I have a 340 with a 6 volt system that starts and runs fine when the engine is cold, but once I have started it and ran it to the point that it heats up to normal running temp the engine is hard to start if I kill it and try to restart. The coil is warm to the touch, but is not so hot that I can't touch it. The battery test out fine and is new, less than a month old. What would make the tractor so hard to start after it is hot? If I let the tractor set for a while and cool down it will start right up with out any problems.
- Thread starter jdbrad1
- Start date
Janicholson
Well-known Member
Three things I would check first.
The starter motor might be beginning to drag internally (worn bushings) and when it is hot, it has more drag than when cold (thousandths of an inch make a drastic change)
The cables might be small, When cold, copper conducts substantially better than when hot. 0gauge cables are really important. Car type #4 cables loose power at 6v under load.
Using a cheap (less than 15$) starter draw amp meter (auto store tool that is held against the battery cable, no connection required) should show about 300 amps. If more like 400 to 450, the starter needs to be looked at.
Sometimes advanced timing can also cause slight pushback at TDC. slowing cranking when warm and the fuel is easily fired up. JimN
The starter motor might be beginning to drag internally (worn bushings) and when it is hot, it has more drag than when cold (thousandths of an inch make a drastic change)
The cables might be small, When cold, copper conducts substantially better than when hot. 0gauge cables are really important. Car type #4 cables loose power at 6v under load.
Using a cheap (less than 15$) starter draw amp meter (auto store tool that is held against the battery cable, no connection required) should show about 300 amps. If more like 400 to 450, the starter needs to be looked at.
Sometimes advanced timing can also cause slight pushback at TDC. slowing cranking when warm and the fuel is easily fired up. JimN
Bob M
Well-known Member
Does it crank too slow to start when hot? If so JimN covers the fixes in his post.
However if the engine spins OK but isn't firing most likely it's a failing coil - ie. coil voltage output falls off when it's warm.
Try testing for spark with the engine warm. When cranking you should be able to jump about 1/2" with a hot, blue spark. However if you get a lazy yellow spark - or no spark at all -it's time for a new coil. I'd also replace the condenser at the same time - for a couple bucks more it's cheap insurance!
However if the engine spins OK but isn't firing most likely it's a failing coil - ie. coil voltage output falls off when it's warm.
Try testing for spark with the engine warm. When cranking you should be able to jump about 1/2" with a hot, blue spark. However if you get a lazy yellow spark - or no spark at all -it's time for a new coil. I'd also replace the condenser at the same time - for a couple bucks more it's cheap insurance!
Hello jdbrad1,
I have a Farmall A (1941) that I recently got.
It runs fine under no load.
I have been trying to plow up a field with a single bottom moldboard plow these last few days and I have been running into same problem as you described above. After the engine gets hot under load, the tractor won't start up again. Once it cools down, it starts right up. Have you resolved your problem by changing the coil/condenser?
I would like to know how you resolved it.
Thanks.
Yong
I have a Farmall A (1941) that I recently got.
It runs fine under no load.
I have been trying to plow up a field with a single bottom moldboard plow these last few days and I have been running into same problem as you described above. After the engine gets hot under load, the tractor won't start up again. Once it cools down, it starts right up. Have you resolved your problem by changing the coil/condenser?
I would like to know how you resolved it.
Thanks.
Yong
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