Runs but then nothing- ideas??

[DrLandraceFarmer]

Hi all- glad to have a forum to bounce around ideas. My 49 cub was purchased with no battery. It does have a 6 volt system (checked the regulator) and the generator puts out 7-8 volts. I bought a new 6 volt battery and hooked up as positive ground. The amp meter indicated charging when running, discharge with switch on/not running.

It had some fuel tank issues (rust and gunk), but I’ve cleaned and coated it. It’s has been running better than a new car since. However, a couple of weeks ago it began having a few symptoms. It would begin to sputter and die, then wouldn’t start back. The coil was hot as fire. Let it cool, it will start back up and drive back to the house. It seemed like a classic failing coil (and no idea how old the coil was). I order a new 6 volt coil and replaced it today. Tractor fired right up and I drove around say 45 minutes. Stopped, went to see if I could start back up-nothing?? The coil was say warm to the touch, but could easily hold my hand on it.

So, while the 6 volt system is relatively straight forward, I’m a little stumped by this. Seems unlikely that the new coil is also bad. I’ve not replaced the points/condenser. It has new plugs/wires.


Poor ground connections? Bad condenser? I’ve been through the 6 volt wiring diagram and nothing jumped out at me as wrong. Am I missing something? Any advice or ideas appreciated.

[Glen]

Hi,
A 1949 Cub originally came with a magneto. The coil is under a cover on top of the magneto. It is a special magneto coil.
It sounds like you have a car type coil on your Cub.
Some magneto coils quit, and people wire in a car type coil.
But a Battery Ignition unit, which came out in 1950 on Cubs, uses a car type coil also.
Some Cubs have been changed to a Battery Ignition unit.
You didn't say if you have a magneto, or a Battery Ignition unit.
The magneto is shown beginning on page 30 of the manual below.
Check the Cub's serial number, on the plate by where the long steering shaft goes into the steering gear. It shows on page 2 in the manual below where the tractor serial number is.
You can look up the year of the Cub using the serial number at the top of the page at Cub Info.

A 1949 Cub came with a cutout, or Relay IH called it, on top of the generator, and the 4 position charge rate and light switch on the dash. The Relay is not a voltage regulator, you had to choose the charging rate yourself, using the switch, the switch has L, Low, or H, High charge.
It shows how to use the switch on page 34 of the manual below.
If the Cub has equipment newer than 1949, it may be newer, that's why I suggested checking the serial number.

A new coil can be defective. Try doing a spark test.
Remove the center spark plug wire from the distributor cap, put the Cub in neutral, turn the ignition switch to on, hold the wire by the insulation with the end about 1/4" away from a bare place on the engine. The spark should jump the gap, and be blue or white. Yellow is weak, and the engine may not run.
The ignition points and condenser may need service, points get old and burned, that can cause hard starting, eventually power doesn't go through them.
TM Tractor has new points and condenser.
The manual below shows how to replace and gap the points for the magneto. The points need the right gap. The Battery Ignition unit is in newer Cub operator's manuals.

You have been a member here for a while, but I don't know if you have the Cub owner's manual.

The Cub owner's manual can help you learn about maintenance that the Cub needs.

Below is the 1949 Cub owner's manual. The experts on here recommend people read it. It has lots of info about operation, maintenance, and lubrication. There is a table of contents on page 1.
It shows how Cubs originally looked in it. The lube section begins on page 14.

http://farmallcub.com/rudi_cub/www.clea ... index.html

It shows the electrical system that a 1949 Cub originally had.
Page 33 has a pic with the hood off, showing the electrical system.
Cubs made before mid 1964 originally had 6 volt, positive ground electrical systems.

The 10 weight motor oil mentioned in the manual for the Touch Control was changed later to Case IH Hy-Tran fluid. It is sold at Case IH dealers.
There are other brands, be sure it works with IH hydraulic systems before buying one.

I would check or change all the oils before using the Cub. Using it with low oil in a gear housing can damage the parts in the housing.
There are 3 separate gear housings, with 3 separate oil levels to check, in the rear area of a Cub, the transmission, and 2 final drives.

The transmissions in Cubs commonly get water in them, from rain, or condensation inside the housing over time.

The air cleaner is an oil bath air cleaner. Dirt that is sucked in settles to the bottom of the oil cup. It should have clean, light motor oil in the oil cup to work right.

There is a search box at the top of the page, to the right of the Farmall Cub, you can find info in posts that have been made.

