About the Massey Ferguson MF135

Massey Ferguson developed a wide range of agricultural vehicles and have a large share in the market across the world especially in Europe. The next big selling model was the MF135, widely popular because of its reliability and power compared with other tractors at the time. This was the first model in the MF 100 series. The Massey Ferguson 135 is a popular tractor. In fact it is one of the most popular tractors for vintage and classic enthusiasts.

Massey Ferguson MF135 and MF148 Tractor factory workshop and repair manual

Short version: the clutch release (throw‑out) bearing lets the clutch pressure plate stop clutching when you press the pedal. On an MF135 M148 you must drop/slide the gearbox back off the engine to get at it. Replace the bearing, inspect/replace the clutch disc/pressure plate and pilot bushing while you’re in there, clean and reassemble with proper alignment and torque, then adjust pedal free play. Below is a beginner‑friendly, step‑by‑step guide with full descriptions of every component, why the repair is needed, how the system works, what can go wrong, and practical tips.

SAFETY FIRST
- Work on level ground, wheels chocked, parking brake on and battery disconnected.
- Use appropriate lifting gear: a transmission jack or engine hoist and a second person. The gearbox is heavy; do not rely on hand jacks alone.
- Wear safety glasses, gloves and steel‑toe boots if available.
- Mark parts and take photos to aid reassembly.
- If you’re uncomfortable with removing the gearbox, get help from a shop.

THEORY / HOW THE SYSTEM WORKS (analogy)
- Think of the clutch as a sandwich between the engine flywheel and the gearbox input shaft. The clutch disc is the filling, gripped by the pressure plate (the top slice). When gripped, engine power passes through to the gearbox; when released the disc is free and power is interrupted.
- The pressure plate has fingers (or diaphragm) that push the plate against the disc. The release (throw‑out) bearing is the small round bearing that presses on those fingers from the clutch fork when you press the pedal. When you press the pedal the fork pushes the bearing against the pressure plate fingers; the bearing lets the fork slide while the pressure plate fingers rotate with the engine.
- Analogy: the pressure plate is a clamp holding the disc; the release bearing is the bouncer that pushes the clamp’s release lever so the clamp opens. If the bearing is noisy or stuck, the bouncer isn’t working, so you can’t release the clamp smoothly.

KEY COMPONENTS — names and what they do
- Flywheel: bolted to engine crankshaft. Smooth or machined face that the clutch disc contacts. Also holds starter ring gear.
- Clutch disc (friction plate): splined to the gearbox input shaft; transmits torque when squeezed between flywheel and pressure plate.
- Pressure plate (clutch cover): bolts to flywheel; springs/diaphragm provide clamping force.
- Release (throw‑out) bearing: bears on the pressure plate fingers. Slides on the gearbox input shaft (or sleeve) and transfers motion from clutch fork to pressure plate.
- Clutch fork (release lever): pivoting lever actuated by the pedal linkage that pushes the release bearing.
- Pivot ball/pin or fulcrum: pivot point for the fork inside the bell housing.
- Pilot bearing/bushing: in the center of the flywheel/crank or in the end of the crank; supports the input shaft nose and centers the clutch disc. Often a replaceable bronze bushing on MF tractors.
- Bell housing: the shell that connects gearbox to engine and encloses the clutch.
- Gearbox/input shaft: splined shaft that the clutch disc slides on; input shaft transmits power into transmission.
- Clutch release sleeve (some MF parts): sometimes the bearing runs on a sleeve or collar; inspect any sleeves for wear.
- Linkage: rods and levers between clutch pedal and fork (Massey uses mechanical linkages on MF135).

WHY THE REPAIR IS NEEDED (symptoms)
- Loud, growling, rumbling, or squealing noise when clutch pedal is depressed.
- Noise only while pedal is down (classic worn bearing symptom).
- Vibration or judder when pressing pedal.
- Sticking or rough clutch release.
- Clutch does not disengage (hard to change gears).
- Pedal feels rough or binds.
If these appear, the release bearing or its sleeve/pivot is often worn or failing. Because the bearing sits where the gearbox must move, access requires dropping the gearbox.

