Maybe we should have gotten a crankcase heater in the L3940!

[JoeL4330]

first, cheapest test: take your car/truck, and jumper cables to the tractor; jump and start ...if it spins right up, then it's your charging system (belt, as suggested, most likely) or your battery ...clean the battery posts and connectors as stated (and connection to starter).

Once you've checked the battery, the belt, cleaned the terminals, etc. ...
If it starts properly with jumpers, or just after being externally charged, then your alternator is not sized to your electrical load (work lights, etc) or your operating style: start-shutoff-start-shutoff-start-shutoff... So, let it idle rather than shut it off at every little stop (assuming it will charge at idle, which is easily tested)

But, all said and done, I still feel you'll come to love your battery-tender...keeps battery warm, so no need (at your temps) for a battery blanket...and, while a block heater is a good investment, it doesn't seem like the ticket for not starting at 40F. If you aren't always parked near electricity, look into a small solar charger.

At 40F, slow spinning means either you put 90wt gear oil in your crankcase or you need juice.

If you try the jumper cable route, let us know the results.

 

[KWentling]

I'm still betting that this is just a case of not enough run time to replenish what is drawn from the battery by the glow plugs and cranking. If there is some idling time in there it probably isn't charging at all then. Just keeping the tractor at mid throttle all the time might be enough to keep it charged. Probably going to have to run it for an extended time now to get caught back up or put a charger on it. Would be good to check the belt for tightness and to make sure the alternator is putting out 14+ volts as it should. I don't think battery blankets, synthetic oil, and all that is needed at 30˚ temps. If it was below zero, then it would be good. A battery tender might be useful, but I think more RPM and maybe running it a little longer will take care of it. This is all assuming the alternator, battery, cables etc. are good.

Kim

 

[Recoveryhill]

I have a good volt meter and I'm going to take some readings.

So what are your readings? This is surely the first place to start.

 

[Johnbro]

Very easy way to check the health of your battery:

Remove the terminals so there's no load on teh battery.
Charge it fully until it reads 12.6v with no charger or load on it.
Let it sit 24 hours.
Check the voltage again. if it drops to less than 12.3 v it's shot.

another thing to do is put your VM on it BEFORE you start it in the morning. A fully charged 12 v battery should read 12.68v. 12.2v is 50% charge.

finally, when your engine is running and the alternator is charging fully, you should initially see around 14v at the battery terminals until the charge is restored from spinning the starter to fire the engine.

 

[Grateful11]

Ok I finally got some numbers:

Battery before starting, cold: 12.6 V
Battery after running for about 25-30 minutes no stopping and not letting RPM's drop below 1300, engine off: 12.8 V
Voltage at battery with engine warmed up and running at 1500RPM's 14.2 V

 

[Willl]

Them good numbers. :thumbsup:

 

[crazyal]

I would say your battery voltage and charging system are OK. When you first started it (cold) did it turn over slowly?

I think a couple of tests I would try now is run it for a half hour (or more) to make sure your battery has a good charge. Shut it off and then let it sit overnight or a few days when you think the day you go to start it will be cooler. Turn it on, wait until the glow plug light goes out and start it, it should turn over just fine. My 4240 will turn over in mid 20 temps just fine.

If it's still turning over hard try and get someone to measure the voltage as you try to start it (I can always check mine to give you a reference voltage). If your still having problems I would think possible issues could be a bad battery (may not have the reserve it should), a bad connection, or a bad starter.

 

[kevinj]

I have an L3940 which is stored in an unheated building.

Starts fine down to zero. Don't get much colder than that in the building here in Michigan.

Started it yesterday at 30° and it starts like summertime.

It of course rattles and smokes a bit:thumbsup:

The glow plugs have a timer on them. Mash the clutch and crank as soon as the light goes out or the plugs cool off. Stay with the starter a couple second after it fires. Also hold the clutch down till the engine smooths out or it may stall.

 

[leonz]

Ok I finally got some numbers:

Battery before starting, cold: 12.6 V
Battery after running for about 25-30 minutes no stopping and not letting RPM's drop below 1300, engine off: 12.8 V
Voltage at battery with engine warmed up and running at 1500RPM's 14.2 V

You need a new high cranking amperage battery, You need to remove the old battery and charge it over night and have it load tested, Your alternator is pumping the amperage and voltage that the windings are generating so the readings are meaningless.
If you have answered this already my apologies; but have you checked the belt?


The starting and stopping should not affect it, but as the tractor is not wound up to charge the battery thats a lot of the problem.

 

[Gator6x4]

What weight oil do you currently have in the machine? You may have to switch to synthetic. A good first place to start looking when a tractor is slow turning over in cold weather is the oil/weight/when last changed.