Common Maintenance Oversights in Diesel Engine Care

Only cleaning the air filter while ignoring air intake short circuits. Some operators lose the internal rubber gasket after cleaning the air filter, or fail to add gaskets to intake pipe joints, secure hose ends with clamps, or repair cracked hoses. These issues cause air short circuits, allowing unfiltered air to enter the engine and accelerating wear on compression components.

Only adjusting valve clearance while neglecting valve timing. Most operators adjust valve clearance to the specified value in the manual but ignore checking if the valve timing is correct, especially for aging engines. Camshaft wear alters its geometry, causing valves to open late and close early, leading to insufficient intake, incomplete exhaust, increased fuel consumption, and reduced power. When adjusting valve clearance for aging engines, slightly reduce the clearance to compensate for timing errors. For single-cylinder diesel engines, each 0.1mm reduction in valve clearance adjusts the timing by approximately 3 degrees. However, clearance should not be less than 0.2mm to prevent valve leakage due to thermal expansion. If the clearance is 0.3mm but timing error exceeds 5 degrees, replace the camshaft.

Only checking oil sump level while ignoring oil quality. Some operators only top up engine oil without inspecting its quality, even never changing it. Old oil contains oxidized substances and metal particles, worsening lubrication and accelerating wear. Check oil quality regularly:

1.Rub old oil between fingers—discard if mechanical impurities or insufficient viscosity are felt.

2.Drop old oil on white paper—replace if the black spot is large with residue and no yellow halo.

3.Replace oil after 200 hours of operation regardless of inspection results.

Focusing on plunger/nozzle quality while neglecting delivery valve condition. Worn delivery valves cause excessive residual pressure in high-pressure lines, injector dripping, engine knocking at high speeds, and instability at low speeds. Without a tester, a simple check involves pointing the high-pressure line upward, pumping diesel until it fills the nozzle, and quickly reversing the flywheel halfway—no drop in diesel level indicates.

Prioritizing valve/valve seat condition while ignoring valve spring quality. When valves leak, operators often replace valves and seats but rarely check spring tension. Weakened springs delay valve closure and reduce sealing pressure, causing low compression and poor engine performance. To test springs without tools: place an old and new spring in series, compress them in a vice—they are if lengths and coil gaps match. Replace the old spring if it is shorter with smaller gaps.

Cleaning the oil filter but neglecting the purification chamber. Most diesel engines have hollow connecting rod journals with oil plugs (purification chambers). Oil lubricating the rod bearings centrifuges impurities onto the chamber walls. Clean these chambers and oil passages by removing plugs every 500 hours (during overhauls).

Removing combustion chamber carbon but ignoring exhaust pipe cleaning. Many operators fail to clean exhaust pipes and mufflers, where thick carbon deposits restrict exhaust flow, reducing intake efficiency and worsening combustion/overheating.

Dingbo Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to [email protected] we will pay highly attention on your question.