Ford 655C Fan Belt Replacement

[MikePhua]

Why This Job Matters
On a Ford 655C backhoe loader, the fan belt drives the alternator and water pump, and in some builds the hydraulic charge or air-conditioning compressor. A slipping or broken belt can cascade into low voltage, rising coolant temperatures, and unexpected shutdowns. Replacing it is a fast, high-value maintenance task that restores charging and cooling performance and prevents collateral failures like battery sulphation and head-gasket stress from repeated overheating cycles.
A Quick Word on the Machine
The Ford 655C is a late-1980s to early-1990s generation 4×4 backhoe loader that bridged the blue-oval era into New Holland’s ownership. Typical builds used a naturally aspirated, mid-displacement Ford BSD diesel with mechanical injection, open-center hydraulics, and simple belt drive for accessories. Globally, backhoe loaders of this size class have ranked among the top construction machines by unit sales for decades because they combine loader productivity with excavator reach in one road-legal package. That popularity means parts like belts, idlers, and pulleys remain widely cross-referenced across aftermarket catalogs.
Symptoms That Point To Belt Service

• Intermittent battery warning lamp at idle that disappears with revs
  
• Chirping or squealing on cold start, especially in damp weather
  
• Visible glazing, fraying, or cracking of belt ribs/sidewalls
  
• Coolant temps trending higher under load despite a clean radiator
  
• Black dust accumulation near the alternator or front timing cover
  

Terminology Cheat Sheet

• V-belt: A trapezoid-section belt riding in pulley grooves; common on older 655C builds.
  
• Serpentine belt: A multi-rib flat belt; some units with factory A/C or later updates may use this.
  
• Idler pulley: A free-wheeling pulley that guides the belt’s path.
  
• Tensioner: Either a spring-loaded arm or a manual adjustment (alternator swing bracket on the 655C).
  
• Deflection method: Measuring how far a belt moves at mid-span under a set force to judge tension.
  
• Frequency method: Measuring belt tension by its vibration frequency (belt like a “guitar string”).
  

Preparation and Safety

• Park on level ground, lower buckets, set the parking brake, key off, and disconnect the negative battery cable.
  
• Allow the engine and radiator to cool completely.
  
• Have a straightedge, belt routing sketch or photo, 3⁄8" and 1⁄2" drive metric sockets/spanners, a torque wrench, and a small pry bar.
  
• Typical fasteners on the alternator pivot and slider are metric (commonly M10). Expect tight spaces—remove the fan shroud top half if needed for access.
  

Identify Your Belt and Routing

• Count grooves if it’s ribbed; measure outer circumference with a tailor’s tape or string.
  
• Note each accessory in the loop: crank pulley, water pump, alternator, and possibly A/C compressor.
  
• If your machine uses dual belts (common on heavy-duty alternator/water pump drives), replace them as a matched set.
  

Removal Steps

1. Unload the belt
   • Loosen, do not remove, the alternator pivot bolt at the engine bracket.
     
   • Loosen the alternator slider/lock bolt on the slotted bracket.
     
   • Swing the alternator inward to relax belt tension.
     
2. Slip the belt off the smallest, smoothest pulley last
   • Usually that’s the alternator. If dual belts are fitted, walk each off evenly to avoid binding.
     
3. Spin all pulleys by hand
   • Alternator should turn smoothly with light cogging from the brushes (not gravelly).
     
   • Water-pump should be silent with zero wobble. Any grit, play, or leakage track = plan a pulley or pump service.
     

Inspection You Shouldn’t Skip

• Pulley grooves: Clean rust and rubber glaze; misaligned or nicked grooves shred new belts.
  
• Alignment: Lay a straightedge across the crank and alternator pulley faces; faces should be in plane.
  
• Electrical load: Big auxiliary loads (work lights, hydraulic fan conversions) increase belt slip risk—ensure pulley wrap on the alternator is adequate.
  

Installation and Tensioning

• Route the new belt per your photo/sketch, seating it fully in each groove.
  
• Pull the alternator outward to tension. Use the pry bar on the alternator body only where the casting is reinforced; never pry on the fan.
  
• Snug the slider/lock bolt first, then the pivot bolt after tension is set.
  

Target Tension
Use one of the two proven field methods below. Choose the one you can repeat accurately.

• Deflection method
  • Span: Measure between the two pulleys with the longest straight run.
    
