Turbochargers can spin up to 300,000 rpm and work at temperatures of 950C. Bearings inside the turbocharger work under great stress and shaft spins inside the bearing on thin film of oil. Oil seals, similar in principle to piston rings, keep the oil in place for the turbine and compressor ends of the bearing housing.
It needs positive air pressure inside the compressor and turbine to keep oil lubricating the bearings and prevent it leaking into the end housings. Any restriction on the inlet side will cause a vacuum that will draw oil beyond the seals at the compressor end housing.
If the engine idles for long periods, the turbocharger will rotate at much lower speed which in turn results in correspondingly low air pressure. The resulting vacuum will cause oil to leak into the turbine housing. Both these situations result in oil starvation to the bearings.
Oil leaks at the turbine end
¬ Leaks in the exhaust system.
¬ Leaks in the EGR system.
Oil leaks at the compressor end
¬ Blocked or restricted air intake filter.
¬ Blocked or restricted air intake pipe/hose.
¬ Air leaks on intake hoses or at the intercooler.
Oil leaks at both the compressor and turbine end
¬ Restriction in the oil drain pipe from the turbocharger to the engine or in the engine breather.
¬ Physical damage to the turbocharger’s rotating parts, and excessive bearing clearance.
¬ Repeated hot engine shutdowns producing build-up of carbon deposits in the centre housing.
Prevention of turbocharger failure from oil leakage
¬ Ensure there are no blockages or restrictions in the air and/or oil drain systems.
¬ Ensure there are no leaks in the exhaust system.