TOOLS & PARTS
- Tools: full metric/Imperial socket set, combination wrenches, breaker bar, torque wrench, screwdrivers, wire brush, pliers, punch/soft hammer, clutch alignment tool (or threaded bolt/DIY wooden dowel), pilot bearing puller or suitable driver, puller for any retaining rings, transmission jack or sturdy floor jack and support, engine support/hoist if needed, pry bars, gasket scraper, sealant, rags, brake cleaner.
- Safety: wheel chocks, jack stands, gloves, eye protection.
- Parts: correct MF135 replacement release bearing (OEM or good aftermarket), pilot bearing/bushing, inspect/consider replacing clutch disc and pressure plate as a set, pivot ball/pin and spring(s) if worn, any sleeve/collar if fitted, new gearbox-to-engine gasket or sealant, new bolts if any are damaged.
- Consumables: light high-temp grease (only where specified), gasket sealant if needed, anti-seize for bolt threads in some areas (use sparingly), brake cleaner.

PREP: BEFORE YOU START
- Drain gearbox if required and/or disconnect PTO shafts/prop shaft. For MF135, remove driveshafts, linkages and any cross‑members blocking gearbox removal.
- Label or photograph linkages and wiring.
- Get a helper and a transmission jack ready.

STEP-BY-STEP REMOVAL (general MF135 approach)
1. Disconnect battery negative.
2. Remove bonnet and any obstructing panels to access gearbox top and sides.
3. Remove clutch linkage at the pedal and at the fork. Unbolt any return springs and note positions.
4. Remove propshafts and PTO drive where they connect to gearbox; remove mudguards/brackets as needed.
5. Support the gearbox with a transmission jack or floor jack and wood blocks. Support engine with an engine support if needed to prevent sagging.
6. Remove drivetrain connections: gear lever linkage rods, speedometer cable, hydraulic lines if attached to housing, electrical connectors.
7. Unbolt bell housing/gearbox-to-engine bolts. On MF135 there are 6–8 bolts around the bell housing. Keep track of bolt locations (lengths vary).
8. Carefully slide the gearbox rearward (away from engine) until the input shaft clears the clutch assembly. Pull the gearbox straight back on the jack — the clutch assembly will remain bolted to the flywheel. Have a helper steady the engine side or transmission.
9. Once gearbox is free, support it so it won’t tip. Inspect the input shaft and splines for wear.
10. With gearbox off, you’ll see the clutch pressure plate bolted to the flywheel and the release bearing sitting on the fork or collar area.

REMOVING THE RELEASE BEARING ASSEMBLY
11. Remove clutch fork: pull it off its pivot ball/pin. Note orientation. The release bearing may be clipped or sitting on a sleeve that’s removable.
12. Remove the release bearing from the fork or input sleeve. Some MF bearings have a carrier/retainer ring—remove any C‑clip or retaining hardware.
13. Remove pilot bearing/bushing from the flywheel/crank if equipped — use puller or press. MF tractors often have bronze bushing; replace it if worn.

INSPECT COMPONENTS (critical)
- Release bearing: replace if noisy, rough, or has axial play. Even if it looks okay, replace when gearbox is out—cheap insurance.
- Clutch disc: inspect friction surfaces for glazing, oil contamination, worn splines, or rivet exposure. If >50% worn or contaminated, replace.
- Pressure plate: check springs/diaphragm fingers for wear or unevenness. If fingers are damaged or heat‑spotted, replace.
- Flywheel: check face for scoring, heat spots, cracks. Resurface if glazed or uneven; replace if cracked.
- Input shaft splines and pilot bore: check for wear or scoring. Replace or recondition if badly worn.
- Clutch fork pivot and pivot ball: check for wear and bushings; replace if worn.
- Bell housing: check dowel pins for damage; ensure they aren’t stuck.

