The Massey Ferguson 135, a true icon of agricultural engineering, is celebrated for its reliability and simplicity. However, even the most dependable machines can experience hiccups, and the starter motor on the MF 135 is no exception. Understanding the common issues that plague these starters and knowing how to diagnose and address them can save you time, money, and a lot of frustration when you're trying to get your work done. After all, a tractor that won't start is a tractor that can't work, and that's a problem no farmer wants.

Why Won't My MF 135 Start? Let's Troubleshoot!

The sinking feeling when you turn the key and hear nothing (or worse, a troubling grinding noise) is familiar to many MF 135 owners. Before you resign yourself to calling a mechanic, let's explore some common reasons why your starter motor might be failing to crank the engine.

1. The Battery: The Obvious Culprit (But Don't Overlook It!)

It seems almost too basic to mention, but a weak or dead battery is the most frequent cause of starter motor issues. Don't just assume your battery is fine because the lights come on. Starter motors require a significant amount of current to operate, and a battery that's marginal for lights might be completely inadequate for cranking.

  • Check the voltage: Use a multimeter to check the battery voltage. A fully charged 12-volt battery should read around 12.6 volts or higher. Anything below 12 volts indicates a significant discharge.
  • Load test the battery: A load test simulates the draw of the starter motor and reveals if the battery can maintain voltage under load. Most auto parts stores offer free battery load testing.
  • Clean the terminals: Corrosion on the battery terminals can impede current flow. Clean the terminals with a wire brush and apply a thin coat of dielectric grease to prevent future corrosion.
  • Check the ground: Ensure the battery ground cable is securely attached to a clean, unpainted surface on the tractor frame. A poor ground connection can starve the starter motor of current.

2. Wiring Woes: Following the Electrical Path

The starter motor circuit is relatively simple, but breaks or corrosion within the wiring can cause problems.

  • Inspect the cables: Look for frayed, cracked, or corroded cables, especially the heavy-gauge cable running from the battery to the starter solenoid.
  • Check the connections: Ensure all connections in the starter circuit are clean and tight, including the solenoid connections and the starter motor terminals.
  • Test for voltage drop: Use a multimeter to measure the voltage drop across each cable and connection in the circuit while attempting to start the engine. Excessive voltage drop indicates resistance and a potential problem. A voltage drop of more than 0.5 volts across any single connection or cable warrants investigation.

3. The Solenoid: The Switch That Could Fail

The starter solenoid is an electromagnetic switch that engages the starter motor and connects it to the battery. A faulty solenoid is a common cause of starting problems.

  • Listen for the click: When you turn the key, you should hear a distinct "click" from the solenoid. If you don't hear anything, the solenoid might be faulty or not receiving power.
  • Test the solenoid: Use a multimeter to check for voltage at the solenoid's small terminal when the key is turned to the start position. If there's voltage but the solenoid doesn't engage, the solenoid is likely faulty.
  • Bypass the solenoid: Carefully bypass the solenoid by using a heavy-gauge jumper cable to connect the battery cable terminal on the solenoid directly to the starter motor terminal. If the starter motor engages, the solenoid is definitely faulty. Caution: Use extreme care when bypassing the solenoid. Ensure the tractor is in neutral and the parking brake is engaged.

4. The Starter Motor Itself: When the Motor's the Problem

If you've ruled out the battery, wiring, and solenoid, the problem likely lies within the starter motor itself.

  • Brushes: The brushes transfer electricity to the commutator, which causes the armature to spin. Over time, brushes wear down and need to be replaced.
  • Armature: The armature is the rotating part of the motor. Damaged windings or a shorted armature can prevent the motor from spinning.
  • Bendix drive (pinion gear): The Bendix drive engages the starter motor pinion gear with the flywheel ring gear. A worn or damaged Bendix drive can prevent the starter motor from engaging the engine.
  • Bushings/Bearings: Worn bushings or bearings can cause the armature to bind and prevent the motor from spinning freely.

5. The Flywheel: A Gear Too Often Overlooked

While less common, the flywheel's ring gear can be damaged, preventing the starter motor from properly engaging. This often manifests as a grinding noise when attempting to start the engine.

