Battery or starter problem? How do I know/test which it is? Kubota L3940

[over40dq]

Got in my tractor moments ago, and it cranked once then nada. Turned the key, and a rattatatat sound emitted, now no sound at all. The key was NOT left on. There are barely 500 hours. Can I try to jump it with my diesel truck? Should lights on dash appear when hooked on with jumper cables? I don't get it? I've searched this forum..... Any help is appreciated.

 

[newbury]

Can you get a battery charger hooked up?

Try wacking the starter with a 3 lb sledge.

I've had starters hit a "flat" spot.

When hooked via jumper cable it should appear as normal.

 

[countrybumpkin]

Sounds like a dead battery or possibly dirty connections at the battery. If posts on battery are clean, then I would try jump starting it.

 

[hosspuller]

Unless you like spending money on starters, don't wack it with a 3# hammer....

It likely a 12 volt system, jump it with another 12 volt system. Or charge the battery

The best test is with a ammeter. That will tell if the starter is drawing too much current or the battery/cables can't deliver enough current.

 

[ritschner]

Judging from your join date, I would say your tractor and battery are approaching six years old. It may be time for a new battery.

 

[k0ua]

Get a simple voltmeter. Analog is best for this, as during a dynamic situation like starting, you can get a feel for how much the voltage drops to when the attempt to engage the starter occurs. Get another person to sit in the seat and operate the key. You put voltmter Directly on battery posts, NOT the battery clamps... Directly on the posts. What does it read? 12.6 volts? Hopefully within a range of 12.0 to 12.6..If it is reads below 12 volts, the battery could stand charging.

Have assistant turn on the headlamps. You stay on leads on the battery posts NOT the battery clamps. What does it read now... If it drops significantly while you are on the battery posts.. this indicates a discharged battery. Have assistant attempt to start tractor while you stay on the battery posts with the leads. What happens now? Chattering sounds.. What does the battery voltage drop to on the posts? Sigfificant drop? 10.5 volts or below? Discharged battery. Does the voltage stay up near 12 volts during all of these tests? Probably not the battery.

NOW move the leads over to the battery clamps. Does the voltage stay near 12 volts when the above tests with headlamps and starter attempt is made? If not then you have a high resistance between posts an clamp. Take em off an clean em up. Still have problem? Still wont't start. Possible high resistance in battery cable or cables.. That is a common problem. Also negative cable to frame of tractor high resistance is a common problem.. You can take voltmeter between a good clean frame point and the negative terminal of the battery.. It should measure 0 volts in all cases... Do you read voltage between negative post and frame? You have a connection problem forming a high resistance.

All of this takes far far longer to type out and read than it does to make these tests.. You should have an answer in a few seconds with a simple voltmeter and some knowledge.

If you were to ask me what are the chances.

1: Battery discharged, or defective, usually from buildup of sponge lead in bottom of the cells. This is the most likely things.
2: High resistance corroded battery clamp. Corroded cable internally, or bad connection to frame in that order. maybe one chance in 3
3: Defective starter relay, and or starter solenoid.. This is not very likely, about 1 in 10 or less but it is possible.
4: Starter? Not a chance in "heck"... Don't go hitting it with no dang hammer. You don't have a draggy starter.. one chance in 1000. Jeez.. a 3 pound hammer no less...

 

[Grateful11]

The battery in our L3940 lasted 5 years and it's used 365 days a year for about 30 minutes a day feeding cattle on a feedlot. It now has about 1200hrs on it. I suspect your problem is the battery. I can't remember if it's a Group 28 or 32. If it is the battery be sure to tell them it's for a diesel. We bought ours at a local auto and truck parts supply and the guy almost sold use a car battery and he told me he heard us mention it was for a diesel and sold us one with about an extra 100 CCA for about $10 more.

OT: Last year was the year of the battery for us. The 5140 had to have a new battery, the Kubota and the IH 686 had to have new set of batteries. This year it's been the year of the bearing, Combine blew a threshing rotor bearing and the manure spreader blew a main beater bearing.

 

[crazyal]

Clean all of the terminals, both the two battery terminals and where the positive wire attaches to the starter. Do the starter end with one of the battery terminals disconnected. Then a simple test is to turn the headlights on. If they dim then it's most likely the battery, if they don't then it's the starter.

 

[newbury]

<snip>
4: Starter? Not a chance in "heck"... Don't go hitting it with no dang hammer. You don't have a draggy starter.. one chance in 1000. Jeez.. a 3 pound hammer no less...

<snip> if they don't then it's the starter.

Seems like one of you are wrong about the possibility of it being the starter.

My comment on hitting it with a hammer is based on several vehicles I've had that developed a bad spot on the starter. I use a 3 lb hammer because that's what I carry for other things. Just this spring that was the method of starting my truck for several times before I could get it fixed. It got me going.

 

[rbargeron]

Got in my tractor moments ago, and it cranked once then nada. Turned the key, and a rattatatat sound emitted, now no sound at all..........

Reading posts closely is important. If it isn't even making a click, it's likely not a flat spot on the starter motor. The starter has two wires going to it - the big wire from the battery and the small wire to the solenoid. A quick test (brakes set, tractor out of gear) is to pull the small wire plug off and use a screwdriver to carefully bridge from the big terminal to the small one - if it cranks the battery and starter are ok and it's something else. If it is still lifeless check the battery & cable clamps.