INSTALLATION — RELEASE BEARING & REASSEMBLY
14. Clean mating surfaces (flywheel, bell housing) with brake cleaner; do NOT get grease on friction surfaces.
15. Install new pilot bearing/bushing (lightly oil if required by manufacturer).
16. If the release bearing is the sealed type, do NOT pack it with grease. If it has a grease point or a specified grease area, apply a light smear only to the contact surfaces recommended by the manual. Typically you may lightly grease the outside that contacts fork, but not the inner race where it contacts rotating surfaces. Many throw‑out bearings are pre‑lubed and sealed — leave them as is.
17. Fit new release bearing onto fork or sleeve per original orientation; secure any retaining clips.
18. Refit clutch fork onto pivot ball/pin. Make sure it seats firmly and moves smoothly. Grease pivot points lightly if specified.
19. Check that the bearing slides freely and that it contacts the pressure plate fingers squarely when the fork is actuated.
20. Refit gearbox: align gearbox input shaft with the clutch disc spline. Use a clutch alignment tool inserted through the pressure plate and disc into the pilot bushing to center the disc. This is critical — think of the disc as the donut and the alignment tool as the rod that keeps the hole centered so the gearbox slides into it.
21. Carefully slide gearbox forward until it mates with engine block and bell housing. Ensure dowel pins align. Do not force; if it binds, back off and re‑align.
22. Tighten gearbox‑to‑engine bolts hand tight, then torque in a crisscross pattern to manufacturer specs. (If you do not have the MF manual: torque the bell housing bolts to a medium value and check a manual later; typical gearbox bolts on small tractors are often 40–60 Nm / 30–45 ft‑lb, but check exact specs.)
23. Reattach linkage, speedometer cable, PTO/propshaft, and other removed components.
24. Reconnect clutch linkage and set pedal contact as described below.
25. Refill gearbox fluid if drained.
26. Reconnect battery.

CLUTCH ADJUSTMENT / FINAL CHECKS
- Clutch pedal free play: for many Massey tractors, set free play (movement before release fork begins to move) to roughly 1/4"–1/2" (6–12 mm). Adjust rod so there’s a small amount of play; exact is in the service manual. Ensure linkage is secured and returns freely.
- With engine off, have an assistant press the clutch pedal and watch the release bearing: it should move straight forward and back, not tilt.
- Start engine and check for abnormal noises when pressing clutch pedal. Ensure gear changes are smooth with engine running at low idle (take care in area).
- Test drive and re‑check torque on bolts after initial run.

WHAT CAN GO WRONG (and how to avoid it)
- Contaminating clutch disc with grease/oil: never put grease on friction surfaces. If contaminated, replace disc and clean surfaces thoroughly.
- Misaligning clutch: if gearbox won’t slide in easily, the disc is likely off‑center. Use alignment tool.
- Damaging input shaft splines: forcing gearbox can damage splines; realign and ease in.
- Broken dowel pins/stripped bolts: mark and support heavy parts, use proper tools and torque. Replace any damaged hardware.
- Not replacing pilot bearing: worn pilot bushing can cause input shaft misalignment and new bearing wear.
- Over‑ or under‑torquing bolts: use a torque wrench and manual specs.
- Improper lubrication of release bearing or fork pivot: follow bearing instructions—some bearings are sealed and must not be greased; pivot points may accept a light smear of high‑temp grease.
- Forgetting to refill gearbox oil or reconnect linkage: double‑check everything before test run.
- Injury from dropping gearbox: always use a jack and helper.

TROUBLESHOOTING AFTER INSTALL
- Noise only when pedal down: likely release bearing contact or fork geometry — check bearing orientation and seating.
- Grinding on engagement or difficulty shifting with pedal depressed: misalignment or clutch not fully releasing — recheck free play, fork pivot and bearing seating, pilot bushing.
- Slipping/clutch burns: if new bearing noise is gone but clutch slips, clutch disc/pressure plate likely worn or contaminated — replace.
- Harsh pedal or low engagement: check pedal linkage, return springs and correct adjustments.

MAINTENANCE AND GOOD PRACTICE
- When the gearbox is off, always inspect and often replace wear items (bearing, pilot bushing, fork pivot, clutch disc and pressure plate) as a set if in doubt — saves labour later.
- Keep work area clean to avoid contaminating clutch parts.
- Record bolt locations and torque values for future reference.

ESTIMATED TIME & DIFFICULTY
- A competent non‑specialist with proper tools and a helper: 4–8 hours. First time may take longer.
- Difficulty: moderate to high mainly because of the heavy gearbox removal and need to align parts precisely.

