Massey Ferguson 135 Starting Failure and Diesel System Diagnosis

[MikePhua]

The MF 135 and Its Agricultural Legacy
The Massey Ferguson 135 was introduced in 1964 as part of the iconic 100 series, quickly becoming one of the most successful utility tractors in history. Built with simplicity and durability in mind, the MF 135 featured a Perkins AD3.152 three-cylinder diesel engine, mechanical fuel injection, and a straightforward electrical system. With over 400,000 units sold globally, it remains a favorite among farmers, restorers, and collectors.
Its reputation for reliability is well-earned, but like any machine, age and wear can lead to starting issues. When an MF 135 refuses to run, the root cause is often buried in the fuel delivery system, electrical ignition, or air intake pathway.
Common Symptoms of No-Start Condition
When the MF 135 fails to start, operators typically report:

• Engine cranks but does not fire
  
• White smoke from the exhaust during cranking
  
• Fuel present at injectors but no combustion
  
• Glow plugs functioning but no ignition
  
• Engine fires briefly and dies
  

These symptoms point toward fuel delivery inconsistencies, compression loss, or timing misalignment. In one case, a farmer in Iowa experienced intermittent starting on his MF 135 during cold mornings. After inspecting the fuel system, he discovered air intrusion at the lift pump gasket.
Fuel System Architecture and Failure Points
The Perkins AD3.152 uses a mechanical inline injection pump fed by a lift pump drawing fuel from the tank. Key components include:

• Fuel tank and sediment bowl
  
• Lift pump with hand primer
  
• Inline injection pump
  
• Injector lines and nozzles
  
• Return line and banjo fittings
  

Common failure points:

• Clogged sediment bowl or fuel filter
  
• Air leaks at banjo bolts or lift pump diaphragm
  
• Weak lift pump unable to prime system
  
• Stuck injector nozzles
  
• Internal wear in injection pump plungers
  

To diagnose fuel delivery:

• Open bleeder screw on injection pump and prime until fuel flows without bubbles
  
• Crack injector lines and observe spray pattern during cranking
  
• Inspect fuel filter for contamination or water
  
• Replace lift pump if hand primer fails to build pressure
  

A technician in New Zealand resolved a no-start issue by replacing a cracked banjo washer at the filter head, which had allowed air into the system despite full fuel pressure.
Glow Plug and Cold Start System
The MF 135 diesel variant includes a cold start aid using glow plugs and a thermostart system. This system preheats the intake air and introduces a small amount of fuel into the manifold to assist ignition.
Key components:

• Glow plug in intake manifold
  
• Thermostart solenoid and fuel line
  
• Ignition switch with preheat position
  
• Battery and starter relay
  

If the glow plug fails or the thermostart fuel line is blocked, cold starts become difficult or impossible. To test:

• Remove glow plug and apply 12V briefly to check heating
  
• Inspect thermostart fuel line for blockage or leaks
  
• Verify voltage at glow plug terminal during preheat cycle
  
• Replace glow plug if resistance exceeds spec (typically 0.6–1.2 ohms)
  

In one restoration project, a vineyard operator in Chile replaced the glow plug and added a manual fuel primer to the thermostart line, improving cold start reliability during winter pruning season.
Compression and Timing Verification
Diesel engines require high compression to ignite fuel. If the MF 135 cranks but does not fire, compression loss may be the culprit. Causes include:

• Worn piston rings
  
• Valve leakage
  
• Head gasket failure
  
• Incorrect valve lash or timing
  

To verify:

• Perform compression test on all cylinders (target: 350–400 psi)
  
• Inspect valve lash and adjust to spec (Intake: 0.010", Exhaust: 0.012")
  
• Check timing marks on crankshaft and camshaft gears
  
• Ensure injection pump timing aligns with TDC on cylinder #1
  

A mechanic in Alberta diagnosed low compression on an MF 135 by observing excessive crank speed and white smoke. Replacing the head gasket and resetting valve lash restored normal operation.
Electrical System and Starter Integrity
Though diesel engines don’t rely on spark ignition, the starter system must deliver sufficient cranking speed. Weak batteries, corroded terminals, or a failing starter motor can prevent ignition.
Checklist:

• Battery voltage under load should exceed 10.5V
  
• Clean all ground straps and terminal connections
  
• Inspect starter solenoid for continuity
  
• Replace starter brushes if worn or pitted
  
• Use heavy-gauge cables to reduce voltage drop
  

In one case, a restoration shop in Georgia found that a corroded ground strap between the battery and frame caused intermittent cranking. Replacing the strap and cleaning the terminals resolved the issue.
Preventive Maintenance and Long-Term Reliability
To keep the MF 135 starting reliably:

• Change fuel filters every 200 hours
  
• Bleed fuel system after filter or line service
  
• Test glow plug annually and replace if weak
  
• Adjust valve lash every 500 hours
  
• Inspect lift pump diaphragm and banjo washers for leaks
  
• Keep battery terminals clean and cables tight
  

Use of winter-grade diesel and fuel conditioner can reduce cold start issues in low temperatures. Installing a block heater or intake heater improves ignition in sub-zero climates.
Conclusion and Recommendations
When a Massey Ferguson 135 refuses to start, the issue is often rooted in fuel delivery, compression, or cold start systems. With methodical diagnosis and attention to detail, the tractor can be restored to reliable operation without major overhaul.
Recommendations include:

• Prime and bleed the fuel system thoroughly
  
• Test glow plug and thermostart fuel delivery
  
• Verify compression and adjust valve lash
  
• Inspect lift pump and banjo fittings for air leaks
  
• Maintain clean electrical connections and strong battery output
  

With proper care, the MF 135 continues to serve as a dependable workhorse—ready to plow, haul, and grade with the mechanical resilience that made it a legend in agricultural history.