6 Most Common Kubota L3901 Problems (Plus Effective Fixes)

The Kubota L3901 is a heavy-duty tractor with excellent efficiency, exceptional durability, and increased comfort. Although these tractors are sturdy and robust, they have several downsides you should be aware of. The leading Kubota L3901 problems are hard starts, regeneration problems, PTO complications, overheating, steering issues, and electrical problems.

Does your Kubota L3901 break down frequently? Or perhaps you want to purchase an L3901 tractor. Read on as we dissect common L3901 problems and how to troubleshoot them.

Starting Problems

Clogged fuel filters, damaged injection pumps, aeration, and closed supply valves are the leading causes of Kubota L3901 starting problems.

Clogged fuel filters reduce the fuel reaching the engine and the oil pressure, leading to starting difficulties. Filters collect fuel residue and block after prolonged use. To fix this issue, clean all the residue off the filters. 

Faulty or clogged injection pumps don’t push adequate fuel into the engine’s cylinder. This strains and stresses the engine. Regularly monitor the fuel injectors, clean them when clogged, and replace them if damaged.

Excess air in the fuel tank reduces the fluid’s pressure, making it incapable of reaching the engine. Open the fuel tank and let it bleed for a while. Close it after all the bubbles have come up.

You should also check for faulty lines, gaskets, and seals, as they are the primary culprits for letting air into the system. Replace them immediately to fix this issue.

Closed supply valves hinder fuel from flowing through the system. Ensure that all supply valves are opened all the way to curb this problem.

Regen Problems

Kubota L3901 regeneration problems result from insufficient oil, incorrect oil, faulty sensors, clogged Diesel Particulate Filters, and short drives.

The regeneration process won’t start if the fuel tank is less than a quarter full. Regularly check the fuel levels and refill the tank to the appropriate levels for smooth regeneration.

Using the wrong, poor-quality oil hinders the regeneration process. Low sulfur and low ash diesel engine oils are the most appropriate for effective regeneration.

The engine relies on the sensor to trigger the regeneration procedure. Faulty sensors don’t spark the engine, stopping the DPF process. Check if the sensors are in tip-top condition and replace them if not.

Although DPFs clean themselves, they tend to clog due to the ash in diesel engine oils. After prolonged use, the ash residue completely blocks the filters, making regeneration difficult. Regularly clean the DPF filters to curb these Kubota L3901 problems.

To clean the DPF filters, detach them from the tractor by removing the grills and plates beside them. Ensure you safely place the screws, bolts, nuts, and o-rings, so you don’t lose any.

Start by placing them in a high-pressure cleaning cabinet. The compressed air will help dislodge the ash blockage. Repeat this step until all cells are clean. Proceed to rinse the filters with water. Using a high-pressured faucet or hose is the most efficient way to do this. You could use chemical cleaners like fuel additives if you don’t want the hassle of detaching DPF filters.

Short-distance drives don’t give the engine enough time to warm up. High temperatures are essential in converting soot particles into carbon dioxide during regeneration. Stick to long drives to curb these issues. If you have no choice, keep the tractor running while charging for effective regeneration.

Kubota L3901 PTO Problems

Kubota L3901 PTO problems arise when the shaft turns when not engaged, the shaft refuses to turn even when engaged, and the system ultimately declines engagement.

The PTO shaft may turn when not engaged due to a faulty clutch pack, a defective brake disc, and a poor control valve adjustment. PTO clutch packs overheat and wear out after prolonged use. Monitor them closely and replace them at first sight of aging.

 A faulty brake disc doesn’t stop the clutch when needed to. Replace these to avoid Kubota L3901 clutch problems and improve PTO efficiency.

Wrong PTO control valve adjustments only allow partial floating and engaging. This results in the PTO misbehaving. Always confirm if the control valves are correctly adjusted before starting work.

The PTO shaft may refuse to turn even after engaging the system because of a bent clutch hand lever or damaged linkages.

PTO rear box linkages are crucial for efficient engagement. If faulty, turning the shaft may be problematic. Replace damaged linkages with new ones to fix this issue.

You should also check if the hand lever is in its best condition, as it easily bends when overloaded, causing PTO issues. Stick to the recommended PTO load to avoid harming the hand lever.

The PTO may refuse to engage due to faulty internal components like rings. Rings are easily damaged when tackling intensive jobs without a slip clutch, which absorbs engine braking force. Regularly monitor these tractor parts if you frequently work on large yards and replace them when damaged.


Clogged radiators and insufficient or old coolant are the leading causes of overheating in your Kubota L3901.

Radiators facilitate engine cooling by letting out the hot air. Radiators have heat sinks, which quickly collect dirt, leading to malfunction. Regularly vacuum or blow the radiators with high-volume, low-pressure air to enhance their efficiency and prevent damage.

Sufficient coolant is crucial for engine cooling. Regularly refill the cooling fluid to prevent these Kubota L3901 problems.

Old coolant has lots of dirt and residue build-up, making it heavy to flow through the system. Flush out old, contaminated coolant and refill it with a new one.

Steering Issues

Kubota L3901 steering problems include excessive play, heavy steering, or left or right wheel wandering. Hard steering in your tractor might arise due to low tire pressure, worn-out valves, and insufficient oil.

Smooth steering requires adequate tire pressure. Low tire pressure exerts lateral and forward drag effects on the steering, making it slippery. Always ensure the wheels have the appropriate pressure for steady steering.

Worn-out valves leak, reducing the pressure required for smooth steering. Regularly monitor these steering parts and replace them if faulty.

Insufficient oil provides inadequate force for steering. Refill the steering fluid immediately if it reduces past the appropriate level.

Your tractor’s steering may have excessive play because of a worn-out shaft, faulty steering box components, and broken linkages. Replace defective shafts, steering box parts, and linkages to solve this problem.

Wheels may wander from right to left due to deflated tires or faulty steering components. Ensure the wheels are appropriately inflated for smooth steering. You should also check all steering components and replace all defective ones.

Electrical Problems

If your L3901 tractor experiences charging difficulties and a problematic starter motor, it may have electrical problems.

Bad wiring, poor connections, faulty belts, and corroded cables and terminals are the primary causes of difficult charging. Low quality and incorrect wiring hinder smooth electric flow. Replace these immediately for better operations.

Loose alternator belts don’t produce enough speed to generate sufficient power to charge the battery. Monitor these belts and replace them when they show aging or wearing out signs.

A wrong or poor connection pushes only twenty-five percent of the total current, leading to charging problems. Always ensure that all cables are appropriately connected for reliable and fast charging.

Corroded cables and terminals can’t transfer electric current from the power source to the battery. Clean these or replace them immediately if irreparable.

Kubota L3901 starter motors may turn slowly or refuse to crank due to low battery voltage, faulty wires, disconnected cables, or a faulty battery.

To curb these inconveniences, always ensure the battery’s voltage is above twelve before setting off and replace broken or worn-out wires immediately. Connecting all cables properly and replacing a damaged, old battery also solves this problem.

Are Kubota L3901 Problems a Deal Breaker?

Although Kubota L3901 tractors have a few issues, these tractors have wonderful features and get the job done. Most Kubota issues aren’t severe, but for your peace of mind, Kubota offers a one to two years warranty on their tractors. Follow the troubleshooting guide above whenever Kubota tractor problems arise.