Irritated cuz tractor won't start

[robbyr]

The Mahindra 4500 is parked right in the way in my back yard but won't start. Was using it last Saturday and everything was fine. Sunday it wouldn't start. Starting some time I ago it started having issues with a safety switch I think. I could slide pto lever back and forth slowly while holding key on til the starter engaged. Then I found sometimes I could wiggle the range selector lever in neutral position and that seemed to work. Sometimes neither would work and I'd jump across the solenoid and it would start right up. Next time I might turn the key and it start right up. Sunday nothing worked. Battery is only 9 months old but I cleaned cables and put charger on anyway. Turn key or try the screwdriver thing and it clicks once and that's it. Nothing else. Battery tester shows in "green". Thought maybe just didn't have enough voltage to engage starter but kinda scratching my head now.

 

[k0ua]

The Mahindra 4500 is parked right in the way in my back yard but won't start. Was using it last Saturday and everything was fine. Sunday it wouldn't start. Starting some time I ago it started having issues with a safety switch I think. I could slide pto lever back and forth slowly while holding key on til the starter engaged. Then I found sometimes I could wiggle the range selector lever in neutral position and that seemed to work. Sometimes neither would work and I'd jump across the solenoid and it would start right up. Next time I might turn the key and it start right up. Sunday nothing worked. Battery is only 9 months old but I cleaned cables and put charger on anyway. Turn key or try the screwdriver thing and it clicks once and that's it. Nothing else. Battery tester shows in "green". Thought maybe just didn't have enough voltage to engage starter but kinda scratching my head now.

Robby, you have read the dozens of thread responses I have written about "no start" in the various forums thru the years right? You do own a voltmeter correct? You know what you must do.

 

[robbyr]

Robby, you have read the dozens of thread responses I have written about "no start" in the various forums thru the years right? You do own a voltmeter correct? You know what you must do.

No sir I have not seen those threads but will look. No I don't have a voltmeter mainly because I never knew how to interpret one or how to properly use one. After my FIL passed I found his multimeter but it quit.

 

[k0ua]

No sir I have not seen those threads but will look. No I don't have a voltmeter mainly because I never knew how to interpret one or how to properly use one. After my FIL passed I found his multimeter but it quit.

Well, then you are probably going to need some help. Do you have anyone that could help you?

 

[robbyr]

Well, then you are probably going to need some help. Do you have anyone that could help you?

Maybe. Can you post a link to the thread you were referring to?

 

[jeff9366]

k0ua is one of the most helpful and reliable responders here.

It could be the battery but more likely it has to do with your PTO interlock "safety" switch, the transmission interlock "safety" switch or the under seat interlock "safety" switch or some combination. These interlocks can be difficult to adjust properly on a tractor with only a few hours, even for a tractor mechanic. However, once adjusted properly and with a few engine hours the settings usually hold thereafter. That is my experience with two new Kubota tractors.

Here is a LINK to the universe of 210 threads started by k0ua:
http://www.tractorbynet.com/forums/search.php?searchid=1821323

 

[robbyr]

k0ua is one of the most helpful responders here.

It could be the battery but more likely it has to do with your PTO interlock "safety" switch, the transmission interlock "safety" switch or the under seat interlock "safety" switch or some combination. These interlocks can be difficult to adjust properly on a tractor with only a few hours, even for a Mahindra mechanic. However, once adjusted properly and with a few engine hours the settings usually hold thereafter. That is my experience with two new Kubota tractors.

Here is a LINK to the universe of 210 threads started by k0ua:
http://www.tractorbynet.com/forums/search.php?searchid=1821323

But even when there is safety switch issues shouldn't the starter engage as soon as voltage is applied? What if I use one of those remote battery jumpers and clip positive side on starter then touch negative to frame? Shouldn't it engage?

 

[RNeumann]

From your description you have had known issues for several months. I'd start with known bad or out of adjustment parts. It's hard to ignore a known issue that prevents the tractor from starting when you are having an issue getting it started.

 

[k0ua]

But even when there is safety switch issues shouldn't the starter engage as soon as voltage is applied? What if I use one of those remote battery jumpers and clip positive side on starter then touch negative to frame? Shouldn't it engage?

If there is good voltage AND the ability to pass a large amount of current (around 200 amps) on the starter/battery connection, and then you jump to the bendix (otherwise known as the starter solenoid) then the starter should spin as long as the ground connection to the frame and the path back to the battery negative is low resistance. Now I have said a mouthful there with a lot of "ifs and buts". Of course you run a risk of running over yourself if the starter engages and the tractor is in gear. You know you have safety switch issues, and probably still do, but if you have tried to "roll over the starter" and it wont engage by your bypassing methods then the safety switches are not your immediate problem. The most likely thing is a defective battery cable or connection . And you cant tell by looking at them if they are defective. You must measure for a voltage drop, indicating a high resistance. I always start at the battery posts, and work outward from there. Keep in mind you are not just looking for 12.6 volts, you are looking for good voltage under load. This indicates the ability to pass current. A large wire is a very low resistance conductor. Or it is supposed to be. But they often aren't after the acid fumes get to them for a while.

The in series safety switches are usually in line to the coil of the starter relay. This relay is usually energized by the start position on the key switch, or a computer module in many cases. The starter relay sends voltage and a fair amount of current towards the starter solenoid (bendix) which makes both a very large current electrical connection to spin the starter motor, and also makes a mechanical connection to bring the bendix gear into engagement with the flywheel teeth on the engine.

Remember voltage (volts) alone wont spin a starter, you must deliver current (amps) while maintaining a good voltage to deliver POWER to the starter. Volts X Amps equals Watts of power. Power spins starters. Sure the voltage always drops some from a battery, the battery posts connections, the battery cables and the starter connection. All drop a little, but your starter will spin fine on 10.5 volts while pulling close to 200 amps. That is over 2 kilowatts of power being consumed by the starter. Probably more on a cold day.

 

[k0ua]

But even when there is safety switch issues shouldn't the starter engage as soon as voltage is applied? What if I use one of those remote battery jumpers and clip positive side on starter then touch negative to frame? Shouldn't it engage?

It depends. If you clip the portable battery to the large starter Lug that is already hooked to the tractors battery and ground, nothing will happen, you have just effectively put a parallel battery across the main tractor battery. The tractor SHOULD NOT crank.

If you clip it across the starter solenoid lug and the frame ground, the starter solenoid (bendix) should pull in (engage) and IF the connections are all good and the main tractor battery is good, the starter will spin.

Most people do this with a screwdriver by putting it between the main battery lug and the starter solenoid lug. Some have run over their silly selves about 1/2 second later as the tractor lurches forward and one of the rear tires smashes them to the ground.