Engine loses power under load: causes and fixes

Power loss shows up most under load: the excavator slows when it hits hard ground, or the loader struggles when lifting. Before assuming a major failure, know that most power-loss cases come down to simple, inexpensive parts.

Make sure it's the engine

On hydraulic machines, weakness can come from the hydraulics rather than the engine. A simple sign: if the engine note drops hard and the engine bogs down under load, it's usually the engine. If the engine runs normally but the movement itself is slow, it's usually hydraulic.

Most common causes

• A clogged air filter choking the engine.
• Clogged fuel filters reducing fuel delivery.
• A leak in the turbo or intercooler hoses.
• A weak turbo.
• Engine overheating: some engines derate automatically to protect themselves.
• A faulty sensor or wiring that makes the engine ECU reduce power (usually with a fault code).

Checks

1. Check the machine display: any fault codes or temperature warnings? Write them down first.
2. Check the air filter and that its housing is clean.
3. Check when the fuel filters were last changed. If overdue, replace them.
4. Inspect the turbo hoses and clamps for oil or cracks.
5. Check that the radiator and intercooler are clean of dust.
6. If everything is fine, a diagnostic scan by a technician is the next step.

Summary

Start with filters and hoses before the turbo and injectors. Most power-loss cases are solved with simple service parts.