Simple Tips and Tricks to Keep your N-Series Tractor Running

By Bruce Haynes with Chris Britton

These tips evolved from a series of notes I had scribbled in my tractor manuals, shortly after I bought my first 8N in 1999. I compiled 50 of these tips in 2006 and they were published in the N News. During the past six years, I’ve added 25 more and edited and revised a number of the original 50 tips. While I gleaned many of these tips from first-hand experience, I owe a great debt to many other N owners for sharing their wisdom with me over the years. Read on for the first 38 of my 75 simple tips and tricks!

Tractor part: the governor


1. The governor (right) has a long bolt and a short bolt – make sure that you put the short bolt on the top. If you put the long bolt on top, your next project will be to replace the timing gear (or, to replace the top bolt with a stud).

2. Front wheel dust seals are installed with the rubber toward the spindle and the metal toward the bearings. They are dust seals, not grease seals.

3. N tractors have a common sump for the rear end, hydraulic pump and transmission. There are three drain plugs under the tractor and one filler cap behind the gear shift. To change the fluid, start by removing the pipe plug under the rear end and move forward to the hydraulic pump and then the transmission. Use universal tractor fluid (UTF) that meets Ford spec M2C-134d (read the label). Or, you can use SAE 90W gear oil. CNH sells their oil as “Ambra G134.” Get the equivalent oil at TSC as Traveller brand GL1 or NAPA, Part No. 65-205.

Tractor part: the inspection plate

The inspection plate

4. To add just the right amount of hydraulic fluid, remove the bottom bolt from the inspection plate. Unless you just cleaned out the sludge in the pump base, it will only take about 4¾ gallons (not five) of the hydraulic oil. When the oil leaks out of the bolt hole, it has enough in it. If you have old or worn seals, any more fluid will leak past the seals and onto the brakes.

5. It is not necessary to add lead to the gas or use high-octane gas. This is a low compression (6.5:1) low hp (23 hp) engine with hardened valve seats.

6. Pick the weight of the engine oil by the condition of the engine (oil pressure) and the outside temperature. Many folks use 30w detergent all year. A straight weight oil is probably OK in a hot climate, but you will get excessive engine wear on startup in cold climates. (That’s one reason multi-viscosity oil was invented.) A worn engine is going to need a heavier weight oil to maintain oil pressure at operating speed and temperature. Many use 10w30, 15w40 or even 20w50. Some like the newer diesel rated oil because of the additives for the flat tappets and highly recommend Shell Rotella T 15-40. Increase the weight if the engine has low oil pressure. Switching to detergent oil is not going to loosen up the sludge in the engine.

Tractor part: the spark plug


7. Use Champion H-12 or Autolite AL437 plugs, as they run hotter than the original spec Champion H-10s.

8. The exhaust pipe clamp has a big side and a small side. The big side goes on the bottom.

Tractor part: the sediment bowl

Sediment bowl

9. Henry Ford was a frugal man and would never install anything on a tractor that was not essential to its operation. The fuel shut-off valve on the sediment bowl (right) is there for a reason – shut the gas off when you turn off the ignition key every time! If you forget and leave it on, and the needle valve or float in your carburetor is bad and the intake hose from the air filter is secured tightly to the carburetor, gas will flow from the carburetor into the intake manifold and into the engine, filling your oil pan with gasoline.

10. The NAPA part number for the sediment bowl gasket is 730-9506, but I have stopped using them because NAPA reduced the thickness. I use TSC part number 0237144. It is cork, so soak it in gas first.

Tractor part: the starter switch

Starter switch

11. Safety first! N’s have only two safety features: the starter switch (right) and common sense.

• If your tractor is sitting on frozen ground, BACK UP before trying to go forward. If the wheels are frozen to the ground and you let the clutch out in a forward gear, the tractor can flip over.
• Carry (or mount) a fire extinguisher and make sure you shake or tap the powder loose about every two months. A fire extinguisher can be easily mounted with radiator clamps or secured with velcro to the left side lift arm (the one without the leveling box).
• If you leave equipment attached to the three-point, lower it to the ground.
• Don’t wear loose clothing that could get caught up in the PTO.
• If the ramps on your trailer are steep, back onto it to avoid a flip-over.

12. When removing the hood from the 8N, first drain the gas out of the tank. Second, ask a neighbor for help. Disconnect the light wire and the fuel line. Remove the four bolts on the dash and the two on the dog legs and the radiator cap. Have saw horses ready to put it on.

