Team Restored 73-Year-Old Mirrlees JS8 Diesel Engine
The vintage engine was successfully brought back to life, achieving full operation on all eight cylinders.
Updated on Oct. 7, 2026 in Car Maintenance
The Mr. Hewes team has successfully restored a 73-year-old Mirrlees JS8 diesel engine to working order. The massive engine was brought back to functionality, firing on all eight cylinders during recent operations.
Why it matters
Restoring industrial machinery of this vintage preserves complex engineering history that predates modern, highly digitized power systems. This project demonstrates the feasibility of maintaining aging equipment that would otherwise be decommissioned.
The engine features a 102.8-liter displacement and generates 700 horsepower. It has a recorded history of 720 hours of operation across its 73-year lifespan.
The players
Mr. Hewes team
This is the group of mechanics and restoration experts responsible for the mechanical recovery of the antique diesel engine.
The details
To restore the engine, the team manually primed the oil system while addressing mechanical issues including stuck valves, cam followers, and injector pumps. After discovering water in the sump, they bled the individual injector pumps to ensure consistent firing across the cylinder block.
Timeline
October 7, 2026: The restoration story was published.
Roadmap
This restoration highlights a niche but critical sector of the automotive and industrial world focused on the preservation of mechanical heritage. It positions such projects against the global industry trend of rapid, mass-market electrification and the planned obsolescence of internal combustion systems.
For enthusiasts and industrial historians, this restoration proves that high-displacement vintage machinery remains serviceable with diligent manual maintenance. Daily drivers and buyers should note that this underscores the durability of long-stroke diesel designs compared to modern engines.
The takeaway
Restoring aging machinery requires meticulous attention to basic mechanical systems like valves and injector pumps to overcome decades of neglect. Collectors can apply these same priming and cleaning techniques to salvage other vintage engines currently sitting dormant.
Further reading
For more on mechanical preservation, visit the Car Maintenance section.
Source note: This article includes information reported by SlashGear.