  • Inspect the ring gear: Visually inspect the flywheel ring gear for missing or damaged teeth. This requires removing the starter motor for a clear view.
  • Rotate the engine: Manually rotate the engine slightly and inspect the entire circumference of the ring gear.
  • Consider ring gear replacement: If the ring gear is damaged, it may need to be replaced, which is a more involved repair.

6. The Neutral Safety Switch: A Safety Feature Gone Wrong

The MF 135 has a neutral safety switch that prevents the engine from starting unless the transmission is in neutral. A faulty or misadjusted neutral safety switch can prevent the starter motor from engaging, even if everything else is working correctly.

  • Locate the switch: The location of the neutral safety switch can vary depending on the specific model and transmission type. Consult your tractor's service manual for the exact location.
  • Test the switch: Use a multimeter to check for continuity across the switch terminals when the transmission is in neutral. The switch should be closed (showing continuity) in neutral and open (no continuity) in gear.
  • Adjust or replace the switch: If the switch is faulty or misadjusted, it may need to be adjusted or replaced.

Diagnosing the Problem: A Step-by-Step Approach

Troubleshooting starter motor problems can seem daunting, but following a systematic approach can make the process much easier.

  1. Start with the battery: As mentioned earlier, the battery is the most common culprit. Check the voltage, load test the battery, and clean the terminals.
  2. Inspect the wiring: Visually inspect the cables and connections for damage or corrosion. Test for voltage drop in the starter circuit.
  3. Listen for the click: Listen for the solenoid click when you turn the key. If you don't hear anything, test the solenoid.
  4. Bypass the solenoid (with caution): If the solenoid is suspect, carefully bypass it to see if the starter motor engages.
  5. Inspect the starter motor: If the solenoid is working but the starter motor doesn't engage, the problem likely lies within the motor itself. Consider removing the starter motor for inspection and testing.
  6. Check the flywheel ring gear: If you hear a grinding noise, inspect the flywheel ring gear for damage.
  7. Verify the neutral safety switch: If all else fails, check the neutral safety switch for proper operation.

Repairing or Replacing: What's the Best Option?

Once you've identified the problem, you'll need to decide whether to repair or replace the starter motor.

  • Repair: Repairing a starter motor can be a cost-effective option if the problem is relatively minor, such as worn brushes or a faulty solenoid. Starter rebuild kits are available that include common replacement parts.
  • Replace: If the starter motor is severely damaged or worn, replacement is often the best option. New and rebuilt starter motors are readily available for the MF 135.

Preventative Maintenance: Keeping Your Starter Healthy

Regular maintenance can help prevent starter motor problems and extend the life of your starter.

  • Keep the battery charged: Regularly check the battery voltage and charge the battery as needed.
  • Clean the terminals and connections: Keep the battery terminals and electrical connections clean and tight.
  • Inspect the wiring: Regularly inspect the wiring for damage or corrosion.
  • Lubricate the Bendix drive: Periodically lubricate the Bendix drive with a light oil or grease.
  • Avoid prolonged cranking: Avoid cranking the engine for extended periods, as this can overheat and damage the starter motor.

Frequently Asked Questions

  • Why does my starter motor click but not turn over? The solenoid might be engaging but not making a good connection, or the starter motor brushes could be worn. Try tapping the solenoid with a hammer while someone turns the key.
  • What does a grinding noise when starting mean? This usually indicates a problem with the flywheel ring gear or the starter motor's pinion gear not engaging properly. Inspect both gears for damage.
  • How do I test the starter solenoid? Use a multimeter to check for voltage at the solenoid's small terminal when the key is turned to the start position. If there's voltage but the solenoid doesn't engage, it's likely faulty.
  • Can I rebuild my MF 135 starter motor myself? Yes, if you're mechanically inclined and have some experience with electrical repairs. Starter rebuild kits are available, but you'll need some basic tools.
  • Where can I buy a replacement starter motor for my MF 135? Replacement starter motors are available from tractor parts suppliers, auto parts stores, and online retailers.

A Reliable Start is a Productive Day

Addressing starter motor problems on your Massey Ferguson 135 doesn't have to be a daunting task. By understanding the common causes of these issues, following a systematic troubleshooting approach, and performing regular maintenance, you can keep your tractor starting reliably and ensure a productive day in the field. Remember to always prioritize safety and consult your tractor's service manual for specific instructions and recommendations.