13. If your N won’t start, you need to check for spark and fuel. Remove the bolt in the bottom of the carburetor As long as the fuel is turned on, you should see a steady flow of gas out of the carburetor. Check the spark, and keep in mind, it’s not the color of the spark, but the distance the spark jumps at the plug that gives you the information you want. It takes about 17kv to jump a 3⁄16” gap and 22kv to jump ¼” in the open air, so that’s why you need to use an old spark plug with the gap opened to a quarter inch. (You can also use a store bought plug checker.) Because it’s 14psi outside of the engine and about 90psi at a 6:1 compression ratio in the cylinders and compressed air creates electrical resistance, you need the 17-22kv to fire the plugs when the engine is running.

14. Think you have governor problems? There are three ways to check the operation of the governor. Set the throttle lever at its lowest point (engine idling) Then, slowly start tapping the throttle lever open. How far does the throttle move before the engine speeds up? Lack of low speed throttle response (like about one third of the throttle) is the classic symptom of a bad or out of adjustment governor. For the next test, put it in gear at about a quarter throttle, put your foot on both brakes and let the clutch out. The engine should throttle up as the governor arm opens the throttle plate in the carburetor to compensate for the load on the engine. Third test: with the tractor running, pull on the rod going to the carburetor to see if the governor pulls back. If that does not work, get out the I&T FO4 manual and check out the Adjusting Governor paragraph. Finally, before paying $200 or more for a new governor, pull it off and open it up. It could just need new balls and races.

15. Think your N needs an in-line gas filter? Think again. The three screens the tractor came with will work just fine if you keep them clean These tractors are 60 plus years old and they do require maintenance. If you find out that the screens are getting excessively dirty in a short period of time, then reline or replace the gas tank. No amount of in-line filters will help a rusty gas tank. A one piece steel line from the tank to the carburetor also provides safety and durability. Cutting that steel line and inserting a rubber hose around a hot exhaust manifold can be dangerous. And, because this is a gravity fuel supply system, an incorrect in-line filter can restrict fuel flow.

16. Got a problem with the lift arms dropping when the tractor is off or the clutch is depressed? You probably have a worn lift cylinder or piston (or both), a blown top cover gasket or a leaky pressure relief valve. Take the inspection plate with the dipstick off. Lift a heavy implement and look inside with the tractor running and the PTO engaged to see if you notice oil running from the top cover. If oil is running steadily from the top cover, chances are the lift cylinder needs to be rebuilt. It’s less likely, but possible, that the top cover gasket is bad. (It’s very difficult to detect the exact source of the oil leaking inside of the top cover while looking through the inspection port.) If no oil is running down from the top cover, look at the rear of the pump in the oil with the load still on it and see if you notice turbulence in the bottom (some movement of oil will be normal with the PTO shaft turning). You could have a weak pressure relief valve which will be detected by turbulence in the oil. To check for a slow leak, lift a heavy implement, turn the tractor off and put a ½“ clear plastic hose on the end of the valve. Stick the other end of the hose through the inspection port. With pressure in the pump, a bad valve will likely show some fluid in the hose.

Tractor part: the overrunning coupler

Overrunning coupler

17. There is a right and a wrong way to put the brake shoes back on. Take pains not to get the springs reversed or the adjusters on upside down. The adjusters have a “long” side and “short” side. The long side goes up on the left side wheel. The long side goes down on the right side wheel.

18. Always use an Over Running Coupler (ORC). An ORC (right) is a ratchet-like device that fits over the PTO shaft. It prevents the momentum in a heavy piece of turning equipment, like a bush hog, from pushing the tractor forward when you put in the clutch.

19. If you pull stumps or skid logs, hitch to the drawbar as low as possible or you are asking for a flip over. You can pull in reverse, using the front bumper or axle as the anchor point. Better still, hook up your blade to the three-point to avoid a flip over.

20. Adjust third-brush generators to produce no more than 11 amps MAX when starting, and 0-2 amps charge with lights on and running.

21. Open the fuel two full turns for normal operations, all the way out for the one-gallon reserve.

22. Have you adjusted your brake widget lately on your 9N/2N? The 9N and 2N (but not 8Ns) brakes have an adjustment wedge. By turning the wedge with a wrench, you can adjust the brakes.

23. If you do any work on the charging system on your N (remove the battery, disconnect the generator, etc.), you should re-polarize the generator, just in case the generator loses its residual magnetism when the battery is removed from the circuit. Unless you have a very early (and rare) 9N with a B circuit generator and voltage regulator, with the engine off, use a set of metal pliers to momentarily jump across the cutout. When it sparks, it is polarized. On the 8N, use a flat-blade screwdriver to momentarily touch the BAT and ARM terminals on the voltage regulator, again with the engine off. If you have the rare B circuit 9N, polarize it BAT to FLD, just like the NAA.

