1947 6 volt starter issue

[Jamdadbay]

Hi team

My new-to-me buick sat for 35 years before I picked her up. While working on my engine (original straight 😎 I was using 12 to turn it over and the starter worked fine, and ultimately the engine now runs. But now I've got the 6 volt battery, it just doesn't have enough ooomph to turn it over. It tries, but only just turns the cream very slowly. I know the starter works, I know the engine works. It was all original, including the starter so I assume it's all 6 volt. What am I missing? 

[37_Roadmaster_C]

Typical 6 volt starters turn the engine slowly. If you used 12 volts, it will turn the motor over at least twice as fast and possibly more. This is just the way it is. Check all cable connections and make sure they are all clean and tight. Do not forget the ground cable and any bonding cables between the frame and the motor block. If you have replaced either or both of the battery cables the regular parts house cables are way to small as they are for modern 12 volt systems. Having cables made by a GOOD battery store or doing it yourself using 2/0 or bigger welding cable will make a huge difference. The old 6 volt starting systems seem wrong when compared to modern 12 volt systems, but with a well tuned car they were very reliable.

Edited November 19, 2020 by 37_Roadmaster_C
Spelling (see edit history)

[Bloo]

You need 6v cables if you don't have them. The wire is bigger. 00 gauge is about right. A local supplier of tractor parts should have them, or make some up out of 00 welding cable.

 

The starter bushings could be worn and letting the armature drag. The brushes might be worn out. Compare their length to new ones, but unless they are 2/3 gone or more, look elsewhere for the problem. Look at your commutator. Someone may have undercut it. You do that to generators, but not starters. If someone did, copper from the brushes will fill the grooves between the copper segments and cause the starter to draw way too much current. Look for this when you look at the brushes.

 

The copper bolts in the solenoid could be shot. Check them for extreme wear. Also ohm test both solenoid windings. One goes from the small terminal to ground, the other from the small terminal to the large bolt that is connected to the starter motor. You'll need to disconnect the link down to the starter motor in order to check. A bad winding can cause your symptom.

 

Many Buick starter solenoids of this era have threads to adjust how far the solenoid pulls the gear out. The shop manual should have the measurement (maybe 1/8" but check the spec). I can't swear to it but I think if this adjustment was off it could prevent the solenoid from making good contact.

 

Edited November 14, 2020 by Bloo (see edit history)

[Ben Bruce aka First Born]

I agree with the cable probably being a factor. ALMOST always. The 2 /00 [ 2 aught] will be as big as your thumb , or larger.  If the cables are about the size of your little finger, or smaller, do this first.

 

  Ben

[Jamdadbay]

37 roadmaster, Bloo and Ben... Thanks for the advice guys.... Really great ideas. I've got the right thickness wires for the minor wiring to solenoid, switch, coil etc but I haven't changed up the main battery to starter cables. Again... I really appreciate the feedback guys. Love this forum 👍

[Ben Bruce aka First Born]

How about pictures of the starter/battery area.   Entire car would be nice. We LIKE pictures

 

  Ben

[old-tank]

6 v batteries take a long time to charge.  Put it on a charger over night.

[Dan O]

You can order proper reproduction cables online from Bob's Automobilia if you cannot make them yourself.  I agree that a working 6 volt starter will turn the engine with no problem if the battery is fully charged and cables are the right size.

[Matt Harwood]

We should put a sticky post at the top of every forum with a permanent link to one of these "6V is hard to start" threads. The hard start issue comes up at least twice a week, nobody uses the search function, and the answer is almost always the same: get bigger battery cables, clean all your ground points, add a ground cable between the battery and the starter, make sure your battery is healthy and fully charged, and maybe add an electric fuel pump for priming and hot weather.

[60FlatTop]

Is your timing correct? A little too much advance will make her grunt. Check the flyweights, breaker plate, and initial setting.

[buick man]

See if you can get ahold of another known good 6 volt battery and connect it to your existing 6 volt battery in parallel.  Positive to positive & Negative to negative.  This will keep you at 6 volts but will double your amp hours ( capacity cold cranking amps ) .  This old shop technique helps to eat through any bushing, windings or brushes resistances ... Jus a thought.  

 

Edit :  Oh and this connection technique also helps when you are attempting to charge a tired battery and just can't seem to get pass the resistance of the tired battery. Hook a good known battery of the same voltage in parallel and hook the charger + & - to the good battery terminals then use jumper cables to connect in parallel to the tired battery.  This method will allow the tired battery to overcome charge plate resistance and begin to charge after a spell on the charging bench ... 

 

Edited November 25, 2020 by buick man (see edit history)

[critterpainter]

In my experience cheap 6V batteries don't start Buicks.     I have found that the Optima 6V battery does a good job of starting a hot Buick engine (and a hot suborn 312 Ford engine).       Also John Deere has (or used to) a long narrow 6V battery that was used in some of their 12V diesel tractors.

[buick man]

Back in the late 60's I had a 1950 Dodge Wayfair , bought it off the back side of a used car lot and it had a moderate main barring knock ... paid 35 dollars.  All was good until come winter what with the degrees dropping and snowing it just did not wanna fire up and would barely crank.  Went over to the public bus garage and asked if they had any used 6 volt bus batteries.  Got a big ultra heavy long bus battery that had a kazillion plates and uber cranking amps and installed that into the Dodge.  Man would it ever crank but the tired old Dodge would still not fire up.  With that battery I could crank it so long that the oil pressure would rise to about 40 lbs but still no fire up starting.  Had to ultimately take it into a heated garage to get it going.  On hind sight should of pulled the starter and rebuilt it because it no doubt was tired as well and dragging and crap for compression but then I was in high school and had little more than just pocket change to spend.