Running 12-volts through a 6-volt starter

Ran into a problem this weekend. Could use some feedback.

I realize running 12-volts through a 6-volt starter is not ideal. There will be long term effects and ultimately the thermal load will be higher. Yes, yes... I'm aware of this and a lot more. I'm also aware that they can be rewound and this is an even better idea, and it's something I'm having quoted right now.

My questions though...

This weekend I had a freshly rebuilt, 6-volt starter take a dump on me. I only bumped the engine a few times with it while I was doing some work on it. (331 Chrysler, fresh rebuild, plugs were out, turns easy by hand) Went back to bump it again and nothing! Zero! Zip! Nada! I pulled it off and we tested it every which way we could possibly think of and everything seemed to have failed. Solenoid would not pull the plunger in, the motor itself would not even turn over. Mechanically everything is free, but no go on all accounts. And yes, it was tested with 12-volts.

I'm having a hard time believing that just a few bumps of the starter with 12-volts would fry this starter. Has anyone else experienced something like this?

We tested another starter that was being canibalized for parts and found the same problem.

The place that built it is going to fix it, no questions asked, but if this is going to happen every time, I need to find an alternative solution.

Any experiences you can share on running 6-volt starters on 12-volts would be appreciated.

Thanks!

 

i just made the switch to a 12v system last week. the starter sounds like it's getting lot more juice. but has been working fine. not to say that it always will, but for now it's not fried.

 

I ran 12 volts on my 6 volt Jeep starter for several years with no problems. Starter was original non-rebuilt, I never did a thing to it.

 

Ran a 6 volt on my Flathead for years. More than enough power!

 

A 6-volt starter will work just fine with 12-volts. I have 12 volts in my 50 Ford and 53 Ford, both with flatheads and also in my 53 Stude coupe and 49 Stude truck. All still have the 6 volt starter, for many, many years. I also ran 6 volt starter in most of my VW's with 12 volts. The only thing that may have happened is that the starter gear went too deep into the flywheel, happens once and a while, that is why i carry a dead blow hammer. If you kept on trying to start it with it jammed up, it will fry the starter. ^ volt systems actually can carry more of a load that 12 volt.

 

I switched my Ford to 12v over two years ago and still running the 6 starter.

 

Alot of the replacement parts for starters, alternators and the like are cheap ass junk.....try to find some NOS or eqiv. stuff......I used 12v on 6v starters with no prob at all.....motor always fired quickly, didn't have to crank it alot

 

There's something wrong, it was common trick at one point to run 12v through a 6v Ford flathead starter. A few bumps should not kill a starter.

Box it up and send it to Clarence (while he's still alive and in business). He'll fix it and convert it to 12v for you.

 

Starter on 12v should have no problems. In fact, in my vw days, I'd run a 6v starter on a high torque engine just cause it would fire up quickly.

What you need to worry about voltage reduction on is change out your light bulbs to 12v, and get a voltage reducer for your wiper motor.

 

Now THIS has my attention! Hmmmm.... I wonder if THIS could have caused it. I noticed that everytime I bumped it, it sounded a little strange. I didn't think to even check if the plunger was withdrawing properly. I also noticed when I was doing a mock up of the starter that things looked pretty tight, but figured after I had everything buttoned up correctly and tightened down it would sit right against the bellhousing.

You have me thinking. The other starter motor came off an engine that had a broken rod, so if the engine jammed and someone would have tried to start it it may have burnt out that starter as well. Hmmmm....

Based on replies here, you've confirmed that it's not a big deal to run it on 12 volts. So maybe the starter is trully just getting stuck. It's a new flywheel (146 tooth) and the matching stock starter. The mounting position has not changed at all (and can't), so it seems like it should be fine. Any preventative measures I can take to keep it from jamming? More grease?

Thanks for the quick replies, everyone!

 

Dunno about more grease, but i would try not to crank and crank. I usually give it a quick turn, set up so it fires right off. I think that as more current is applied and the inertia of the flywheel can drive the bendix gear out farther that it should. But then again, i fix it with a hammer, so I may not be the expert...lol

 

When you run 12v on a 6v starter the voltage drops down to about 8v. You should have no problems as long as you don't crank the engines over for long periods of time or try moving the car in gear with the starter.

 

I haven't turned the engine anymore than about 10 or 15 degrees with it. Literally just bumping it. Bumping it three turns probably didn't even give me a half revolution.

 

Fully agree!

 

Will a '56 12v starter fit???

