I drive a 48 3100. It has around a 60 235 with hydraulic lifters. It has been rebuilt with a full flow filtration. I have had a problem with the charging system. It is 6 volts. I have the 216 flywheel, starter, and 6 volt generator/regulator. Today, I put a voltmeter on the battery, generator, and regulator. The battery was charged at 6 volts. I started the truck and increased the rpms. Voltage decreased to 5.8 volts. While the truck was running I checked the generator. A side showed about 6 and the f post was lower. At the generator it was the same. I went back to the battery, it showed 5.8 volts with no difference if I increased the rpms. Any ideas or suggestions? Thanks
Charging Woes O.K. ; Basic testing time ~ you'll need : Volt meter with at least a 20 VDC scale . Several test leads with alligator clips on both ends . Test light with alligator clip on one end and sharp point on the other , you can use any old 12 volt bulb in a lamp socket for this , just add two 4' long wires with alligator clips on each end . Disconnect the ground cable before touching the wires each time . Disconnect the generator wires , re connect the battery and start the engine , connect your voltmeter to the " GEN " , " ARM " or "+" terminal of the generator , the other meter lead to a known good ground ~ I always use the carby . You may see some voltage , slightly Rev. the engine while watching the voltmeter ~ if it begins to rise , SLOW DOWN before it passes 8 volts or you'll fry the generator . No voltage ? is the needle maybe trying to go backwards ? this indicates either you have the meter's leads reversed or the generator is reverse polarity , uncommon but it happens . Still no voltage ? engine idling , meter connected to the generator , connect a test lead between the two generator terminals and s l o w l y Rev. the engine , it should rapidly begin to rise and show over 8 VDC . Still no voltage ? DO NOT mindlessly over rev the engine trying to make it charge ! . connect a test lead from a hot voltage point like the battery or "+" terminal of the regulator and touch it to the generator terminal , this will make the meter show voltage unless it's (the meter) not connected properly . if it shows voltage , slowly Rev. the engine to see if the voltage rises ~ if so , the generator appears to be O.K. . Your next test should be to disconnect the wires at the voltage regulator and test thhem with your test light and the truck's battery voltage to ascertain they're properly connected ~ the thicker one connects between the generator's Armature and the " Gen " terminal on the voltage regulator and NOWHERE ELSE ~ not grounded if both ends are loose , no power either . The thinner wire connects between the generator's field terminal and the " FLD" terminal on the regulator , again NO WHERE ELSE and has NO ground nor power connectivity . All good ? . Occasionally there's a third wire between the regulator and generator for ground , you'll see the threaded hole in the generator for this , use a short screw as too long a screw will damage the internals of the generator . If still no charge the voltage regulator is prolly faulty , of the cover has screws you can disconnect the battery's ground cable and remove the cover , use some lint free stiff white paper (think unused business card) between the contacts inside it ~ draw the clean paper through and you'll see some black crud on the paper ~ repeat using clean paper until it comes out clean . I hope this helps , it sounds difficult but isn't once you try it .
Once again, Nate has the detailed instructions needed to accurately troubleshoot the problem and find resolution. No surprise, but always impressive, Nate.
Hello Nate, well I have been driving around now for a few months (thanks to your help on previous issues)...Well, I suspected I have a problem with the charging system. Didn't really notice since I had a battery tender on and kept the Battery well charged. However, lately I took the tender off , forgetting to put it back on and noticed after I take the Truck out for a spin a couple times a week, it would get harder to start the truck.. Then yesterday, I took the Truck to the car wash and bam, wouldn't turn over. Got my portable charger out and started right up.. Took the truck around for one hour, turned it off, and Truck wouldn't start back up. So, I had the battery tested and it is fine.. So it leads me to think the Generator or the Regulator is my issue. I noticed you had a nice write up on a testing procedure and will go over it this week, but if you don't mind I have some questions (forgive me, if they might be a little stupid, but Just want to make sure I understand.) Btw, my system is 12v, but I assume this procedure works just the same. Anyway, I have gone down your testing procedure, and below I have some questions, which I mark in red: Basic testing time ~ you'll need : Volt meter with at least a 20 VDC scale . Several test leads with alligator clips on both ends . Test light with alligator clip on one end and sharp point on the other , you can use any old 12 volt bulb in a lamp socket for this , just add two 4' long wires