Final practical tips
- Take multiple photos before disassembly.
- Label bolts and parts as you remove them.
- Store the clutch disc away from grease and oil.
- If the flywheel face looks questionable, have it checked/resurfaced by a machine shop.
- Buy the correct MF135 M148 parts by OEM part numbers where possible.

That’s the full procedure in practical detail. Replace the bearing, inspect pilot bushing, clutch disc and pressure plate; clean, align and torque correctly; adjust pedal free play; test carefully.
rteeqp73

### Crankshaft Position Sensor Replacement on Massey Ferguson MF135 M148 Tractor

#### Tools Needed:
1. **Socket Set** (Metric and SAE)
2. **Wrench Set**
3. **Screwdriver Set**
4. **Torque Wrench**
5. **Pliers**
6. **Multimeter** (for electrical testing)
7. **Shop Rag** or **Paper Towels**
8. **Safety Glasses**
9. **Gloves**

#### Safety Precautions:
1. **Disconnect the Battery**: Always disconnect the negative battery terminal to prevent electrical shock or short circuits.
2. **Work on a Level Surface**: Ensure the tractor is on a stable, level surface to prevent it from rolling.
3. **Use Personal Protective Equipment (PPE)**: Wear gloves and safety glasses to protect against dirt and debris.
4. **Allow Engine to Cool**: Ensure the engine is cool before starting work to avoid burns.

#### Step-by-Step Procedure:

1. **Locate the Crankshaft Position Sensor**:
- The sensor is typically located near the crankshaft on the engine block. Refer to the service manual for the exact location.

2. **Remove Obstructions**:
- Depending on the tractor's configuration, you may need to remove components such as the air intake or covers to access the sensor.

3. **Disconnect the Electrical Connector**:
- Carefully unplug the electrical connector from the crankshaft position sensor. Use pliers if necessary to avoid damaging the connector.

4. **Remove the Sensor**:
- Using the appropriate socket/wrench, unscrew the bolts or screws holding the sensor in place.
- Gently pull the sensor out of its housing. Be cautious not to damage the surrounding components.

5. **Inspect the Sensor and Connector**:
- Check for any signs of wear, corrosion, or damage on the old sensor and the connector. Clean any debris in the area.

6. **Install the New Sensor**:
- Place the new crankshaft position sensor into the housing. Ensure it fits snugly.
- Tighten the bolts/screws to the manufacturer's specified torque settings using a torque wrench.

7. **Reconnect the Electrical Connector**:
- Plug the electrical connector back into the new sensor. Ensure it clicks into place securely.

8. **Reassemble Any Removed Components**:
- Reinstall any components that were removed to access the sensor, ensuring all bolts/screws are properly tightened.

9. **Reconnect the Battery**:
- Reconnect the negative terminal of the battery.

10. **Test the Sensor**:
- Start the engine to ensure it runs smoothly. Use a multimeter to check the signal output from the sensor if necessary.

#### Common Pitfalls to Avoid:
- **Forcing the Sensor**: Do not force the sensor into place; it should slide in easily. Forcing can cause damage.
- **Neglecting Torque Specs**: Always use a torque wrench to avoid over-tightening, which can damage the sensor or housing.
- **Ignoring Electrical Issues**: If the new sensor does not resolve the issue, check the wiring and connectors for damage or corrosion.
- **Not Cleaning the Area**: Ensure the area around the sensor is clean before installation to prevent debris from entering the engine.

#### Replacement Parts:
- Always use OEM or high-quality aftermarket parts that meet specifications for the MF135 M148. Ensure the part number matches the original sensor to avoid fitment issues.

This procedure will help you successfully replace the crankshaft position sensor on a Massey Ferguson MF135 M148 tractor with safety and efficiency.
rteeqp73

Summary: Replacing the drive belt(s) on an MF135/M148 is a straightforward mechanical job if you follow safety steps and check the pulleys and tensioning system while you’re at it. Below I explain what every component does, why the repair is needed, what can go wrong, and give a clear, step‑by‑step procedure written for a beginner mechanic.

Important safety first
- Work with the engine OFF, key out, and battery negative disconnected.
- Let the engine cool completely before touching the fan, water pump, or other hot parts.
- Chock wheels and set parking brake.
- Wear gloves and eye protection.
- Don’t put your fingers between a belt and a running pulley.

