
Shade Tree Mechanic
Joined: Oct 2021
Posts: 39
Nice catch! The car had been sitting idle for 12 years prior to my purchase. Seller installed a new battery and very possible he did reverse the polarity for the battery since he was not a car guy. He may have initially installed incorrectly and cooked the ammeter.


TedG
Ted1956 #468654 04/03/22 08:31 PM
Joined: Mar 2009
Posts: 885
ChatMaster - 750
Offline
ChatMaster - 750
Joined: Mar 2009
Posts: 885
Hello Ted --

My experience is that the amp guage, if working at all will work with either pos or neg ground. The only difference is that with pos ground vs neg ground is that the guage reads plus when reving eng with neg ground and minus when reving with pos ground. That is how I check the electrical system on my 48 Plymouth. Just switch the cables to neg ground and pos cable to starter, than after checking electrical system I go back to pos to ground and neg to starter. The rest of the electrical system doesn't care if its neg or pos ground. Hope I made some sense here and best to ya.

Jim.

Ted1956 #468677 04/04/22 09:24 AM
Joined: Apr 2010
Posts: 734
Likes: 14
Oil Can Mechanic
Offline
Oil Can Mechanic
Joined: Apr 2010
Posts: 734
Likes: 14
Hello Ted1956,
Trying to look ahead when you are testing your charging system for proper operation after the new ammeter is installed. I do not know if you are familiar with the need to polarize the voltage regulator and generator with each other or not. You may or may not yet have any of the recommended manuals for your vehicle to reference. Just in case, I'll recommend that you ask the computer "why you need to polarize regulator and generator" and then understanding why, then ask the computer "moss polarizing regulator and generator videos". They are not lengthy videos so I suggest starting them at the beginnings. Just trying to save you from condemning the charging system as broken when maybe it's only a polarization issue. I offer these suggestions because you said that you are new to this vehicle and maybe not that familiar.

Ted1956 #468702 04/04/22 05:27 PM
Joined: Oct 2021
Posts: 39
Ted1956 Offline OP
Shade Tree Mechanic
OP Offline
Shade Tree Mechanic
Joined: Oct 2021
Posts: 39
New question is this. Now have the new ammeter replacement but concerned I might damage it if installed incorrectly. I understand the need to polarize the generator with a regulator but told my 31 Chevy has a cut off switch and no regulator. What then? The cut off has been tested okay.


TedG
Ted1956 #468703 04/04/22 06:43 PM
Joined: Apr 2010
Posts: 734
Likes: 14
Oil Can Mechanic
Offline
Oil Can Mechanic
Joined: Apr 2010
Posts: 734
Likes: 14
Hello Ted1956,
I'd say that you volt meter the battery at static and then with the engine running to verify if the generator is putting out a charge. If not, polarize the generator and see if it charges with engine running. I would think that your ammeter wiring is installed correctly. Look closely at the old ammeter's connections to compare with the wiring diagram. It should be OK to install the new ammeter but make sure that you disconnect the battery before doing it for safety. Once installed, run the engine and retest for battery charging and repolarize generator if needed. Verify ammeter for proper indication.

Ted1956 #468707 04/04/22 08:40 PM
Joined: Oct 2021
Posts: 39
Ted1956 Offline OP
Shade Tree Mechanic
OP Offline
Shade Tree Mechanic
Joined: Oct 2021
Posts: 39
Appreciate the assist. Will address it once again this coming weekend. Will share the ultimate outcome!


TedG
Ted1956 #468878 04/11/22 12:13 PM
Joined: Oct 2021
Posts: 39
Ted1956 Offline OP
Shade Tree Mechanic
OP Offline
Shade Tree Mechanic
Joined: Oct 2021
Posts: 39
Changed out both the cut out and ammeter gauge this weekend. Replacement meter functions correctly. In the off position it's now centered at zero. The battery has a tender so assume it is full charge. On the road the new gauge shows +10 amps. It will dip when headlights are on or horn engaged. Is all good to go or need I tone down the generator brush?