with alligator clips on each end . Disconnect the ground cable before touching the wires each time . (I am assuming you mean to disconnect the "-" terminal on the battery?) Disconnect the generator wires , re connect the battery and start the engine , connect your voltmeter to the " GEN " , " ARM " or "+" terminal of the generator , the other meter lead to a known good ground ~ I always use the carby . (Is the "Gen" the side where the FLD wire is connected and heads up to the Regulator?) You may see some voltage , slightly Rev. the engine while watching the voltmeter ~ if it begins to rise , SLOW DOWN before it passes 8 volts or you'll fry the generator (In the last step, you say to disconnect the Generator wires, how would the generator be damaged during this test, since no wires are heading up to the Regulator? Also, if my system is 12v, I assume the threshold is different ) No voltage ? is the needle maybe trying to go backwards ? this indicates either you have the meter's leads reversed or the generator is reverse polarity , uncommon but it happens . Still no voltage ? engine idling , meter connected to the generator , connect a test lead between the two generator terminals and s l o w l y Rev. the engine , it should rapidly begin to rise and show over 8 VDC .( When you say connect the meter to the generator, does it matter which terminal I connect to? Either the "Arm" or the "Field". Also, I assume, that I leave everything else connected. Field wire,and ARM wire still connect to the Regulator. Still no voltage ? DO NOT mindlessly over rev the engine trying to make it charge ! . connect a test lead from a hot voltage point like the battery or "+" terminal of the regulator and touch it to the generator terminal , this will make the meter show voltage unless it's (the meter) not connected properly . if it shows voltage , slowly Rev. the engine to see if the voltage rises ~ if so , the generator appears to be O.K. . (I assume the Generator wires need to be reconnected in order for this test to work?) Your next test should be to disconnect the wires at the voltage regulator and test thhem with your test light and the truck's battery voltage to ascertain they're properly connected ~ the thicker one connects between the generator's Armature and the " Gen " terminal on the voltage regulator and NOWHERE ELSE ~ not grounded if both ends are loose , no power either . ((So I am clear, I should disconnect the 2 wires, ARM,and FLD at the Regulator. Testing each wire, ONE at a time to see if my test light goes on.. For Example, I clip one end to the ARM wire, and touching the test light to ground? T2nd wire, "FLD", I clip on and then touch test light to ground. I wonder when I test GEN and FLD, Anyway, forgive me is these seem like stupid questions, but just wanted to over over this before I start testing. Thanks again Nate!)
The generator can (should) have residual magnetisim sufficient to cause it to begin charging and speeding it up will cause it to over heat and melt the solder connecting the armature wires to the commutator bars, you don't want to try and find anyone who will re solder them, once this happens the generator is truly kaput . Yes, always disconnect the ground cable begore touching any of the other wires, your truck is most likely a negative ("-") ground but some are positive ground . The wires on the generator are different, 'Gen.' 'Arm.' are the same. 'Fld.' is different and they ust not be reversed . The Gen./Arm. terminal _always_ has the thicker of the two wires . Mark (tape) or photograph the regulator wire connections then remove them (battery ground cable disconnected and tucked down behind the battery where it cannot possibly touch to battery post or you'll soon understand why I yammer on endlessly abput this) and gently & carefully wire brush the posts on the regulator that the wires attach to, there's almost always stamped in abreviations that match the terminals on the generator . A thought : ? have you yet connected a volt meter to the battery terminals when the engine is running with all lights, heater, radio etc, turned off to see what the charge voltage is ? . If it's over 13.5 VDC when you rev. the engine a little bit, no need to test the generator, it's working . Sorry if all this is confuddling, I too had to learn it and was befuddled for some time .
I have connected a volt meter and it register around 12, but when I rev. it doesn't change. I actually did pull the neg. cable from the battery when the engine was running and the truck died.
Okey Doke then : Take your time and do the generator test as described, see what happens and report back . For a really quick test , remove the generator wires and fan belt & connect 12 volts directly to the two generator terminals ~ it should spin like an electric motor, if not it may just need cleaning, new brushes and lubrication of the bearings. Attached is a picture of "Zoom Spout" electric motor oil ~ it has an extendable narrow spout to easily get the oil where it needs to go , only three drops in each bearing will do the job , mind the prie ! i only paid 7 delivered on Amazon, some wanted $15 ! .