  • Force: About 10 kgf (≈98 N).
    
  • Deflection:
    • New V-belt: about 10–12 mm per 300 mm of span.
      
    • Used belt re-tension: about 8–10 mm per 300 mm of span.
      
  • Example: If your longest span is ~300 mm, look for roughly a finger-width of movement with firm push.
    
• Frequency method
  • Pluck the longest span; many phone apps will read frequency.
    
  • Typical targets: 100–140 Hz for a short, single-accessory span on a mid-displacement diesel.
    
  • Consistency beats perfection—record your number for future checks.
    

Torque Values That Prevent Comebacks

• Alternator pivot bolt (M10): 40–45 N·m
  
• Alternator slider/lock bolt (M8–M10, check size): 23–40 N·m
  
• Idler bracket bolts (if fitted, M10): 35–45 N·m
  

Re-check torque after the first hour of operation; thermal cycling and belt bedding-in can relax clamp loads.
After-Start Checks

• Watch the belt at idle and 1,500 rpm—no flutter or oscillation should be visible.
  
• Listen for squeal on sudden throttle blips; a quick chirp signals under-tension.
  
• Confirm charging voltage at battery posts: typically 13.8–14.4 V with a warm engine and minimal electrical load.
  
• After the first day’s work, re-verify deflection or frequency and re-torque the slider and pivot fasteners.
  

Common Pitfalls and Fixes

• Persistent squeal on wet mornings
  • Clean pulleys with isopropyl alcohol; avoid belt dressings—they mask slippage and attract grit.
    
  • Increase wrap angle on the alternator by ensuring the belt is on the correct groove set and brackets aren’t bent.
    
• New belt shreds quickly
  • Check pulley alignment and groove wear; a hooked or razor-edged groove cuts belts.
    
  • Verify you installed the correct belt width; a narrow belt bottoms out and slips.
    
• Voltage low despite proper tension
  • Alternator bearings may be dragging or the regulator is weak. Belt changes won’t rescue a failing alternator.
    
  • Measure for voltage drop in the charge cable and grounds; high resistance loads the belt.
    

Preventive Maintenance Intervals

• Visual belt check: every 250 operating hours or monthly in seasonal fleets.
  
• Tension check: at installation, at 1–2 hours, and then every 250 hours.
  
• Pulley alignment check: every 1,000 hours or after any front-end service that disturbs brackets.
  

Anecdote From The Yard
A municipal crew running a mixed fleet noticed repeated winter-morning squeal on one 655C after installing high-draw LED plow lights. The alternator pivot bracket had a slight twist, reducing belt wrap on the alternator pulley. A 10-minute tweak with a straightedge and a shim restored the wrap angle, the squeal vanished, and the charging voltage at idle rose by about 0.3 V. The “fix” wasn’t a tighter belt—it was geometry.
Upgrades Worth Considering

• Alternator with larger pulley: Reduces belt speed and slip under high load, especially with added electrical accessories.
  
• Dual-belt conversion: If your machine runs a heavy-duty alternator or A/C in hot climates, twin matched belts share the load.
  
• Spring tensioner retrofit: On serpentine conversions, a quality spring tensioner keeps tension consistent as the belt wears.
  

Troubleshooting By Data

• A handheld IR thermometer on the alternator housing is a great proxy: a belt-slip machine will show elevated alternator case temperatures at modest electrical loads.
  
• Belt frequency logs before and after a job provide a numeric trend; if frequency drops >15% between checks, tension or bracket integrity needs attention.
  

About The Brand And Support Reality
Ford’s construction equipment heritage emphasized mechanical simplicity and field-serviceability. That design philosophy is why the 655C’s belt job remains straightforward: manual adjustment, accessible brackets, and standard hardware. As the line transitioned into New Holland’s portfolio, parts sourcing broadened rather than shrank, and consumables like belts, idlers, and alternator hardware stayed generic enough to be widely available.
Quick Reference Checklist

• Confirm routing and accessories
  
• Inspect pulleys and alignment
  
• Install correct belt width/length; replace duals as matched pairs
  
• Set tension by deflection or frequency
  
• Torque pivot and slider bolts
  
• Verify charging voltage and re-check after first shift
  

Closing Thought
A belt swap on a 655C is more than a routine chore—it’s the hinge point for cooling and charging reliability. Take five extra minutes for alignment and tension verification, and you’ll save hours of troubleshooting down the road.