The oil filter is clogged and the bypass valve is
A lubrication valve or filter bypass valve
malfunctions as a result of worn or binding
If enough contaminated oil enters the turbocharger
bearings, the bearings will wear out or large particles
may plug the internal oil passages and starve the
turbocharger of oil.
Because of the extremely high top speeds of the
turbine and compressor wheels (up to 100 mph), any
large particles that enter through the inlet or exhaust
systems can mechanical y damage the rotating parts of
the turbocharger. Therefore, proper maintenance of the
air cleaner is extremely important. Also, thorough
cleaning of the inlet and exhaust systems is essential if
there has been a previous turbocharger failure, valve
failure, or other failure that could leave foreign particles
in the engine.
Removal, Disassembly, and Cleaning
The removal of the turbocharger from the engine is
not a complicated task when you follow the procedures
in the manufacturers instructions.
After removing the turbocharger from the engine,
you should make sure the exterior of the turbocharger is
cleaned of all loose dirt before disassembly to prevent
unneccessary scoring of the rotor shaft. Disassemble it
according to the manufacturers maintenance and repair
The turbocharger parts accumulate hard-glazed
carbon deposits, which are difficult to remove with
ordinary solvents. This is especially true if the turbine
wheel and shaft, diffuser plate, and the nozzle ring and
inner heat shield are affected. The cleaner must remove
these stubborn deposits without attacking the metal. All
parts should be cleaned as follows:
1. Place all parts in a divided wire basket so parts
will not be damaged through contact with each other. Do
not pile them in the basket. Avoid mutilating precision
2. Immerse the parts in mineral spirits or similar
Never use a caustic solution or any type
solvent that may attack aluminum or nonferrous
3. Allow the parts to soak as needed to remove the
carbon. A soft bristle brush maybe used, if necessary, to
remove heavy deposits. Never use wire or other brushes
with stiff bristles.
4. With the oil orifice removed, flush out the oil
passages in the main casing from the bearing end to
remove dirt loosened by the soaking.
5. Remove the parts from the tank. Drain and steam
clean thoroughly to remove all carbon and grease. Apply
steam liberally to the oil passages in the main casing.
6. Blow off excess water and dry all parts with
filtered compressed air.
7. Carefully place parts in a clean basket to avoid
damaging them before inspection and reassembly.
Inspect all turbocharger parts carefully before you
rinse them. All parts within manufacturers
recommended specifications can be used safely for
another service period. Damage to the floating bearing
may require replacement of the turbocharger main
casing with a new part or an exchange main casing.
Inspect the turbine casing. If you find cracks which
are too wide for welding, replace the casing.
Do not use the exhaust casing if it is warped or
heavily damaged on the inside surface caused by contact
with the turbine wheel or a foreign object, or if it is
cracked in any way.
Usually, oil seal plates do not wear excessively
during service and can be reused if they have not been
scored by a seizure of the piston ring.
As you inspect the diffuser plates, look for contact
scoring by the rotor assembly on the back of the diffuser
plate or broken vanes. This scoring will make the plate
unacceptable for reuse.
Inspect the inner heat shield. If it is distorted, replace
Dents found on the outer heat shield can usually be
removed, allowing its reuse. However, if this shield is
cut or split in the bolt circle area, replace it.