 

Did it still have a 6V solenoid?

 

I ran a 6 volt starter on my boat's 56 354/650 hp for 3 years with no problem. I will say that it would always start in about half a turn. Oh yeah, I must have adjusted the pushrods a half adozen times, trying to get the banks to run the same temp.
I think I finally took 1 temp gage out.

 

All I can say Is what I know from my own experience. I put my '55 Firefilite in a garage to keep it out of the weather, then started it up every couple of months. The 6-V starter would WHIRL over & start the 291 quickly.

BUT, I'd get my ass out of the driver's seat ASAP and disocnnect the ground. That way, I didn't think I was over-taxing the 6-V starter. No probs.

 

I dont know how your perticular starter operates but my 235 chevy starter is 6 volts with a 12 volt soleniod from a corvette mounted on top to replace the 6 volt soleniod. from my understanding a 6 volt soleniod will burn up quickly when hooked up to 12 volts and can force the plunger to stick out until something catches on fire or mechanical failure.

 

6 volt starters when used with 6 volts draw alot of amps, so they are wound with very heavy wire compared to a 12 volt starter. When using 12 volts they actually draw half the amperage, so you really can't hurt it. I used to drive my beetle into the garage on the starter, when it wouldn't run which was pretty frequent, it was a 6 volt starter with a 12 volt battery. Must have got a bad one.

 

As many have pointed out I also ran a 12 volt battery in my '49 Olds rocket for starting. It was a regular kit sold in those days and I bought mine to increase starter life. Which it did. Plus starting the car much faster so less cranking time on the starter. Worked great. Many people had them in the late 50s, early 60s.

 

Yo, GreyOne, do you think going with the 12-V solenoid helps? Sorry, tech, Q, buddy.

 

If it's from a Mopar that had a 146 tooth flywhee then yes. There was like one year of 12-volt starters for that model and I believe it was in '56. Might be what you have.

Thanks again for all the great input. I feel much better about all this. I didn't realize how common it was.

I like the question of rather or not a 12-volt solenoid would work. I would think the combination of a 12-volt solenoid mixed with a 6-volt starter motor might be a pretty good combination.

Do later LA style starters interchange with these early starters (51 to 56 or so Mopar, give or take a couple models and years depending on which exact make).

 

I ran a 6volt starter in my stock 38 chevy for years and possibly years before me and it worked great. I dunno what the prob with yours is. Does anything "look" burned out?

 

I don't think so. Basic electrical math says that higher voltage and/or lower resistance will create more current flow. In the scenario you describe above (heavier windings and more voltage) both will contribute to more amperage. The thing is, the higher amperage through the windings creates a stronger magnetic field, that's why the starter spins the same load faster. The current flows through each winding in the armature for just a short time each rotation (the commutator & brushes are a rotary switch), however, there is a constant current in the field windings, and it is definitely higher when you're using 12 volts vs 6.

 

This is also why it generates more heat which could ultimately be a factor for long term damage if care was not taken.

 

Heck when I had to get a car into and later out of a garage that the fuel pump quit on, I bumped the starter with it in gear to get it in and out of there, 6V Chevy starter with a 12V battery on it. I suppose if you tried to use it for the drive in an electric golf cart or something and ran it for long periods on 12V you'd cook it, but even then it would last a while.

 

Yes I think a 12 volt solonoid is the only way to go.

 

That was the reason people went to 12 volts to the starter in the old days. It spun faster and actually started. Instead of grinding along getting hot and burning up. of course if your car still wont start maybe you should look into that. but if you ever tried to start a hot '49 rocket 88 on a hot day with 6 volts you would love the 12 volt conversions. They were done with 2 six volt batteries and a Ford selnoid so that only the starter got 12 volts.

 

My '50 Poncho has been running a 13.6v GM one wire alt and 12v Die Hard battery on all stock everything else for years with no problems. (though I obviously changed the flasher relay, bulbs, and I don't use the blower). A couple months back my car quit starting and I ended up killing off three batteries worth of juice trying to crank it before realizing the fuel pump took a dump. Still works fine, and with it's new fuel pump runs fine as well. I was holding 20 seconds or so attempting to start it off my 12v battery. You shouldn't have to change anything.

It sounds to me like you have some resistance somewhere in this freshly rebuilt motor, perhaps the flywheel or something. You'd have to be drawing a hell of a lot of amps though. It would really take a dead short in the starter to do that in a few bumps IMO.