Mitsubishi GS16-GS25 operation and starting
Good starting your Mitsubishi GS16-GS25 starts with the right sequence and correct preheating. This page explains step by step how to start the GS16, GS18, GS20, GS21, GS23 or GS25, how preheating works, what the instrument panel lights mean, and what to watch out for in cold weather.
Suitable for the entire series: Mitsubishi GS16, GS18, GS20, GS21, GS21S, GS23, GS25 and GS25S.
Starting the Mitsubishi GS16-GS25 step by step
The ignition switch has the positions stop, off, on, preheat (run) and start. Always start in this order:
- Put the gears in neutral and fully depress the clutch — otherwise the engine won't start (safety switch).
- Turn the key to the preheat (run) position. The glow lamp lights up.
- Wait until the glow lamp goes out. Then turn the key further to start.
- Release the key immediately after the engine starts; it automatically springs back to the on position.
- Check that the oil pressure light and the charge light go out. If they don't go out, switch off the engine immediately and find the cause.
After starting, let the engine warm up for about 5 minutes at around 1,500 rpm before working. Warming up isn't just for winter: loading the engine cold shortens its lifespan.
Mitsubishi GS16-GS25 preheating explained
Preheating warms the combustion chambers so the diesel ignites more easily. On the GS series, this happens automatically: as long as the glow lamp is lit, the glow plugs are preheating; once the lamp goes out, the engine is ready to start. Good to know: on a warm restart or after repeated start attempts, the glow lamp lights up for a shorter time or not at all — this is a protective circuit protecting itself, not a fault.
If the engine starts poorly when cold, worn glow plugs or a weak battery are by far the most common cause with grey imports. Both are easy to check and affordable to replace. More starting problems and solutions can be found in the blog Mitsubishi GS16-GS25 troubleshooting.
Mitsubishi GS16-GS25 instrument panel and lights
On the instrument panel, you keep an eye on the most important functions. These warning lights are crucial:
| Light | Meaning | Action |
|---|---|---|
| Glow lamp | Preheating active | Wait until off, then start |
| Oil pressure light | Insufficient oil pressure | Must go out after starting; stays lit → switch off immediately |
| Charge light | Alternator not charging | Must go out after starting; stays lit → check belt/alternator |
Mitsubishi GS16-GS25 driving off and shifting
Before driving off: set the engine to around 1,500 rpm, fully depress the clutch and select the desired gear using the main, range and shuttle lever. The transmission has 8 forward and 8 reverse gears. If shifting feels stiff, don't force it — depress the clutch again and try again. Then firmly press the brake pedal, release the parking brake, and let the clutch out smoothly to drive off.
Mitsubishi GS16-GS25 cold starting
At low temperatures, use engine oil and diesel suited to the cold. According to the manual: SAE 10W-30 across the wide temperature range, and for fuel, standard diesel down to about -10 °C, winter diesel down to about -20 °C, and special winter diesel below that. A fully charged, healthy battery and good glow plugs make the difference between starting and not starting in winter.
Product tip. Poor cold starting? Start with the glow plugs (SKU-55808) — the cheapest and most common culprit. If the starter motor isn't turning over properly at all anymore, the starter motor 12 V / 1.6 kW (SKU-1290016) is the direct replacement for the S3L/S3L2.
