Thwaites 6T (6 Tonne) Dumper

The Thwaites 6 Tonne Dumper is a robust and essential machine for heavy-duty construction and material handling tasks. While it is designed for durability and high performance, regular use can lead to common mechanical, hydraulic, and electrical issues.

This knowledge base offers concise solutions to the most frequent problems encountered with the Thwaites 6T Dumper. From engine and hydraulic failures to tyre wear and electrical faults, this guide provides practical steps for troubleshooting and maintenance to minimize downtime and keep your machine in peak condition.


1. Engine Starting Issues

Problem:

  • Engine fails to start or struggles to crank.
  • Causes include weak battery, faulty starter motor, or fuel delivery problems.

Solutions:

  • Battery: Check voltage, clean terminals, and ensure connections are secure. Replace if necessary.
  • Starter Motor: Test the starter motor and solenoid; replace faulty components.
  • Fuel System: Inspect fuel filters, fuel lines, and injectors for blockages. Replace clogged filters.
  • Cold Weather: Check glow plugs (diesel) and pre-heating systems.

2. Hydraulic System Failure

Problem:

  • Slow or unresponsive tipping mechanism or steering.
  • Hydraulic oil leaks or contaminated fluid.

Solutions:

  • Oil Levels: Check and top up hydraulic oil with the correct grade.
  • Leaks: Inspect hoses, seals, and connections for damage; replace worn parts.
  • Filters: Replace clogged hydraulic filters.
  • Pump: Test the hydraulic pump for performance; repair or replace if required.

3. Transmission Problems

Problem:

  • Gears slipping, difficulty shifting, or loss of power.
  • Low or contaminated transmission fluid, or worn clutch (manual systems).

Solutions:

  • Fluid: Check transmission oil levels and quality; replace if low or dirty.
  • Clutch (Manual): Inspect for wear and adjust or replace as needed.
  • Automatic Systems: Ensure gear linkages and solenoids are functioning correctly.

4. Brake System Failure

Problem:

  • Brakes feel weak, spongy, or unresponsive.
  • Hydraulic leaks, air in the system, or worn brake components.

Solutions:

  • Brake Fluid: Check fluid levels and refill using recommended brake fluid.
  • Leaks: Inspect lines, cylinders, and seals; replace damaged parts.
  • Bleeding: Bleed the braking system to remove air.
  • Pads/Discs: Replace worn brake pads, discs, or drums.

5. Overheating Engine

Problem:

  • Engine temperature rises excessively during operation.
  • Common causes include coolant leaks, blocked radiators, or faulty thermostats.

Solutions:

  • Coolant: Check levels and refill using the correct coolant mixture.
  • Radiator: Inspect for blockages or debris; clean or repair as needed.
  • Thermostat/Water Pump: Test and replace faulty components.
  • Fan Belts: Ensure belts are tight and in good condition.

6. Electrical Issues

Problem:

  • Dashboard lights, indicators, or warning systems fail.
  • Battery drains quickly, or fuses blow repeatedly.

Solutions:

  • Fuses: Check and replace blown fuses with the correct rating.
  • Wiring: Inspect for loose, corroded, or damaged wires; repair or replace where needed.
  • Alternator: Test the alternator to ensure it’s charging the battery.
  • Battery: Replace old or faulty batteries.

7. Excessive Tyre Wear or Punctures

Problem:

  • Uneven tyre wear or frequent punctures on rough terrain.

Solutions:

  • Pressure: Maintain correct tyre pressures to avoid uneven wear.
  • Load Limits: Avoid overloading beyond capacity.
  • Inspection: Check tyres for cuts, cracks, or embedded debris; repair or replace as needed.

8. Excessive Noise or Vibrations

Problem:

  • Loud knocking, rattling, or excessive vibrations during operation.
  • Worn bushings, loose components, or damaged engine mounts.

Solutions:

  • Mounts: Inspect engine and transmission mounts; tighten or replace if worn.
  • Bushings/Bolts: Check for loose or damaged bushings and bolts.
  • Drive Shaft: Inspect for wear or imbalance.

9. Exhaust Smoke Issues

Problem:

  • Black Smoke: Excess fuel burning (fuel system issue).
  • Blue Smoke: Oil burning (worn engine components).
  • White Smoke: Coolant burning (possible head gasket failure).

Solutions:

  • Black Smoke: Clean or replace air filters and check injectors for faults.
  • Blue Smoke: Inspect piston rings, valve seals, and turbocharger for oil leaks.
  • White Smoke: Check for coolant leaks, inspect head gasket, and radiator.

10. Body and Frame Wear

Problem:

  • Corrosion, cracks, or damage to the skip or chassis due to heavy loads and weather.

Solutions:

  • Rust: Regularly clean and treat corroded areas with rust protection.
  • Structural Repairs: Weld or repair cracks and reinforce weakened areas.
  • Maintenance: Regularly grease moving parts and monitor wear.

General Maintenance Tips:

  • Perform daily checks on oil levels, tyres, and visible leaks.
  • Follow the manufacturer’s service schedule for oil changes, filter replacements, and inspections.
  • Keep the machine clean to prevent build-up of dirt and debris.

By addressing these common issues and following proper maintenance practices, you can ensure your Thwaites 6T Dumper operates efficiently, safely, and reliably. If you still need help you can contact a experienced professional – That’s Us!

Spares & parts bibliography

For all spares and parts we recommend our sister company – HTS Spares

Main Parts Page: Thwaites Dumper Spares | HTS specialise in supplying dumper parts and spares for a variety of Thwaites dumpers

The guys at HTS Plant Sales are great. They obviously have a wealth of experience in compact equipment which makes dealing with them very easy.
Construction Company, Leeds