Engine lubricating oil is used to lubricate the bearings and provide some cooling for the turbocharger. The lubricating oil supplied to the turbocharger through the supply line is at engine operating pressure. A return line connected to the bottom of the turbocharger routes the lubricating oil back to the engine lubricating oil pan.
Seal rings are used on each end of the rotor assembly.
The primary function of the seals is to prevent exhaust gases and compressed air from entering the turbocharger
housing. Lubricating oil leakage from the seals is rare, but it can occur.
NOTE: Excessive crankcase pressure will not allow the oil to drain from the turbocharger. This will load the bearing housing and allow lubricating oil to leak past the compressor seals and into the engine.
If turbine seal leakage into the exhaust occurs on engines with a catalyst, check the exhaust restriction during the repair.
A restricted or damaged lubricating oil return line will cause the turbocharger housing to be pressurized causing lubricating oil to migrate past the seals.
Additionally, high intake or exhaust restrictions can cause a vacuum between the compressor and the turbocharger
housing resulting in oil leaking past the seals.
To verify lubricating oil leakage past the seals, remove the exhaust pipe and crossover tube and look for lubricating
oil in the turbine casing and the crossover tube. Locate and correct the restriction as previously discussed.
