BODY-SELECTOR 6I9874 - Caterpillar

Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Note: Technical Information Bulletin, TIBU6042, "Troubleshooting High Crankcase Pressure Faults on Certain C13 and C15 Truck Engines" must be performed and proved unsuccessful before applying this Technical Information Bulletin.Problem
Turbochargers are equipped with ring seals between the bearing housing and the area behind the compressor wheel. The design of the seals is for reduction of blowby. The design is not for positive contacting seals for oil leaks. The oil leak is typically a system problem that causes leaks across the turbocharger seals. Troubleshooting these leaks from a system viewpoint is important. Replacing the turbocharger is the common action. In most cases, replacing the turbocharger does not prevent the oil leak from coming back.Solution
Review the following steps for troubleshooting before you replace the turbocharger.
Check in order to make sure that all of the oil drain lines are clear of any obstructions.
Check all restrictions of the engine.
Check all inlet restrictions.
An inlet restriction can create a low-pressure area in the compressor of the turbocharger. This can draw oil from the bearing housing across the seals.
An excessively low exhaust restriction can potentially draw oil across the seal of the turbine wheel and the seal to leak into the exhaust piping.
Check in order to make sure that the Clean Gas Induction (CGI) device is functioning properly.
If the CGI device fails in a way that closes off fresh air to the turbocharger under conditions above, the CGI may cause an excessive inlet restriction to the low-pressure turbocharger that may draw oil from the bearing housing across the seals.
The CGI device may be the cause of the oil leak. Check the low-pressure turbocharger for any evidence of oil that is being taken in.
Ensure that the inlet duct is not collapsing.
If the inlet duct to the CGI device collapses this may cause an excessive inlet restriction to the low-pressure turbocharger that may draw oil from the bearing housing across the seals.
The duct should have a metal spring that will reinforce the structure in order to prevent collapsing.
Check the system for any boost leaks.
Any boost leak can cause oil to be drawn across the seals.
Check for exhaust leaks.
An exhaust leak can cause the low-pressure turbocharger to be low on boost. This may cause oil to be drawn across the seals.
Check in order to make sure that the crankcase pressure is not excessive.
If the crankcase pressure is elevated by 10.3 kPa (1.5 psi), oil can be drawn across the seals.If the above listed checks have been done and nothing has been found, replace the turbocharger.Note: It is likely that there will be a boost leak or an OCV filter plugged.