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Engines & Transmissions
Generators & Pumping Sets
Our Service Commitment

Harper Detroit Diesel-Allison is committed to total customer satisfaction. Along with our Toronto Head Office facility, we maintain six Regional Branches strategically placed throughout Ontario to best supply and support our dealer network.


These central locations also allow us to provide convenient, timely access to our comprehensive parts supply and enable us to offer extraordinary service and repair capabilities to all of our customers.With our Toronto head office ISO 9002 registered, delivering "World Class" customer service is our top priority. Our Service Department is ready to meet your needs whether it's a routine tune-up to a complete engine and transmission rebuild.

Our consolidated operations span 24 acres and 210,000 square feet and are staffed with over 300 employees. Utilizing more than 100 service bays and numerous state-of-the-art service tools and test equipment. All service work done at Harper Detroit Diesel - Allison is performed by factory-trained mechanics using only genuine OEM parts, reliabilt® components, Detroit Diesel branded Powerguard filters and Power Cool cooling system products, and other OEM branded accessory components.

Services Offered:
  • Truck Shop Services
  • Complete Machine Shop Facility
  • Complete Engine & Transmission Rebuilding Capabilities
  • Diagnostic Services
  • Engine &Transmission Dynamometer
  • Chassis Dynamometer (Toronto & Oshawa Locations)
  • Front End Alignment (Oshawa Location)
  • In shop & Mobile Heavy Duty Diesel Ontario Drive Clean Testing
  • Air Improvement Program
  • 24/7 Emergency Road Service
  • On-Site Training Facility
  • On-Line Appointment Booking
  • Financial Service
24/7 Emergency Road Service

All Harper Detroit Diesel-Allison locations have a 24-hour Emergency Road Service.
We're there when you need us!

Call 1-800-6HARPER.