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The engine

What is the STC Red Top engine? The 4D56 rebuild explained

By Staffordshire Truck Company · Updated

A finished STC Red Top 4D56 engine with its red rocker cover on the bench
In short

The STC Red Top is Staffordshire Truck Company’s rebuilt Mitsubishi 4D56 2.5 turbo-diesel, the engine fitted to every L200 K74 it builds. The rebuild runs to 25 line items, from crack testing the block to new timing gear. Spec 2 adds a larger turbo and the STC FUELSAVE remap for 161 bhp and 30 mpg. The name comes from the rocker cover, finished in heat-proof red.

What the Red Top is

Every Mitsubishi L200 K74 we build leaves with the same engine: a 4D56 that has been taken out, stripped to the last component, tested, machined and rebuilt on our own bench in Staffordshire. We call it the Red Top because the rocker cover goes back on in heat-proof red paint, which makes one easy to spot in an engine bay.

It is not a reconditioned exchange unit and it is not an off-the-shelf remap. It is the engine that was in the truck, or a sound donor, rebuilt to a written schedule.

The 25-item schedule of works

This is the workshop’s own list, exactly as it is written up for each engine:

  1. Full engine rebuild 4D56 K74
  2. Remove engine
  3. Full strip down
  4. Crack test block
  5. Heat machine wash all parts
  6. Repaint block
  7. Paint rocker cover heat proof paint
  8. Check and replace core plugs in block
  9. Pressure test head
  10. Re seat valves
  11. Rebuild cylinder head
  12. Hone bores
  13. New piston rings
  14. New main bearings
  15. New bottom pulley
  16. New thurst washers
  17. Full gasket replacement
  18. New glow plugs
  19. New heavy duty clutch
  20. New timing gear
  21. Set up wastegate actuator
  22. New fuel filter
  23. New auxiliary belts
  24. 7 liters 15/40 mineral oil
  25. Re fit engine
A Mitsubishi 4D56 cylinder head on the bench with the valves exposed
The head off and on the bench. It is pressure tested, the valves are re-seated and it is rebuilt before it goes anywhere near the block.

Spec 1 and Spec 2: what the difference is

Spec 1 is the rebuild above on the standard turbo. Spec 2 is the same rebuild with a larger turbo, with bigger compressor and exhaust wheels, the wastegate actuator set up to suit, and our own FUELSAVE remap. The result is 161 bhp and 30 mpg, and Spec 2 is what every STC edition is fitted with as standard.

The point of the remap is in the name. The larger turbo is there for economy and drivability as much as for output; a K74 on the Spec 2 engine pulls cleanly and returns 30 mpg, which the original never managed.

Having a Red Top fitted to your own L200

The Red Top programme is available on its own if your truck is otherwise sound. One of our customers, Rob, was about to scrap a 16-year-old L200 after the engine went; it left with a new engine, fresh paint and a set of modifications, and his review is on our testimonials page in his own words.

Ring the workshop with the truck’s details and what it is doing, and we will tell you straight whether it is an engine job or something more.

An STC Red Top engine fitted in the engine bay of a Mitsubishi L200 K74
Back in the truck. New auxiliary belts, a new fuel filter, seven litres of 15/40 and it runs.

Questions people ask

All questions →
What is the STC Red Top engine?
The STC Red Top is Staffordshire Truck Company’s rebuilt Mitsubishi 4D56 2.5 litre turbo-diesel, fitted to every L200 K74 it builds. The engine is removed, stripped, crack and pressure tested, machined and rebuilt to a 25-item schedule. The name comes from the rocker cover, which is finished in heat-proof red paint.
How much power does the STC Red Top Spec 2 make?
The STC Red Top Spec 2 produces 161 bhp and returns 30 mpg in a Mitsubishi L200 K74. Spec 2 adds a larger turbo with bigger compressor and exhaust wheels, a wastegate actuator set up to suit, and the STC FUELSAVE remap to the standard Red Top rebuild.
Can I have an STC Red Top engine fitted to my own L200?
Yes. Staffordshire Truck Company offers the Red Top rebuild on its own for a Mitsubishi L200 K74 that is otherwise sound. The engine comes out, is rebuilt to the 25-item schedule and goes back in. Ring 07957 210002 with the truck’s details to get it quoted.
What oil does the STC Red Top 4D56 use?
The STC Red Top 4D56 is filled with seven litres of 15W/40 mineral oil when it is refitted, along with a new fuel filter and new auxiliary belts. That is line 24 of the workshop’s 25-item schedule.

More guides

All guides →
Buying a K74 Mitsubishi L200 K74 Buyer’s Guide: Rust, Engine, Prices Owning a K74 Mitsubishi L200 K74 Common Problems: What Goes Wrong Refurb my truck L200 Refurbishment: What A Full Rebuild Involves
Talk to the people who build them

Every truck on this site started with a phone call. Ring, tell us what you are after, a build, a refurb, or a truck that has gone bang, and we will tell you straight what it takes.

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