What you’re dealing with (components and what they do)
- Engine crankshaft pulley (harmonic balancer on some machines): main drive pulley that puts power into the belt.
- Fan (direct- or hub-mounted): pulls air through the radiator to cool the engine. Sometimes mounted on the water pump or crank pulley.
- Water pump pulley: driven by belt to circulate coolant.
- Generator or alternator and its pulley: charges battery / powers electrical system. Older MF135s often have a generator; some conversions use an alternator. Their mounting usually pivots.
- Idler pulley(s) and/or tensioner: maintain correct belt tension and routing. Older tractors may use a manual adjuster (pivot + long adjustment bolt) rather than an automatic tensioner.
- Belt (V-belt or multi-rib/serpentine): rubber element that transmits power from the crank to accessories. On classic MF135 tractors the original design uses V-belts; some later or modified tractors may have a multi‑rib belt or a single conversion belt.
- Mounting/adjustment bolts, pivot bolt, locknuts: hold and adjust the generator/alternator or idler.

How the system works — the theory (simple)
- The engine crank pulley is the “engine’s shoe” rubbing on a rubber band (the belt). The crank turns the belt, the belt wraps pulleys and makes the water pump, fan, and generator/alternator spin. If the belt is loose, it slips — just like a loose bicycle chain won’t push the wheel well. If the belt is too tight, it stresses bearings (wheel bearings → alternator/water pump bearings). Tension must be correct for power transfer and component life.

Analogy: imagine the belt as a bicycle chain and the pulleys as sprockets. If the chain is slack, it skips and makes noise; if too tight, the wheel bearings wear out faster.

Why replacement is needed
- Age and wear: rubber hardens, cracks, ribs separate, small chunks go missing.
- Contamination: oil or coolant softens/degrades the rubber.
- Stretching and loss of elasticity leads to slipping.
- Noise or visible damage, or if the belt breaks — engine will overheat (fan/water pump off) and electrical charging will stop (generator/alternator off).

Common failure symptoms
- Squealing on startup or under load (slip).
- Overheating (fan/water pump not effectively driven).
- Battery not charging (generator/alternator not driven).
- Visible cracks, glazing (shiny hard surface), frayed edges, or missing rib(s).
- Belt jumps off pulleys (misalignment or wrong routing).

What can go wrong if you replace incorrectly
- Wrong belt length or type → poor fit, noise, or rapid wear.
- Incorrect routing → loss of function, interference, quick failure.
- Insufficient or excessive tension → slipping or premature bearing failure.
- Damaged or seized pulley/bearing left in place → new belt fails quickly.
- Loose bolts → components shift and belt comes off; safety hazard.

Tools and parts you’ll need
- Replacement belt(s) — correct type and size for your setup. Check parts manual or measure old belt (wrap with tape and measure length), count ribs if serpentine.
- Basic hand tools: wrenches and sockets (common sizes for MF135: 9/16", 1/2", 3/4" or metric equivalents — have a set).
- Screwdrivers, pliers.
- Pry bar or long screwdriver (to lever alternator/generator for tension on manual systems).
- Torque wrench (recommended where torque values are specified).
- Straightedge or long level to check pulley alignment.
- Belt tension gauge (optional) or a ruler and a scale for deflection method.
- Cleaning rags, solvent for degreasing pulleys.
- Replacement idler/tensioner or bearings if pulleys are noisy or rough.

Preparation: identify your belt type on the tractor
- Inspect: older original MF135s use one or more V-belts. If you have a single modern multi-rib belt installed, treat it as a serpentine. The way you tension is similar: pivoting generator/alternator or adjustable idler provides tension. Replace with the same style used currently unless converting intentionally.

Step-by-step replacement (beginner-friendly)
1. Safety and prep
- Park on level ground, chock wheels, engage parking brake.
- Disconnect battery negative terminal.
- Let engine cool.

2. Expose the belt and routing
- Remove grill or fan shroud if needed for access (usually a handful of bolts).
- Sketch or take a photo of belt routing before removal — if you remove the belt, you need to put it back the same way.

3. Inspect pulleys and components
- Rotate each pulley by hand. They should spin smoothly with no roughness or play. If you feel grinding, replace that pulley or bearing.
- Check pulley grooves for glazing, nicks, or oil. Clean them with solvent and rag. Oil-contaminated pulleys must be cleaned and oil source fixed.
- Check that bolts and mounts are not loose or cracked.

