Questions about Replacing Positive Battery Cable MF 1250

[Old Gray Mare]

It's been a while since this old gal has needed your advice.

I'm replacing the positive cable on the MF 1250. Tired of surprise starting/no-start issues. Battery is only a couple of years old and is intermittently on a maintainer. The cable is corroded at both ends. Tractor has 520 hrs and runs very well.

I need 3ft with top post ends and an eye bolt at the starter. The present cable looks like 4awg (it's covered with the plastic tubing stuff). I'm looking online and wonder if 2awg would be better? Also, I found a cable with the battery end size of 19mm. Is this too big for a standard battery post? If the eye end is too big for the starter post, can I make it fit?

Going to an auto parts store is not an option...closest one is over an hour drive and my 93 diesel truck loves to suck money out of my wallet

Thanks in advance

 

[RjCorazza]

@Old Gray Mare
I don't have that model tractor, but the battery post connection is somewhat forgiving in terms of size. If too small you can shave off some lead so that the bolt squeezes the terminal to a smaller diameter. I measured a "regular" battery post in my garage, and it was 0.75" or about 19mm.
For the ringed end, there is wiggle room also. I have clipped a small section of rings in the past and made the ring smaller to fit better.
All that said, all of the larger batteries that I've dealt with had very similar (if not practically identical) terminal diameters with the exception of my wife's Prius starting battery.
There is no penalty in going to 2ga cable, but not necessary imho.

 

[fuchifarm]

The factory cable is 30mm copper which is like 2.4awg. 2awg is a good replacement cable.
However:
You don't need to replace the cable if the insulation is intact. There should be enough length to cut the battery terminal end off, trim an inch of insulation off, and install a new clamp on terminal. I suggest buying a set of brass terminals like in the below picture. For the ring terminal end grab some fine grit sand paper and go to town on the terminal and the copper bolt on the starter. They will clean up quickly. If the copper of the cable is oxidized you can use vinegar and baking soda to clean the wire before clamping it down. Now I do recommend upgrading the ground wire from batter to chassis. The oem one is too low gauge.

The other thing to look out for is the black with white wire that goes from the wide connector on the right side near the fuse block to the spade connector for the starter solenoid. The starter switch can get dirty and produce a voltage drop on this wire. I added a 12vdc relay and added a ring terminal from the starter to the relay switch terminal. Other switch terminal to the solenoid spade. Then I moved the black with white wire to the driver terminal and ground wire to the opposite terminal. This provides a nice clean 12vdc to the starter solenoid and the switch still provides the same safety features. The relay will still switch even if the voltage drops down to 9vdc. This is much cheaper than replacing the switch. I have the wiring diagram and service manual for the 1240. Most all of it is the same for the 1250.

If you open the wiring diagram I attached. The main culprits of starting issues with these tractors is starting at terminal 50 of the key switch and going to the starter solenoid spade terminal. You can follow the Black with blue stripe wire from the switch terminal to the safety relay that is behind the dash. If you remove the dash be sure not to lay the meters upside down or flat. It is best to keep them upright. To remove the dash I remove the screws for the console shroud and the screws for the dash. Tip the steering wheel down as far as it will go and then slide the whole assembly forward. You can install the automotive 12vdc relay either at the starter or behind the dash. For simplicity I did mine at the starter. I utilized the long bolts on the starter to mount the relay and then made some short jumper wires using 12awg stranded copper and crimp on spade and ring terminals. If the starter hangs sometimes (turn switch and nothing happens) you may want to get the starter solenoid parts replaced. The amazon link has a kit with all the parts to rebuild the solenoid. It only takes 2 bolts to remove the starter and then there are 4 screws holding the back plate on the solenoid to access the electrical components. There is another kit that has the bolts and and washers and other bits. I didn't need those parts to do the rebuild. The plunger and the curved contact were the 2 important pieces for my starter.

https://www.amazon.com/gp/product/B0031HMS7C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[Old Gray Mare]

The factory cable is 30mm copper which is like 2.4awg. 2awg is a good replacement cable.
However:
You don't need to replace the cable if the insulation is intact. There should be enough length to cut the battery terminal end off, trim an inch of insulation off, and install a new clamp on terminal. I suggest buying a set of brass terminals like in the below picture. For the ring terminal end grab some fine grit sand paper and go to town on the terminal and the copper bolt on the starter. They will clean up quickly. If the copper of the cable is oxidized you can use vinegar and baking soda to clean the wire before clamping it down. Now I do recommend upgrading the ground wire from batter to chassis. The oem one is too low gauge.

The other thing to look out for is the black with white wire that goes from the wide connector on the right side near the fuse block to the spade connector for the starter solenoid. The starter switch can get dirty and produce a voltage drop on this wire. I added a 12vdc relay and added a ring terminal from the starter to the relay switch terminal. Other switch terminal to the solenoid spade. Then I moved the black with white wire to the driver terminal and ground wire to the opposite terminal. This provides a nice clean 12vdc to the starter solenoid and the switch still provides the same safety features. The relay will still switch even if the voltage drops down to 9vdc. This is much cheaper than replacing the switch. I have the wiring diagram and service manual for the 1240. Most all of it is the same for the 1250.

