What are the symptoms of a faulty engine oil-gas separator?
4 Answers
Introduction to symptoms of a faulty engine oil-gas separator: Vehicle vibration: When the oil-gas separator malfunctions, the engine will exhibit noticeable vibrations accompanied by whistling-like noises. Warning light activation: Check if the vehicle's dashboard displays any warning lights. Illuminated warning lights often indicate excessively rich air-fuel mixture caused by oil-gas separator failure. Air leakage from separator holes: Most oil-gas separator failures result from damaged diaphragms. During idle operation, try covering the separator's holes with your finger. If air leakage is detected, this confirms separator damage.
Just looked into this a couple days ago when my friend's car had issues. If the engine's oil-gas separator fails, the most obvious symptoms are suddenly burning oil like crazy, needing to top up oil every few days, and blue smoke puffing from the exhaust like it's burning oil. The engine might shake like a tractor at idle, and RPMs fluctuate wildly when you step on the gas. Pop the hood and you'll see black oily sludge around the intake manifold and throttle body, with worsened carbon buildup on valves and piston tops. If left untreated, the catalytic converter will eventually clog up. Next service, remind your mechanic to check for oil seepage around the crankcase vent tube – that's the easiest telltale sign.
Last time when my car was being repaired, the mechanic specifically explained the principle to me. The oil-gas separator is responsible for filtering and recirculating the oil vapor. Once it fails, this oil-laden mixture will directly rush into the combustion chamber. The result is that the spark plugs get fouled with oil residue, causing ignition difficulties, and you'll feel particularly strenuous when starting a cold engine. The exhaust will have a noticeable abnormal odor, and fuel consumption will increase by about 10-20%. Some cars may even trigger the engine warning light on the dashboard during sudden acceleration. In the early stages of such problems, you might not feel obvious vibrations, but a sudden increase in oil consumption is a crucial signal. Pay special attention to changes in the oil dipstick level.
Fix it immediately when it's broken. I've seen several cases where people delayed repairs, and it ended up requiring major engine overhauls. Oil vapor leaking into the intake system can coat the entire inner walls of the intake tract with an oil film, disrupting the air-fuel ratio and causing abnormal combustion. The ECU is forced to repeatedly adjust ignition timing, leading to unstable power output. If sludge jams the crankcase ventilation valve, excessive pressure on the seals can cause oil leaks. The worst scenario is when these contaminants enter the turbocharger—oil sludge sticking to the high-speed turbine blades can render them useless. It's recommended to have a technician inspect the intake pipes every 50,000–60,000 km. Early detection can save you a fortune.
