Hello. I have a 1951 H that will run for ten minutes or so and then loses spark which leades to a stall or loss of power. I have changed the points, rotor, plugs, condensor and coil. This tractor has been converted to a 12 volt system. From the seat you can see into the back of the generator. There is sparking by the left side brush. At idle, I noticed the the brush stoped sparking as the motor tried to stall. Then I could see sparking in the back of the generator and the motor would pick back up. Could the generator be killing the spark? It has an external voltage regulator. Could this cause the problem? I have changed everything else. Thanks. -Dave Jones
- Thread starter djone110
- Start date
ScottyHOMeY
Well-known Member
Alternator or generator on 12v? You normally don't see into a generator on 12v. Not out of the question but wicked unusual.
And most alternators are internally regulated and don't require an external regulator. Again, nit unheard of, but rare.
And who knows what else may be out of whack?
Is this a new problem on a tractor that has been running well otherwise?
Sounds a little discombobulated to me.
And most alternators are internally regulated and don't require an external regulator. Again, nit unheard of, but rare.
And who knows what else may be out of whack?
Is this a new problem on a tractor that has been running well otherwise?
Sounds a little discombobulated to me.
Bob M
Well-known Member
Has a ballast resistor been added in series with the coil primary? Or has the original 6 volt coil been swapped out for a 12 volt coil?
If not, good chance the coil overheats after running a few minutes and loses its spark. (It's also rapidly wearing out the breaker points...)
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Light sparking at the generator brushes is normal when it's charging. Heavier sparking however is a sign the brush are wearing out. Note the sparking will disappearing at idle is normal since the generator does not charge at idle).
This generator sparking should not affect the ignition spark whatsoever.
If not, good chance the coil overheats after running a few minutes and loses its spark. (It's also rapidly wearing out the breaker points...)
---
Light sparking at the generator brushes is normal when it's charging. Heavier sparking however is a sign the brush are wearing out. Note the sparking will disappearing at idle is normal since the generator does not charge at idle).
This generator sparking should not affect the ignition spark whatsoever.
Thanks for the response. Yes an external resister has been added. I checked the power going in and out of it. The test light was dimmer going to the coil. It seamed ok but I changed anyway out of desperation and they are not expensive. Thanks again. -Dave Jones
Also,I noticed that the tractor will stay running at idle and the problem really happens under load (mowing). I did not reset the timing as I have not figured out how to set it.
Also,I noticed that the tractor will stay running at idle and the problem really happens under load (mowing). I did not reset the timing as I have not figured out how to set it.
Brownie 450
Member
Scotty---if he has a generator from a 560, the brush/ commutator area is visible--at least our 560 had an open rear.
When the tractor dies, take a jumper wire with alligator clips & connect it between the battery hot terminal & the hot side of the resistor going to the coil. See if the tractor will start & run. This will eliminate all wiring from the battery through the ignition switch & up to the coil resistor. You likely have a connection or wire--even the ignition switch itself that is conducting when cold--& develops a high resistance when the engine is operating.
Don't overlook the new condenser being bad also.
When the tractor dies, take a jumper wire with alligator clips & connect it between the battery hot terminal & the hot side of the resistor going to the coil. See if the tractor will start & run. This will eliminate all wiring from the battery through the ignition switch & up to the coil resistor. You likely have a connection or wire--even the ignition switch itself that is conducting when cold--& develops a high resistance when the engine is operating.
Don't overlook the new condenser being bad also.
That was my first thought. It sure felt like a bad coil. I put a new one one and it made no difference. This tractor worked perfectly for the last 3 years and this problem just started. I've changed every part I can think of to change. I may have to put it all together and get professional help. Thanks again.
Janicholson
Well-known Member
Make sure it is actually a spark issue. Fuel delivery to carb will also act that way. There is the inlet in the tank, the screen in the sediment bowl, and a screen in the inlet to the carb, all need to be clean to run at high speed. JimN
Changed fuel filter, drained and re-filled gas tank with fresh gas, cleaned sediment bowl, added dry gas treatment and I jumped off while it was hot and dying and verified the spark was gone for a short time. Wait ten minutes and it will start and go again. Its a great thought and makes sense what you said. Thanks.