If you open the wiring diagram I attached. The main culprits of starting issues with these tractors is starting at terminal 50 of the key switch and going to the starter solenoid spade terminal. You can follow the Black with blue stripe wire from the switch terminal to the safety relay that is behind the dash. If you remove the dash be sure not to lay the meters upside down or flat. It is best to keep them upright. To remove the dash I remove the screws for the console shroud and the screws for the dash. Tip the steering wheel down as far as it will go and then slide the whole assembly forward. You can install the automotive 12vdc relay either at the starter or behind the dash. For simplicity I did mine at the starter. I utilized the long bolts on the starter to mount the relay and then made some short jumper wires using 12awg stranded copper and crimp on spade and ring terminals. If the starter hangs sometimes (turn switch and nothing happens) you may want to get the starter solenoid parts replaced. The amazon link has a kit with all the parts to rebuild the solenoid. It only takes 2 bolts to remove the starter and then there are 4 screws holding the back plate on the solenoid to access the electrical components. There is another kit that has the bolts and and washers and other bits. I didn't need those parts to do the rebuild. The plunger and the curved contact were the 2 important pieces for my starter.

https://www.amazon.com/gp/product/B0031HMS7C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

View attachment 783779

Thanks for all the info! It's way beyond my mechanical skills, sadly.

When I replaced the battery, I also cut the battery terminal end off until there was good copper and replaced the end. Cleaned with baking soda, put on a felt washer thing, and coated it with (after hooking it up) preventive goop. Corrosion still happened, so my thinking is the cable is causing the problem? I can see corrosion on the starter end, too. Replacing cable will be easy-peasy.

The negative is a braided thing. Should I replace it, too? It doesn't corrode.

Many years ago, the kind folks on here showed me how to exclude the safety relay for the starter, since the tractor would not start. Cured that problem and it always starts (when the battery is ok).

This current no-restart happened in a stall entry at the barn! I was cleaning out the manure, had already made a couple of trips, filled the loader and all it would do was click the glow plugs! It was the worst place to get stuck! I checked fuses, fuel, cable connections, ignition, etc. Battery only read 12.25 on voltmeter. Saw corrosion on positive post so got the old charger out. Jumped it and instantly tractor started. Yay! Dumped the load and parked it. Now there is no glow plug noise.

I'm getting way too old for this much excitement lol.

 

[Old Gray Mare]

@Old Gray Mare
I don't have that model tractor, but the battery post connection is somewhat forgiving in terms of size. If too small you can shave off some lead so that the bolt squeezes the terminal to a smaller diameter. I measured a "regular" battery post in my garage, and it was 0.75" or about 19mm.
For the ringed end, there is wiggle room also. I have clipped a small section of rings in the past and made the ring smaller to fit better.
All that said, all of the larger batteries that I've dealt with had very similar (if not practically identical) terminal diameters with the exception of my wife's Prius starting battery.
There is no penalty in going to 2ga cable, but not necessary imho.

Howdy.

Thanks for the size info. I've found a 2ga cable with 19mm battery end and 3/8" ring end. Made in the USA!

Do you use corrosion prevention? Which one?

 

[RjCorazza]

Howdy.

Thanks for the size info. I've found a 2ga cable with 19mm battery end and 3/8" ring end. Made in the USA!

Do you use corrosion prevention? Which one?

I use either PermaTex spray, or a heavy duty metal protector (not made for battery terminals). The metal protector leaves a thin film on the terminals that seems to work just as well as the PermaTex product. I have used it on my golf cart for years, and there has never been ANY corrosion.
Make sure to apply after the terminals are fully tightened down!

 

[fuchifarm]

A ground that is slightly loose can cause these problems as well. I would at minimum check the battery lug and ensure it is tightened down good.

My 1240 had a cheap 6awg cable from likely walmart or autozone etc on it. The cheap split metal ring lug had rusted through on one side and made it loose. It had obviously been replaced at some point. It would start fine I would do something go to start it again and it would be dead. Finally pulled on the ground wire while key was on and it started ticking again.

A good 2awg 2ft cable with lug and a 3/8" ring terminal I believe is what I used to replace it. There are several bolt locations on the right side to choose from for the ground wire to go to.

Since you already bypassed the safety relay and you aren't having issues with starter for now just keep the extra info as backup for the day your starter clicks and doesn't start spinning. If you ever get into a situation where you think its the key switch causing problems (black with white stripe wire voltage is under 11.5V while battery voltage over 12V) you can utilize the old safety relay to get a good 12v to the starter solenoid. To use the safety relay you can pull the black with yellow stripe wire spade out of the connector and move the black/blue wire spade to its spot. Then where the black/blue was make a jumper wire to connect to terminal 30 on the key switch. Amazon /auto parts stores also have some spade to double slot connectors so you can add the wire at the connector that goes to terminal 30.

I have had lots of electrical gremlins with mine. Lots of sandy dust here when its dry and it finds its way into the spade terminals all the connections are made with. The fuse block is the worst right now. I think I will end up having to replace a few terminals. Right now if I hit a bump my fuel/temp gauge lose power and then comes back on the next bump. I can wiggle the fuse and it will come and go.

Anyway I have email alerts turned on here so if you ever need help figuring out something with it feel free to message me.

 

[DJ54]

I get my battery cables here: Battery Cables - Custom Made Battery Cables Very nice marine grade with choice of sheath color, and whatever ends are needed, plus shrink wrapped at terminals. Ships by priority mail, and I usually have them in 3 days.

 

[WranglerX]

Don't screw around with funky repairs, get proper new cable from online or FLAPS sources.... Funky repairs will only come back to haunt you at some time when its most inconvenient for you...

THis is the best stuff ever.... Never had/have a corrosion issue when using this.... One tube will last a lifetime... Only caviat is you have to have clean battery/cable terminals to start with...