Okay, First test (Meter Connected to Gen/Arm with other meter lead to ground). Result: Meter reads just over 1 volt.. Rev up slightly goes to about 1.4 to about 2.0. Also took meter to batter and it reads spot on 12v. Sooo doesn't appear that the generator is outputting 12volts. What do you think could cause this? -James
Try the motoring test, if no go take it carefully apart and look at the brushes . I bet they're worn out . NAPA should have new ones, try asking for 1958 Chevy truck generator brushes . The copper bars on the commutator are most likely near black in color, instead of $pending to have it machined, just use a brass bristled wire brush, the all tooth brush size ones sold at almost every .99 cents store . Brush across the bars until they're as clean as they'll get, don't use sandpaper nor your regular big old wire brush . Once it's yellow or bronze colored again, use some starting fluid or brake cleaner to rinse off the crud and dirt, DO NOT use carby cleaner ! . The commutator is designed to be machined once maybe twice then it gets too small in diameter to ever work propelry again so resist the urge to pay money to a shop to ruin it ~ either it's good and needs cleaning or it's kaput and you'll find another . A tiny dab of good quality high temperature disc brake typ short fiber (means NO white or brown bearing grease !) , about the size of a snapped off pencil tip, gently smeared inside the bushing in the commutator end is all that will need . synthetic grease, like boat trailer grease is good if you have that, otherwise buy some Molybium grease, it'll do better in your front wheel bearings and U-Joints so no wasting $ here . Re assemble it and do the motor test, it should (must) spin when powered up, remember to use the same polarity as your truck is . If it spins (not terribly fast BTW) on the bench it will charge so re install it and make sure there's a ground wire between the generator's case and the regulator's base, there likely isn't one now so add one, use black or green wire, no thinner than the ARM/GEN wire, so 10 or 12 gauge . If you can, solder the ring terminals to both ends of the ground wire, it makes a difference and do not use a long screw in the generator's casing ! . Whilst you're adding the ground wire, look closely at the ends of the current generator harness ~ if there are broken strands of wire at the terminals, this needs to be addressed, finding the proper 10 guage wire these days can be tricky, I save old Imported car wiring harnesses and cut the good wires I need out of the middle of the old harness and discard the ends . makes it work properly (charging current is critical) and looks nicer too when you're all done . If it motors and you add a ground wire and still doesn't seem to charge when you fire it up, STOP ! don't try to "polarize" it as this typ of generator is self polarizing and you can easily fry it and the regulator in about .05 second . O.K. ? . don't panic/worry, you're willing to do this so take your time and be careful and methodical ~ once you get it going again you'll have BIG TIME bragging rights down to the coffee shop, show & shine etc. as most think what you're learning now is some sort of voodoo . ? Can you post pictures ? . ask any child how this is done, I finally figured it out a while back and wrote a thread about it, IIRC others chimed in to explain it better .
Excellent Nate, I just had a little time this evening to do the first test. I will do the motor test tomorrow night... One question, you mention , "Re assemble it and do the motor test, it should (must) spin when powered up, remember to use the same polarity as your truck is ." Can you explain what you mean by the same polarity as the truck, are you referring to how I connect the + and - terminals to the generator? I plan to bring out the Truck Battery and then connect the NEGATIVE (Truck Ground) to the Field Terminal post on the generator, and the POSITIVE to the GEN/ARM post on the Generator. I would think the polarity wouldn't matter which terminal got the - or + since it would just spin in either direction.. Perhaps I am not understanding, but thought I would ask before I hook up the Battery to do the motor test. I will send pics tomorrow night.. Thanks again, James
Okay, I just did the motor test (Connected the 12v battery, + on ARM and - on FlD), and Nothing... Here are some photos I shot:
Well ; Yes, I meant mind the polarity, you have a Chevy so negative ground meaning the - should have been connected to the generator's case..... It's important because the generator retains a little bit of residual magnitisim so when you connect it, if the polarity has been reversed the contact points in the regulator will likely chatter / buzz / burn due to it trying to fight the reverse polarity . I can see the commutator bars are dead black so maybe a careful cleaning of the commutator bars as I described above will set things right again, the brushes don't look too worn to work . Give that a try and see how it goes unless you're tired of fooling with it, I never tire of hands on working and tinkering , it keeps your mind fresh . Sorry about the slow response, one of my vintage Motos has been having an odd hot starting problem so I spent a bit of yesterday on the carby then decided to remove the wheels and clean out the accumulated brake dust and grease, cleaned an lubed then properly adjusted the manual brake linkages,cams, cables and so on, it now starts one kick in 45* F temps, a good thing as the choke flapper in the carby broke off (old age I think) , the brakes once again work as they did in 1970 when it was new ~ if you cannot easily lock up both brakes, you cannot possibly modulate them in traffic or riding on snow, ice, wet greasy pavements etc., etc...... I had a nice brisk pre dawn ride to the Coffee Shop before sunup . Keep us/me posted, we'll get this sorted out , O.K. ? .