4. Release belt tension
- On pivoting generator/alternator: loosen the pivot bolt (don’t remove it), then loosen the adjusting/lock nut and turn the adjustment bolt to move the generator/alternator inward to release tension.
- On systems with an idler/tensioner: loosen the tensioner lock bolt and rotate the tensioner to relieve tension.
- If a fan nut must be removed to access the belt, do so only when engine is cool and you have a proper wrench. Usually you don’t remove the fan unless necessary.

5. Remove old belt
- Slide the belt off pulleys, noting routing. If it’s a V-belt, it will seat into the pulley V groove. For multi-rib belts, ensure ribs align with groove pattern.

6. Compare belts
- Lay old and new belts together to verify length and rib count. New belt should match old one in profile and length.

7. Install new belt
- Route the new belt on all pulleys except the one used for applying tension (usually the alternator/generator or idler). Make sure the ribs sit correctly in the grooves and the belt seats fully.
- Use a bit of leverage (pry bar) on the pivoting unit if needed to fit the belt, but avoid forcing the belt over pulleys in a way that bends or twists it.

8. Apply proper tension
- Manual method (common for MF135): move the alternator/generator out using adjustment bolt until belt has the correct deflection.
- Deflection rule of thumb: at the longest span, with moderate thumb pressure (about 10 lbs / 45 N), belt should deflect about 1/4"–1/2" (6–12 mm) for multi-rib belts; for older V-belts ~1/2" (12 mm) per foot of span. If you have a belt tension gauge, follow the manufacturer’s spec. If unsure, aim for a bit firmer rather than too loose — but not rock hard.
- Tighten pivot and lock bolts while maintaining tension. Ensure you torque bolts to a firm snugness; consult manual for exact torque values — if you don’t have them, tighten solidly but don’t over-torque to avoid damaging threads.

9. Alignment check
- Use a long straightedge across pulley faces — they should be coplanar (in the same plane). Misalignment causes rapid wear or belt throw-off. Adjust mounting if needed.

10. Final checks
- Spin pulleys by hand again to check for binding.
- Reconnect battery negative.
- Start the engine and observe belt behavior at idle. Listen for squeal and watch for wobble or misrouting.
- Shut off engine and re-tighten pivot bolts if anything moved.
- Reinstall shrouds/grill.

Measurement note: if you’re uncertain about the “feel” method, many belt suppliers and repair manuals give specific deflection specs or a recommended tension test force. Using a simple spring scale can quantify your thumb pressure.

When to replace other parts at the same time
- If pulleys show wear, bearings are noisy, or the tensioner is weak, replace them while you have access. A new belt on worn pulleys will wear quickly.

Troubleshooting after fitting
- Squealing: too loose or glazed belt or contaminated pulleys. Readjust tension, clean pulleys, replace belt if glazed.
- Belt tracking off pulleys: misalignment or incorrect belt size. Fix alignment or use correct belt.
- Overheating persists: check that the fan actually spins when running and the water pump impeller isn’t failing.
- Charging issues persist: check alternator/generator and wiring after belt verified.

Quick inspection checklist after a few hours/days of operation
- Recheck belt tension — belts can seat and relax slightly. Retension if needed.
- Inspect for oil or coolant leaks onto belt. Fix leaks promptly.

Parts selection tips
- Use OEM or quality aftermarket belts designed for the tractor. Check parts books or belt diagrams for MF135 or measure the old belt.
- If converting from multiple V-belts to a single serpentine, plan carefully and confirm alignment and pulley profiles (not always a straightforward swap).

Final practical tips
- Keep the old belt until you’re sure the new one runs properly — it’s useful for length/profile reference.
- Don’t use “belt dressing” as a long-term solution — it masks problems.
- If you aren’t confident about detecting bearing noise or pulley wear, change the idler and tensioner when replacing a very old belt — cheap insurance.

That’s the full beginner mechanic’s walkthrough — components, theory, failure modes, and a stepwise replacement method. Follow safety, confirm belt type and length before buying, and inspect pulleys and bearings while you’re in there.
rteeqp73