'40 Slow cranking when starting.....

[mike42]

My '40 cranks real slow when starting it up. I had the battery checked and all is well there.The engine starts right away, but it just turns real slow.

I've cleaned the batt posts also.

Where is the next area I should check regarding this. Starter connections....?

Thx....Mike

[G.M.]

Originally Posted by mike42

My '40 cranks real slow when starting it up. I had the battery checked and all is well there.The engine starts right away, but it just turns real slow.

I've cleaned the batt posts also.

Where is the next area I should check regarding this. Starter connections....?

Thx....Mike

Ground connections and cable size. G.M.

[drolston]

Clean and tighten connections to solenoid and grounds to firewall and engine.
Could be degradation of contacts internal to solenoid, adding resistance. Is the solenoid warm to the touch right after starting? That would be a clue. Also feel the cables near their connections. Sometimes the cables corrode inside their sheathing. Look for green copper corrosion around the cable ends.

[Seth Swoboda]

Check to see if your starter needs rebuilt. The starter will "drag" when it needs rebuilt.

[supereal]

It is likely the end plate bushings are worn to the point that the armature drags on the field pole shoes when the magnetism is applied.

[Steves46]

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Originally Posted by Seth Swoboda

Check to see if your starter needs rebuilt. The starter will "drag" when it needs rebuilt.

I agree. Mine was behaving the same way a few years ago-a rebuild resolved this issue.

[mike42]

Thx very much. Will check all these out.

Mike

[JSeery]

Start with cable size, a 6v system requires a larger cable size than what is normally available in the local automotive shop. If someone change the cables out that would cause the problem. If the cables are correct, then check the grounds. Clean metal to metal contact and grease to keep it that way. If all of that checks out, then most likely a starter issue.

[V12Bill]

If it is 6 volts it will crank slowly. My wifes '06 Nissan cranks over fast with 12 volts. My '39 PU cranks slowly with 6 volts. Nothing wrong with either car. Some waste money converting to 12 volts just to feel good because it will crank like their rice burner. 6 volts cranks our beef and potato cars more deliberately.

[Dave Castle]

Waste money converting to 12 volt ? Not really ! One of the best things you can do to make a vehicle dependable.

[D. Jones]

Originally Posted by Dave Castle

Waste money converting to 12 volt ? Not really ! One of the best things you can do to make a vehicle dependable.

What makes a 12 volt system more reliable than 6 volt? I realize that it takes twice as many amps at 6 volts as it does at 12 to do the same work but I guess I'm too deficient in electrical theory to understand the reliability difference. I'm truly curious.

[tubman]

6 volts is perfectly fine if you keep everything up to snuff. 12 volt systems will tolerate a lack of maintenance a little better than a 6 volt system, but when something does go, that lack of maintenance makes it harder to find and fix the problem.

[JSeery]

Originally Posted by D. Jones

What makes a 12 volt system more reliable than 6 volt? I realize that it takes twice as many amps at 6 volts as it does at 12 to do the same work but I guess I'm too deficient in electrical theory to understand the reliability difference. I'm truly curious.

Higher voltage helps, most aircraft, military vehicles, boats use 24 volt systems. If you double the voltage you cut the amperage in half for the same wattage. Watts (W) divided by Voltage (V) = Amps (A). If a 100w bulb required 16.7 amps at 6v, it only requires 8.3 amps at 12v and 4.2 amps at 24v.

Higher voltage has more reserve in cold weather and more cranking power to the starter.

If you are keeping everything original, the 6v positive ground system works fine. If you start adding and/or changing things there is a lot of advantages to 12v negative ground.

[RalphG]

Just my own experience, my 39 Deluxe (all orignal and unrestored) always cranked fast for a six volt system. Sounded about twice as fast as the 52 Merc and was always a better starter. The Merc is a little better now that I've replaced the ground cable with a heavier one and also a big old tractor battery.

[supereal]

The primary advantage of 12 volts is the reduction in wire size (guage). When vehicles began to add accessories such as air conditioning, etc, the original conductors couldn't handle the load. Recent improvements, such as LED lighting and common bus wiring extend load ability. My '47 is still 6 volts and starts and runs fine, but I had to devise a way to feed the headlights to be safe at night, and design a complicated relay system to operate the convertible top quickly.

[Charlie Stephens]

What was the last thing you changed before the problem started, or has it always been that way?

Charlie Stephens

[Phil Gillespie]

Originally Posted by Charlie Stephens

What was the last thing you changed before the problem started, or has it always been that way?

Charlie Stephens

That is always a good fault finding process. Go back to the last thing you played with. Works for me in many cases.
Phil NZ

[mike42]

Guys.....the only thing that has changed is the starter that I had rebuilt awhile back. I recall that it was turning slow before that though and I just thought it was because it was 6v. Even though it turns slow....it fires right up and runs great. I've had the car for 6 years now and the Owner I bought it from had not tuned it up with new points for 15 years !!! It still fires right up and drives great !!

I haven't been able to do much out in the barn right now as we just had one hell of a Northern Michigan storm that put another 3 feet of snow on the ground ! Have to wait this out in order to get car out the barn.

More later.

Thx....Mike

[deuce_roadster]

This isn't your problem but always remember the amount of energy your battery can supply goes down with the temperature, as it is a chemical reaction.

[big job]

All I can say is they whipped right over when new and for yrs after. However now they
at say 70yrs old expected to do so. You can replace cables till the cows come home,
but as we all should know, these starters have aluminum end plates. Aluminum never
mixed well with steel. Its like removing the big alternator bolt on even a late vehicle that
usually snaps. All corroded up with that white stuff corrosion. These end plates have to
have a good clean ground and if not= no cable will fix that...so one says, gee my buddies 38 6vt pos grd Plymouth (Chevys too) whips over. Thats cause they did not
use aluminum which is not the best conductor next to wood which will conduct if wet.