How to Determine if an Oil Pump Engine Has Cylinder Scoring?
4 Answers
When diesel engine cylinder scoring occurs, the vehicle will experience jerking sensations, accompanied by significant abnormal noises from the engine. The RPM will also decrease, and there will be a noticeable drop in power. Here are the methods for cleaning the oil cylinder: Draining the Cylinder Fluid: Extract the hydraulic oil from the oil cylinder, trying to leave as little as possible at the bottom. Cleaning the Dirt: Open the oil cylinder cover and remove the oil sludge from the bottom. After cleaning thoroughly, use diesel to wash the oil cylinder and filter screen again. Once completed, drain all the waste oil and wipe the oil cylinder clean with a clean cloth. Filtering: After completing the above steps, wait for a while before pumping the hydraulic oil back in or filtering it through cotton gauze.
Last time I helped a friend deal with a similar issue. When an oil pumping unit experiences cylinder scoring, there will be obvious metal friction sounds, especially at low speeds—it sounds like sandpaper grinding. The oil pressure gauge needle will suddenly drop, while the temperature gauge shoots up. The most noticeable symptom is the sluggish power output; the pumping rod moves weakly. At this point, you must shut down the machine immediately—otherwise, by the time you see blue smoke from the exhaust pipe, it's already too late, as it usually means the piston rings and cylinder walls have already been deeply scored. I remember last time when we opened it up, the cylinder walls were scraped with shiny metal streaks. Such issues can’t be delayed—if you notice anything unusual, call the maintenance team right away, or the entire crankcase could be ruined.
We who do equipment inspections dread encountering cylinder scoring the most. When taking readings in the morning, be extra vigilant: a sudden increase in oil consumption by more than 30% should raise alarms. Don't just count the pumping cycles when listening for sounds—if you hear a 'grinding' noise, especially during the transition between up and down strokes, it's likely the cylinder walls are scratched. There's also a practical method: feel the side of the crankcase with your hand. If it's too hot to keep your hand on, combined with reduced oil output, you can pretty much confirm it. Just last week, we encountered a nodding donkey machine that was initially detected this way. Upon disassembly, we found three half-millimeter-deep grooves in the fourth cylinder.
Old mechanics rely on three key tools for diagnosis: a stethoscope, a pressure gauge, and an oil dipstick. Place the mechanical stethoscope against the middle of the cylinder block—if there's cylinder scoring, you'll hear a screeching sound like a metal spoon scraping a pot. Measuring cylinder pressure is more precise; if the pressure difference between adjacent cylinders exceeds 15%, there's definitely an issue. Checking the oil dipstick is even more telling—if metal shavings cling to it like pencil lead dust, it means the cylinder wall metal is starting to flake off. In this case, the engine must be shut down immediately, as continued operation will damage the connecting rod bearings.