Changed fuel filter, drained and re-filled gas tank with fresh gas, cleaned sediment bowl, added dry gas treatment and I jumped off while it was hot and dying and verified the spark was gone for a short time. Wait ten minutes and it will start and go again. Its a great thought and makes sense what you said. Thanks.
I put a test light on the resister yesterday. It showed power as tractor was dying. I also checked power at the coil itself and it was good. I even jumped power straight to the coil thinking I already had two coils and I could get away with full battery power for a few minutes.
Getting back to this generator question. Earlier today I could see spark at only one set of brushes but it was still charging over 14 volts above idle. Now I see no spark at either brush and it is only charging 12.2 volts which is not enough as the battery itself is 12.6 volts. This may not be causing my other problem but it is an issue that has to be delt with. Would the best way be to get an all in one alternator/regulator assembly? Or should I try to get the generator fixed? Thanks. -Dave Jones
Getting back to this generator question. Earlier today I could see spark at only one set of brushes but it was still charging over 14 volts above idle. Now I see no spark at either brush and it is only charging 12.2 volts which is not enough as the battery itself is 12.6 volts. This may not be causing my other problem but it is an issue that has to be delt with. Would the best way be to get an all in one alternator/regulator assembly? Or should I try to get the generator fixed? Thanks. -Dave Jones
Doug - Iowa
Member
Lots of great advice below but I'll add my 2 cents. My H has the distributor that sits upright, not on its side like many do. I was having lots of problems that seemed to indicate bad spark but just couldn't figure it out. Tried all the usual stuff. Then I took the distributor out to check bushings etc and found the bevel gear worn out. Replaced that and problems solved. So if you've to that type distributor, be sure the bevel gear is good.
Janicholson
Well-known Member
Almost every one on this board believes that the clear plastic filters are too restrictive on a gravity feed system. NAPA makes a filter for gravity feed. it is not as small. The restriction of a plastic filter seems at first to be irrelevant, but a fuel pump equipped vehicle has 4 to 8psi applied, whereas the gravity feed has only a 15 inch head of pressure. The small plastic filters also have a tough time with flow when even a little plugged up. I would either toss it, or use a gravity flow unit. Bad coils can come from the factory. A true 12v (no external resistor required) coil used with a resistor will not give good spark, (it thinks it is getting 4 volts or so.)
also check the side play in the distributor shaft. If you can see or feel play it is too much. JimN
also check the side play in the distributor shaft. If you can see or feel play it is too much. JimN
"Almost every one on this board believes that the clear plastic filters are too restrictive on a gravity feed system."
I don't.
I do & have for years used gravity feed type inline plastic/paper filters on lawn mowers, air compressor, and motorcycle/ATV engines that have a lot less than 15 inch pressure head (near empty only about 3 inches) with NO problem what so ever. Just get the gravity vs pressure filter...simple.
I don't.
I do & have for years used gravity feed type inline plastic/paper filters on lawn mowers, air compressor, and motorcycle/ATV engines that have a lot less than 15 inch pressure head (near empty only about 3 inches) with NO problem what so ever. Just get the gravity vs pressure filter...simple.
You need to see what your charging voltage is at the battery when its running, check the battery voltage again when it quits. You may need to have that generator checked for voltage output.
If its not charging around 14 volts you won't have
enough voltage for your tractor's ignition. A low voltage problem when you have a mag doesn't need battery voltage. Hal
If its not charging around 14 volts you won't have
enough voltage for your tractor's ignition. A low voltage problem when you have a mag doesn't need battery voltage. Hal
To expand on what JMOR and Jim says about inline filters. I've used the plastic inline filters. The cheap G2's from wally world and parts stores and the napa inline filters for about 5 bucks. Flow when new isn't a problem. But they don't fix the problem which is usually rust and gunk in the fuel tank that keeps breaking loose. Then every few days of use they do plug off from the rust and the engine quits. After going through inline filters every few days at a few bucks a pop, then I try to derust the tank but I still can't ever get it all. So it is cheaper to go with a sediment bowl like the tractor had when new. And it saves the aggravation of being shut down out in the field and having to change the filter assuming there is a spare or two being carried with you. I've had to make the walk to get another one which isn't any fun. Put a screen or rubber hose on your sediment bowl intake.
Mowers and such with plastic tanks don't have the rust issues so they rarely plug off.
Mowers and such with plastic tanks don't have the rust issues so they rarely plug off.
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