What leaks? Your battery?
You need a strong battery to:
1. Spin the starter
2. Engage the Bendix
3. Provide voltage to the coil.
Tips on battery care and performance:
As the battery gets weaker, the first thing to fail is your spark. The more current you use to spin the starter, the less you have for the ignition. It doesn't really matter much if the battery is "fully charged" until you test it correctly. 4 Volts is an almost dead unit. Bench test under load and specific gravity must be tested. Your trusty local starter/alternator shop can bench test it on their special machine, usually at no charge –no pun intended. No matter what else you do, the battery must be fully charged. Cheap brands are prone to poor lifespans. The TSC and Wally World ones are the worst. 7 years is a good run for a 6V battery. Briefly in a nutshell, you want a GP-1 6V (12V = GRP 25 or GRP 35) AG battery -no Deep Cycle or RV/Golf Cart types. I suggest you invest in one of the better brands. Those would be DEKA, INTERSTATE, EAST PENN/DURACELL, or EXIDE. I'm not sure who makes the NAPA one but I've heard good things about it. Get at least a 550-750 CCA with the average cost at about $125.
A fully charged 6v battery should read about 6.3 - 6.6 volts. In order to get that charge level, your v/r must allow 7.2 volts to the battery. Specific gravity should be 1.24 - 1.28 on each cell. A hydrometer is used but your shop has the machine to test under load. Battery cables are important too. 6V cables are thick as your thumb due to current used and the ground is a braided flat strap. SEE DENNIS CARPENTER or nnalert. Clean all the grounds & the battery posts. 6V mantra: Clean, bright, and tight.
A float charger is VERY helpful; and NOT a trickle charger, but a float charger, like the DELTRAN Battery Tender Jr.® ™. It is a popular brand, available at Walmart, $30. A battery charger, even a "trickle" charger, left unattended will eventually boil out a battery. Connect the battery Tender to your battery when the tractor is idle for periods over a week. Constant Draining/Depleting and recharging the battery is the quickest way to ruin it.
BATTERY TENDER JR (6V) BY DELTRAN:
FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:
Tim Daley(MI)