TedG
Ted1956 #468880 04/11/22 12:22 PM
Joined: Nov 2001
Posts: 19,757
Likes: 62
ChatMaster - 15,000
Offline
ChatMaster - 15,000
Joined: Nov 2001
Posts: 19,757
Likes: 62
10 amps is okay but at the high end of OKAY. 12 amps is DANGER of overheating and throwing solder off armature. I set mine as low as I can so I don't boil water from battery on longer trips. It makes up normal starting loss in a few miles or less. Also don't drive at night. If I do resetting third brush in quick and easy.


How Sweet the roar of a Chevy four!
Ted1956 #468883 04/11/22 12:58 PM
Joined: Dec 2007
Posts: 4,023
Likes: 99
ChatMaster - 4,000
Offline
ChatMaster - 4,000
Joined: Dec 2007
Posts: 4,023
Likes: 99
I would follow Chipper's guidance.

Remember that in a third brush generator the output is constant regardless of load on the electrical system. The amperage output is determined by the offset between the fixed brush and the third brush. There is no active voltage or current regulation.

Your generator is putting out 10 amps whether the car needs it or not. The ammeter reading drops when you turn on the lights or blow the horn because a portion of the 10 amps is being directed to that function rather than the battery.

I agree with Chipper that unless you plan to drive a lot at night and use the headlights you should consider reducing the charge rate. The lower load lets the generator run cooler and as he noted, is easier on the battery.


Rusty

VCCA #44680
Ted1956 #469789 05/15/22 07:07 AM
Joined: Feb 2022
Posts: 112
Likes: 2
Shade Tree Mechanic
Offline
Shade Tree Mechanic
Joined: Feb 2022
Posts: 112
Likes: 2
End result is the ammeter itself had been stuck. Replaced it with a new one and it went into action. Took the old unit to the work bench and touched the back side with a probe and the needle popped free! Just my luck having just spent $60 on the replacement gauge. At least now I have a spare for the next owner down the road.

Ted1956 #469793 05/15/22 08:48 AM
Joined: Nov 2001
Posts: 19,757
Likes: 62
ChatMaster - 15,000
Offline
ChatMaster - 15,000
Joined: Nov 2001
Posts: 19,757
Likes: 62
Just remember if it stuck once, it likely will stick again.


How Sweet the roar of a Chevy four!
Ted1956 #469796 05/15/22 09:13 AM
Joined: Feb 2022
Posts: 112
Likes: 2
Shade Tree Mechanic
Offline
Shade Tree Mechanic
Joined: Feb 2022
Posts: 112
Likes: 2
Good point. Fortunately its the new one currently installed.

Ted1956 #469797 05/15/22 11:02 AM
Joined: Nov 2001
Posts: 19,757
Likes: 62
ChatMaster - 15,000
Offline
ChatMaster - 15,000
Joined: Nov 2001
Posts: 19,757
Likes: 62
Let the next guy worry about it? Naw, he won't know it might stick. Problem solved!?


How Sweet the roar of a Chevy four!

Link Copied to Clipboard
Support The VCCA!

Enjoy the forum? Become a VCCA member! The World's Best Chevrolet and GMC Club!


Member Photos
1964 Chevrolet Impala SS
1964 Chevrolet Impala SS
by DreamChevy, February 17
My 1933 Chevy 2 Dr. Sedan
My 1933 Chevy 2 Dr. Sedan
by 1939Chevy1, November 24
Back on the road 79 years later
2 1927 Chevrolet Trucks
2 1927 Chevrolet Trucks
by 1927TRUCKS, June 7
Who's Online Now
3 members (Peter_Gariepy, BearsFan315, Henrys37), 91 guests, and 14 robots.
Key: Admin, Global Mod, Mod
Newest Members
NeilA, Jayhicks, Tomvanhouten, Dads29Chevy, Tractorman
18,308 Registered Users
Today's Birthdays
SabrinaKarras, Speedy1
Forum Statistics
Forums58
Topics59,071
Posts429,078
Members18,308
Most Online1,133
Jan 22nd, 2020
 

Notice: Any comments posted herein do not necessarily reflect the official position of the VCCA.

Powered by UBB.threads™ PHP Forum Software 7.7.5