This is a continuation of our series on Cultivator Tractors
Written by Joseph M Hannan , Production Instructor
Center for Arkansas Farms and Food
05.01.2025
Edited by Luke Freeman
Bringing it home
So you went fancy and purchased a diesel offset cultivator tractor. Instead of a 40 to 60 year old tractor you have a 30 to 40 year old tractor with electronics from the 1980s! Fortunately, those electronics can easily be replaced…but I’m getting ahead of myself.
There are a lot of similarities between old gas and diesel tractors in regards to refurbishing them and making them reliable. The post on Refurbishing An Old Gas Tractor covers a lot of details in depth so we won’t rehash everything here.
In summary, start with your standard precheck and inspection:
- Check all fluids and top off as needed
- Clean and degrease so you can see any and all leaks
- Then go out to a field and work the tractor hard to find all leaks and problems with the tractors. This is a necessary step to identify what needs to be fixed before putting the tractor to daily use.
Once again, the goal with the precheck is to identify any and all problems that need to be service and repaired.
Fluids
Start by changing all of the fluids. This includes the engine oil, engine coolant, steering box oil, hytran (rear differential, transmission, and hydraulics) oil, and drop axles as well as all filters. I think most or all of the Gen 2 and Gen 3 cultivator tractors will have one fluid for transmission, hydraulics, and differential…one drain and one refill. Your service guide and manual will show you where all of the filters, drains, and fill ports are located. I know on the Kubota L245 that the hydraulic filter is internal, located on the driver’s side, way back near the axles. There are two bolts and a cover that needs to be removed…it’s a tight fit even for me to reach…and it doesn’t come out all the way without removing the fender. Ugh!
Don’t forget to change the diesel fuel filter but don’t worry about re-priming the system just yet. More on the fuel system shortly.
Like gas tractors, grease everything and if a zerk won’t take grease, use the Grease Buster by LockNLube and solvent or diesel to clean out the zerks and joint.
Diesel Injection System
Things get much harder from here! Let’s move onto the fuel system.
Glow plugs are a heating element on diesel tractors that warm the combustion chamber. They make it easier to start older diesel tractors when temperatures are cold. In my experience, they are necessary to get a tractor of this vintage started on cool mornings. The glow plugs are probably original and should be replaced…at $15 each ($45 total), it’s a cheap repair. However, you also want to check the switch that turns them on…there is a good chance that it too needs to be replaced.
The next item on the to-do list is to replace the fuel injectors. Again, they are probably original and in need of cleaning or replacement. These are about $100 a piece so there is a fair cost involved here but new fuel injectors should help the tractor start and run efficiently, run better, and preserve the life of the engine as diesel injectors are a wear item.
It is safe to assume the glow plugs and injectors on an older tractor are original and need to be replaced. The CAFF Kubota L245H starts and runs much better since these parts were replaced. Credit Joe Hannan
Finally, you will want to check all of the fuel supply lines from the tank to the injection pump. If they are rubber, then consider replacing them and installing new clamps. The old rubber and clamps might allow air to get into the fuel system which can make it difficult to start the tractor. Fuel line and clamps can be purchased from any auto store for a few dollars
Overall, looking at the fuel system on a diesel tractor, there are a few key places that will give you headaches day in and day out. The fuel tank shutoff valve probably leaks. Its probably just a few seals that need to be replaced or replace the whole valve. The rubber fuel lines and clamps probably all leak as well…this is a simple repair and easiest to do while you are repairing the leaky fuel tank valve. Finally, change the injectors and fuel filter. These couple of things should make it a LOT easier to start the tractor, reliably!
The shutoff valves on old tractors tend to leak as do old fuel lines. This allows air into the fuel system making it difficult to start the tractor. Credit Joe HannanNext up is the electrical system. All in for CAFF to make fuel system repairs on our Kubota L245H, less than $500 and a day of work.
Diesel Electrical System
Back to the glorious 1980’s electronics!
In all fairness, the electrical system on the generation 2 and 3 offset cultivators is still fairly simple and easy to repair similar to the Farmall 140. It may even be easier.
No spark plugs means a MUCH easier electrical system overall compared to gas tractors. However, we now have safety devices that can cause some headaches. So just like gasoline tractors, battery and positive and negative battery cables should be replaced. Electrical gremlins start here!
Next, connect a volt meter to the frame and the 12volt switch on the starter (the small wire). Turn the tractor key to the “on position” and IF there is a clutch safety switch (such as found on the Kubota L245H and I am pretty sure the JD 900HC and very likely all of the other Gen 2 and 3 tractors) depress the clutch. Compare the DC voltage at the switch with just the battery. It should be the same if you have good electrical conductivity through the key and starter circuit. If you have a voltage loss, you need to clean all the wire terminals from the key switch, to the starter switch, the clutch safety switch, and to the starter. These are probably original wires and switches and are getting corroded. A little sandpaper or emery board on the switches goes a long way. Then clean the wire terminals or replace the wire. This is a little more tricky as there are now wire harnesses and a lot more to the wire system than the old Farmall gas tractors. Take your time, track the wires, and clean as you go. If the electrical system is really bad, you can make a new harness and replace all of the wire. These systems are not complex and should only take day to do.
You can also do an alternator test at this point as well to verify that the alternator is charging the battery. Now obviously with a diesel tractor, you could just start it each time with a battery charger and remote starter switch if the battery and alternator are dead. But, this discussion is about daily reliability and having a tractor that will start anytime, every time!
Fortunately, with diesel tractors, key switches, starter switches, cables, etc are all easily found…either stock or aftermarket stuff. As you are cleaning connections, replace as needed.
Fluids Standardization
Each tractor manufacturer has specific guidelines for fluids (engine oil, gear oil, transmission oil, engine coolant etc) that are to be used for their tractors. Fortunately, new fluids today essentially meet or exceed fluids that were available 30 to 60 years ago so in practice you should be able to have a core set of fluids used across an array of tractors. This minimizes the fluid expenses and reduces error when topping off fluids mid-season. For example, CAFF has a New Holland Workmaster 75, a Kubota L245H, and a Farmall 140. With one new modern tractor and two older tractors, we have standardized all fluids to meet the requirements of the New Holland. For us, we will use the same New Holland engine oil, New Holland transmission/hydraulic oil, generic gear oil, and generic coolant across all three tractors. This minimizes the variety of fluids we must keep on hand, allows us to buy in bulk, and reduces the risk of damage due to an incorrect fluid being used somewhere.
There are a lot of people that argue with this approach and claim any deviation from manufacture oil specifications will cause spontaneous combustion and complete drivetrain failure. This is unlikely the case. I cannot speak for all manufacturers, but Kubota, New Holland, and CASE IH appear to have compatible engine oil and transmission/hydraulic fluid.
Coolant is the one engine fluid that you don’t want to mix colors or types. The seals in engines are designed for use with specific coolants. Using a non-specified coolant could cause engine seals to decay causing leaks or damage to your engine.
Other Items
Of course, if you have bigger issues such as clutch, brake, hydraulic pump, or fuel pump issues, those too will need to be sorted. You cannot have a well running tractor without sorting those issues. Ideally, don’t buy a tractor that has any of those issues.
Diesel Tractor Summary
Getting an old diesel cultivator tractor running, reliably, takes some time and work. The key on an old and old diesel tractor is servicing the fuel system and ensuring quality electrical connections the starter and glow plugs. Service those items and you are likely in pretty good shape unless the tractor has serious repairs that are needed.