Mitsubishi 4M40 Engine

In 1993, the second generation of the Mitsubishi Pajero received a new diesel engine, the 4M40. This engine was intended to replace the older 4D56 but ended up being produced alongside it.

The 4M40 features an in-line 4-cylinder cast iron cylinder block with two balancer shafts, designed for enhanced smoothness.

Characteristics of the 4M40 engine

Property Value
Production Kyoto engine plant
Engine Make 4M4
Years of Manufacture 1993-2006
Cylinder Block Material Cast Iron
Engine Type Diesel
Configuration In-line
Number of Cylinders 4
Valves per Cylinder 2
Piston Stroke, mm 100
Cylinder Diameter, mm 95
Compression Ratio 21.0
Engine Capacity, cc 2835
Engine Power, hp/rpm 80/4000
Torque, Nm/rpm 198/2000
Environmental Standards
Turbocharger MHI TF035HM-12T
Engine Weight, kg 260
Fuel Consumption (Pajero 2) City: 15.5 l/100 km, Highway: 10.7 l/100 km, Mixed: 12.5 l/100 km
Oil Consumption, g/1000 km Up to 1000
Engine Oil 5W-30, 5W-40, 10W-30, 15W-40
Oil Capacity, l 6.5
Recommended Oil Change, km 15,000 km (or better 7,500 km)
Engine Operating Temperature, degrees 90
Engine Life, thousand km According to the plant: —, In practice: 400+
Tuning, hp Potential: —, Without Loss of Resource: —
The Engine was Installed In Mitsubishi L200/Triton, Mitsubishi Pajero, Mitsubishi Pajero Sport/Challenger, Mitsubishi Delica

Here are key specifications of the 4M40 engine

  • Cylinder Block: It utilizes a cast iron in-line 4-cylinder block with balancer shafts to reduce vibrations.
  • Crankshaft: Inside the block is a forged crankshaft with a piston stroke of 100 mm. The piston diameter is 95 mm, and the compression height is 51.6 mm, resulting in a working volume of 2.83 liters.
  • Cylinder Head: The cylinder head is made of aluminum and features an 8-valve configuration, a single camshaft, and vortex combustion chambers. The intake valves have a diameter of 41 mm, while the exhaust valves are 35 mm in diameter. The valve stem diameter is 8 mm.
  • Valve Adjustment: Valve adjustment is necessary roughly every 15,000 kilometers. On a hot engine, the valve clearances should be set at 0.25 mm for intake valves and 0.35 mm for exhaust valves.
  • Timing Drive: The engine uses a double-row chain for the timing drive, which has an approximate lifespan of 250,000 to 300,000 kilometers.

Evolution of the 4M40 Engine

Initially, a version of the 4M40 was produced with a mechanical injection pump, equipped with an MHI TF035HM-12T turbocharger and an intercooler. This version delivered 125 horsepower at 4000 rpm and produced a torque of 294 Nm at 2000 rpm.

In May 1996, Mitsubishi began producing a version of the 4M40 engine with EFI (Electronic Fuel Injection). This EFI-equipped engine increased the power output to 140 horsepower at 4000 rpm, with torque increasing to 314 Nm at 2000 rpm.

Starting in 1999, the 4M40 engine began to be gradually replaced by the 3.2-liter 4M41 engine, and by 2006, this transition was fully completed.

4M40 engine Common Problems and Disadvantages

  1. Noise and Timing Chain Issues: There’s a high probability of the timing chain stretching, which can lead to noise and ringing. Replacing the timing chain before it breaks is advisable.
  2. Cylinder Head Cracks: Cracks in the cylinder head are a common issue. Gases in the expansion tank are indicative of this problem, and it is often better to replace the entire head.
  3. Starting and Stalling Issues: Starting problems or engine stalling can often be attributed to the fuel injection pump seal, which may need replacement. Checking the return valve is also recommended.

The turbo’s service life is approximately 300,000 kilometers. Regular cleaning of the EGR (Exhaust Gas Recirculation) valve is important to prevent carbon buildup, which can lead to smoking and decreased performance. Many owners choose to disable the EGR after the initial cleaning.

With proper maintenance, good diesel fuel, and quality oil, the 4M40 engine can prove to be reliable and have a service life exceeding 400,000 kilometers.

Tuning the 4M40 Engine

Unfortunately, there is limited availability of chip tuning or turbo kits for the 4M40 engine. This means that significant power enhancements are not easily achievable, and it may be more practical to consider upgrading to a more powerful vehicle if you require more performance.

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