Tractor part: the radiator


24. The most common reason for an N to overheat is over-filling the radiator. Only add enough fluid to cover the core (check out tips 25 and 35). It is not actually over-heating, it is just spewing out the excess water. If the radiator is not over-filled, check for low coolant, a loose fan belt, debris in the radiator fins or a stuck thermostat. A bad water pump will usually squeak or leak. The fan belt should have ½” of flex at the mid-point – no more, no less. Unless you have a pusher fan, blowing out the radiator from the engine side is always a good idea.

25. Use a thermostat. If you don’t, the engine heats unevenly, which means it wears unevenly. A cool-running engine does not heat the oil sufficiently and you will get sludge build-up in the pan as a result.

Tractor part: the thermostat


The tractor came from the factory with a 160 degree thermostat. Sixty years ago, most antifreeze was alcohol-based, evaporating at temps above 160 degrees. You can use a 180 degree thermostat because a hotter-running engine is better on the oil. When installing the 160-degree thermostat in the upper radiator hose, the pointy end goes toward the radiator. Don’t worry if you put it in backwards. As soon as the coolant gets to 212 degrees, it will boil over, because installing the thermostat backwards blocks the upper hose!

26. While a worn shifter boot should be replaced, most moisture gets in the hydraulics from the draft spring, as well as normal condensation from operating.

27. Copper core spark plug wires have much better spark quality compared to automotive resistor wires.

Tractor part: the safety starter

The safety starter

28. Because of safety considerations, a properly functioning OEM starter interlock is worth the time and money to fix, even though it might be cheaper to simply bypass it with a new automotive starter switch. Without a starter interlock switch functioning properly, the tractor will start in gear. That is bad news.

29. Depressing the clutch when starting DOES reduce the starter drag especially when using thick transmission oil or in cold weather.

30. If you are doing a 12-volt conversion, it’s easier to use a 12-volt coil. That is a front coil with at least 2.5 ohms of internal resistance or a side coil with 3.25 ohms internal resistance. You can use the 6-volt coil with an additional external resistor, but most folks do not have the time or interest to accurately measure coil resistance to determine the necessary value of the additional resistor. (You always need the OEM ballast resistor with a front coil even if you use a 12 volt coil.)

31. Periodic lubrication of your 8N steering box is much, much easier than disassembling your steering box to replace the bearings. Look on the right side of the steering box, just above the proofmeter. Remove the bolt and stick a piece of wire with a “J” hook on the end in the bolt hole. Depending on the model of year steering box, you will find the hole going into the steering box. Get some plastic tubing, stick it on the end of your bottle of 90W gear oil (or, 140W outboard motor oil) and fill it up. No, you just can’t take the acorn hut off the top of the steering column and fill it from the top.

32. More lube tips: Service your air cleaner when you service your oil. Water does collect in there and can block airflow if it freezes. Also, the side mount distributors and the generator have an oil cup that needs a drop or two now and then.

33. If you have a new, round can coil for your 8N that does not say “BAT” and “DIST” on the top of it, just remember, for a POSITIVE GROUND tractor, it’s Positive Plus to Points (PPP) the “+” wire goes to the distributor.

34. The top hole on the three-point rocker was intended ONLY for light draft tillage equipment. DO NOT use it for plowing, mowing, disking, etc.

35. Always use the fan shroud. It allows the air to flow over the entire radiator.

36. If you need to remove the starter, always remember to have two nuts to place on the two long starter bolts as soon as you loosen them from the block. If you forget and the armature comes out of the starter housing, you will have to learn to hold the spring-loaded brushes back with toothpicks while you put the armature back in the housing.

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37. The screws holding the points to the plate in the distributor can wear out, causing the points to slip. Replace them with No. 8-32 x 3⁄16th screws. Make sure they do not extend under the plate and interfere with the advance weights.

Bruce Haynes

Bruce Haynes ‘the tips man’!

39. At a minimum, you need to have an operator’s manual for your N, as well as the I&T FO-4 shop manual. A parts catalog is a nice addition. (See our N-Store for all of your manuals and catalogs needs!)

38. If you forget and leave the ignition key on and the points just happen to be closed when the engine stopped turning, the chances are about 99 percent that the points are burned up. If you are very unlucky, so is the coil. Turn the key off.

(Bruce Haynes is a contributor to the N-News and grows 300 tomato plants for local farmers markets.)