Mitsubishi K4 maintenance: oil, filters and adjustment values
Good maintenance of your Mitsubishi K4 is the difference between an engine that runs for tens of thousands of hours and a costly overhaul. In this guide, we go through the complete maintenance schedule for the four-cylinder K4: engine oil, filters, valve clearance, V-belt and injection timing — with the intervals and adjustment values as specified by Mitsubishi.
Suitable for the entire K4 series: K4A, K4B, K4C, K4D, K4E, K4F, K4G, K4M and K4N (four-cylinder diesel). The data below comes from the workshop manual for the direct-injection K4E, K4F, K4G and K4M; for an indirect-injection version, check your engine number and bore.
Mitsubishi K4 engine oil: type and change interval
Use an engine oil that meets at least API classification CC. If the engine runs under heavy load or with a turbo, choose API CD. The correct viscosity depends on the ambient temperature:
| Ambient temperature | Recommended viscosity (SAE) |
|---|---|
| Above 20 °C | SAE 30 or 10W‑30 |
| 5 to 20 °C | SAE 20 or 10W‑30 |
| Below 5 °C | SAE 10W‑30 |
Change the engine oil for the first time after 50 operating hours (the break-in service) and every 100 operating hours thereafter. Replace the oil filter every 200 operating hours. Top up to the upper mark on the dipstick; take into account the capacity of your version:
| Model | Oil capacity (max / min) |
|---|---|
| K4E / K4F | 4.5 L / 3.0 L |
| K4M | 5.0 L / 3.0 L |
The oil filter and oil gallery together hold about 0.5 liters — factor this in when replacing the filter. Tighten the drain plug to 5–6 kgf·m (49–59 Nm) and the new oil filter by hand to 1.1–1.3 kgf·m; lightly lubricate the O-ring with clean oil and make sure it doesn't shift. Mitsubishi strongly advises using an original or equivalent oil filter — not a filter meant for a different engine model.
Replacing Mitsubishi K4 filters
The K4 has three filters that require maintenance: the engine oil filter, the fuel filter and the air filter. A clogged fuel or air filter directly costs power and increases consumption; an old oil filter lets dirt through to the bearings. Replace them together during the major service. After replacing the fuel filter, bleed the fuel system (filter, pump and injector lines) so the engine starts smoothly again.
Maintenance parts for the Mitsubishi K4
- Filter set Iseki TU/TX – K series (SKU-10040) — oil, fuel and air filter plus copper drain ring, for K4-powered Iseki TU/TX and Bolens.
- Engine oil filter Mitsubishi (SKU-018) — M20×1.5 thread; check the size against your machine.
- V-belt Iseki/Mitsubishi K series (SKU-124006) — the fan belt for cooling and alternator.
Not sure which filter fits your machine? Send us the type or the engine number, and we'll figure it out.
Adjusting valve clearance on the Mitsubishi K4
Check the valve clearance with a cold engine and adjust it after retightening the head bolts. The clearance is 0.25 mm for both the intake and exhaust valve. Set the relevant cylinder to top dead center of the compression stroke, measure with a feeler gauge, and correct by loosening the adjusting nut on the rocker arm and adjusting the set screw. Hold the set screw in place while retightening the lock nut. Too tight a valve clearance will eventually lead to burnt valves; too much clearance causes a ticking noise and loss of power.
Tensioning the V-belt (fan belt)
A properly tensioned V-belt ensures the water pump and alternator run at sufficient speed. Press the belt midway between the alternator and crankshaft pulley: the deflection should be 10 to 12 mm with a pressing force of about 10 kg. Retension by shifting the alternator. A slipping belt causes overheating and a draining battery, so check it for tension and cracks at every service.
Checking injection timing
The injection timing is set at 19° before top dead center (agricultural version) or 20° (industrial and export). Adjustment is done using the thickness of the shim under the injection pump: a thicker shim retards the timing, a thinner one advances it. Incorrect timing causes starting problems, black smoke or loss of power — reason enough to have this checked if in doubt.
Maintenance schedule at a glance
| Interval | Action |
|---|---|
| Daily | Check oil level, coolant, air filter and for leaks |
| First 50 hours | Change engine oil (break-in service), check head bolts and valve clearance |
| Every 100 hours | Change engine oil, check V-belt tension |
| Every 200 hours | Replace oil filter, fuel filter and air filter |
| Periodically | Check valve clearance (0.25 mm) and injection timing |
Frequently asked questions
How much oil goes into a Mitsubishi K4?
About 4.5 liters for the K4E and K4F and 5.0 liters for the K4M (up to the upper mark on the dipstick). Allow about 0.5 liters extra for a filter change.
What oil does a K4 need?
A diesel oil of at least API CC (CD under heavy load), with a viscosity suited to your climate — SAE 30 or 10W‑30 above 20 °C, 10W‑30 in cold conditions.
How often should I change the oil?
The first time after 50 hours, then every 100 hours. The oil filter every 200 hours.