Below is a pic of a Battery Ignition unit, and part of the voltage regulator, used beginning in 1950.
The regulators were in the position shown, on a mounting bracket.

[DrLandraceFarmer]

Hi, thanks for the feedback. I checked the serial numbers and casting info when I got the tractor. It is a 49, but was obviously switched over to a battery ignition at some point. Definitely not a magneto any more, but left as a 6 volt system. I’m familiar with a simple spark test and plan to check it. Today just got very busy and I thought I’d just put it out there and see if something stuck.

I’m decent in the mechanical sense and grew up working on old farm trucks and tractors. The 6 volt system is new to me-and while its seems straight forward there are always things we easily overlook.

As far as routine maintenance, all good-all covered. When this issue started my experience said the coil is failing. It is true that the new coil could also be “bad,” but I’m leaning toward replacing points/condenser no matter what. That’s about the only thing I’ve not replaced in the tune up and refresh category.

Yep- I have all the manuals and wiring diagrams. I did a search of the forum before posting and didn’t find a similar thread.

I had questioned the polarization early on when I was verifying that it was indeed a 6 volt system. However, the amp meter reads correctly when hooked up as 6 volt positive ground. I gather though, that would only result in no charging of the battery and effect how the tractor runs.

To all that are active and have worked to build this community, thank you- what an amazing resource! I was certainly glad to find it after I acquired my Cub.

[Gary Dotson]

I would replace the points and condenser and give it another try. The old coil running as hot as it was, probably arced the heck out of the points, they are most likely, pretty much, burned up.

[Waif]

Finish your tune up...

6 Volt wants the best electrical flow you can give it.
I had fun with random won't starts with my first Cub due to a bad battery ground. A case in which how it looked didn't matter compared to how it functioned. That tractor really likes it's now braided ground cable.

[DrLandraceFarmer]

Points and condenser being ordered today. I’ll run over the ground contacts to be sure everything is clean. Thanks for suggestions and feedback.

[Eugene]

During your engine tune up, make sure the clamp on the coil is tight to the coil and engine. Some coils use the coil's case as the coil's secondary winding ground.

[Glen]

Below is info about replacing the points and condenser in a Battery Ignition unit, if you need it.
The 1st page shows how to get to them.
It is probably easier to see the pics on a computer with a screen bigger than a phone.

http://farmallcub.com/rudi_cub/www.clea ... age-11.jpg

http://farmallcub.com/rudi_cub/www.clea ... age-12.jpg

To replace the points, I sit down next to the engine, on a lawn chair, or if the Cub has a rotary mower on it, let the mower down to the floor, and put something on it to sit on.
Put a towel on the floor to catch any screws you might drop.

You need a good light, a short screwdriver with a sort of wide blade, and a 11/32" open end wrench for the nut that holds the end of the point spring.
Tighten the nut gently, there is an insulation there in the side of the unit, it can break if you tighten the nut hard.
Be sure to set the point gap right, like the manual shows.

TM Tractor has new points and condensers, below is their listing, you can look at the pics.

http://www.tmtractor.com/new/el/367fp.htm

They also have the insulation for the post, below is the listing.

http://www.tmtractor.com/new/el/957fp.htm

The cap and rotor might need replacing if the contacts look burned. Sometimes the contacts can be scraped and sanded to improve them.

The ignition timing has to be set right to have good power. If it is off some, the power can be less than it should be.
IH says in the Cub service manual for Cubs with a Battery Ignition unit, to check it with a timing light, like are used on cars in the past.

[DrLandraceFarmer]

Update:

So, I did replace the points, condenser, rotor button. The tractor did perk up just a bit after that, but it was already running very well. The problem of no start after running, along with a hot coil persisted.

I took the hood off again and went over all the wiring. Finally, noticed a couple a creative wiring endeavors of a previous owner. Obviously, corrected the wiring. The previous owner re-routed some wires and jumped a couple together. I hadn’t noticed it before, but wasn’t really looking.

So I think, this must have been the cause of my woes!! Put everything back together, started up and ran well, but the problem persisted.it just wouldn’t start back up unless it sat for 39 minutes and cooled down. Finally, got another replacement coil for the new coil I had already installed. Problem solved! The old coil had gone bad, the new replacement coil was bad, but the new new coil works!

Perhaps the previous creative wiring caused the old coil to fail prematurely. But the first new replacement was bad out of the box.

Can’t trust that new parts are always good - not anymore.

[Glen]

Hi,
Good that you got the Cub to work better.

The ignition timing needs checking too, so the engine runs good.