Not a problem..Funny how we get to try to work on one thing then get distracted and start opening up another can of worms. In the end it is all fun! I did go ahead an pull the generator to have a look at it on my bench.. Sounds like I did the motor test incorrectly.. I will reattach a 12v battery and put the "+" on the ARM and then the "-" on the case.. Then see what happens. I did notice there is a lot of dust and crud in the case, so I might try to clean it out as best that I can and then do as you say and take a brass wire brush to the commutator bars. I will give it another go tonight! Thanks, James
O.K. James ; Like I said, sometimes the copper commutator bars just get dirty over the years . I looked up a rebuilt one and it's not too much $ : ACDELCO 3341007 {#19133825} Professional; Remanufactured Info GEN; Unit Mfr: ACDelco; Amps: 30; W/O Pulley; External Fan; External Regulator; Clock: 12:00 $65.79 $8.00 $73.79 Add to Cart Or, if you're a Junkyard Junkie like me (no feeling like fixing it your ownself) here's the wide variety of vehicles it fits to help you find one used : Please refer to catalog for application details. AMERICAN MOTORS AMERICAN 1958-1962 AMERICAN MOTORS CLASSIC 1961-1962 AMERICAN MOTORS CUSTOM 1961-1962 AMERICAN MOTORS DELUXE 1961-1962 AMERICAN MOTORS SUPER SIX 1961-1962 BUICK CENTURY 1954-1956 BUICK ELECTRA 1959-1961 BUICK INVICTA 1959-1961 BUICK LESABRE 1959-1962 BUICK SKYLARK 1954 CADILLAC DEVILLE 1959-1963 CADILLAC ELDORADO 1957-1963 CADILLAC SERIES 60 FLEETWOOD 1953-1963 CADILLAC SERIES 62 1953-1963 CADILLAC SERIES 70 ELDORADO 1958 CADILLAC SERIES 75 FLEETWOOD 1953-1963 CHEVROLET BEL AIR 1958-1962 CHEVROLET BISCAYNE 1958-1962 CHEVROLET C10 PANEL 1960-1962 CHEVROLET C10 PICKUP 1960-1962 CHEVROLET C20 PICKUP 1960-1962 CHEVROLET C30 PANEL 1960-1962 CHEVROLET C30 PICKUP 1960-1962 CHEVROLET CHEVY II 1962 CHEVROLET DEL RAY 1958 CHEVROLET IMPALA 1958-1962 CHEVROLET K10 PICKUP 1960-1962 CHEVROLET K20 PICKUP 1960-1962 CHEVROLET P10 SERIES 1960-1962 CHEVROLET P20 SERIES 1960-1962 CHEVROLET P30 SERIES 1960-1962 CHEVROLET SUBURBAN 1960-1962 CHEVROLET TRUCK 1955-1958 GMC 1000 SERIES 1961-1962 GMC 1500 SERIES 1961-1962 GMC 2500 SERIES 1961-1962 GMC TRUCK 1955-1960 OLDSMOBILE 98 1958-1960 OLDSMOBILE DYNAMIC 1958-1960 OLDSMOBILE FIESTA 1958-1960 OLDSMOBILE SUPER 88 1958-1960 PONTIAC BONNEVILLE 1958-1962 PONTIAC CATALINA 1958-1962 PONTIAC CHIEFTAIN 1958 PONTIAC GRAND PRIX 1962 PONTIAC STAR CHIEF 1958-1961 PONTIAC VENTURA 1960-1961 STUDEBAKER COMMANDER 1956-1958 STUDEBAKER GOLDEN HAWK 1957-1958 STUDEBAKER LARK 1959 STUDEBAKER POWER HAWK 1956 STUDEBAKER PRESIDENT 1956-1958 STUDEBAKER SILVER HAWK 1957-1959 STUDEBAKER SKY HAWK 1956
That isn't a bad price at all... Btw, you mentioned connecting a ground wire to the case.. I noticed my old Gen, just had the screw hole, but no screw, nor ground wire. Where does your ground wire connect up to from the generator? James
James ; look at post # 12 . The ground wire reaches from the generator's case to the base of the regulator ~ _not_ the rubber insulated mounts, the base proper . If you dismount the regulator and look at it, often there is a tab or hole for this purpose . Failing that you can use one of the cover screws but it'll look bad to me . Proper grounding is critical and where the battery ground strap (correct0 or cable (wrong but will suffice) is critical to starting, accuracy of the gauges, battery, generator and starter life, brightness of every light in the entire truck, etc., etc...... As long as you're fired up to fix this and fix it right, look at the battery cables (or post clear pictures of them), they must be 0 or 1 gauge no thinner and the ground *MUST* be bolted to the engine or tranny, NEVER the frame nor body . NAPA (and prolly many others) will have the correct gauge cables new, measure your old ones from end center to end center and maybe add length as most have been replaced with off the shelf crappy ones that are either too short or too long and almost always to thin gauge ~ typically 4 gauge . Of course, if you have those repair a cable add on clamps, whatever you have is worthless, either get a new solder on typ of battery clamp and have the weld shop attach it to your old cable or buy new cables, your truck will thank you .
Those rubber insulated mounts have dried and flaked away over the years on the regulator. I just had a look and only 1 of the 2 screws still have that rubber left. By the way, I found the ground screw hole on the regulator. Clear has day and has a nice GRD stamped into the right side. Never noticed it before!
