Perkins 1204F-E44TA Systems Operation Testing And Adjusting page 23

UENR4490-01
When the load on the engine increases, more fuel is
injected into the cylinders. The combustion of this
additional fuel produces more exhaust gases. The
additional exhaust gases cause the turbine and the
compressor wheels of the turbocharger to turn faster.
As the compressor wheel turns faster, air is
compressed to a higher pressure and more air is
forced into the cylinders. The increased flow of air
into the cylinders allows the fuel to be burnt with
greater efficiency. This produces more power.
A wastegate is installed on the compressor side of
the turbocharger. The wastegate is a valve that
allows exhaust gas to bypass the turbine wheel of the
turbocharger. The operation of the wastegate is
dependent on the pressurized air (boost pressure)
from the turbocharger compressor. The boost
pressure acts on a diaphragm that is spring loaded in
the wastegate actuator which varies the amount of
exhaust gas that flows into the turbine.
The wastegate regulator (15) is controlled by the
engine Electronic Control Module (ECM). The ECM
uses inputs from a number of engine sensors to
determine the optimum boost pressure. This will
achieve the best exhaust emissions and fuel
consumption at any given engine operating condition.
The ECM controls the wastegate regulator, that
regulates the boost pressure to the wastegate
actuator.
When higher boost pressure is needed for the engine
performance, a signal is sent from the ECM to the
wastegate regulator. The wastegate regulator
reduces the pressure in the air inlet pipe (14) that
acts upon the diaphragm within the wastegate
actuator (13).
The spring within the wastegate actuator (13) forces
the wastegate valve that is within the turbine housing
to close via the actuating rod and lever. When the
wastegate valve is closed, more exhaust gas is able
to pass over the turbine wheel. This results in an
increase in turbocharger speed and boost pressure
generation.
When lower boost pressure is needed for the engine
performance, a signal is sent from the ECM to the
wastegate regulator. This causes high pressure in
the air inlet pipe (14) to act on the diaphragm within
the wastegate actuator (13). The actuating rod (12)
acts upon the actuating lever to open the valve in the
wastegate. When the valve in the wastegate is
opened, more exhaust gas from the engine is able to
bypass the turbine wheel. The exhaust gases bypass
the turbine wheel results in a decrease in the speed
of the turbocharger.
The shaft that connects the turbine to the compressor
wheel rotates in bearings (4) and (6). The bearings
require oil under pressure for lubrication and cooling.
The oil that flows to the lubricating oil inlet port (5)
passes through the center of the turbocharger which
retains the bearings. The oil exits the turbocharger
from the lubricating oil outlet port (10) and returns to
the oil pan.
This document has been printed from SPI2. NOT FOR RESALE
Crankcase Breather
The engine crankcase breather is a filtered system.
The crankcase breather system consists of two main
elements, a primary separator in the valve
mechanism cover and a filtered canister that is
mounted on the cylinder head. The gases exit the
engine through the valve mechanism cover. The
gases then pass through the primary separator. The
primary separator removes most of the liquid oil from
the gas. The liquid oil is then returned to the engine.
The gas then passes through the filter element
before exiting to atmosphere in an open breather
system or back to the induction system in a closed
breather system via the breather vent pipe.
Any liquid oil that is captured by the filter drains from
the bottom of the canister. The liquid oil is returned by
the drain pipe that runs from the bottom of the
canister back to the crankcase. A valve connects the
drain pipe to the crankcase. This valve prevents the
bypass of gas past the filter and oil from passing up
the drain pipe.
A pressure control valve is located in the top cap of
the canister. This valve regulates the crankcase
pressure on the closed breather system.
A pressure relief valve is located in the rear of the
canister in the integral mounting bracket. Under
normal operation of the engine, this valve will not
operate. If part of the system becomes blocked the
valve will open at a pressure of 8.5 kPa (1.2 psi).
The open valve will allow gas to bypass the filter and
the pipes for venting.
The filter element can be accessed by removing the
top cap of the canister. Refer to Operation and
Maintenance Manual, "Engine Crankcase Breather
Element - Replace" for the correct procedure.
NOTICE
The crankcase breather gases are part of the en-
gines measured emissions output. Any tampering
with the breather system could invalidate the engines
emissions compliance.
23
Engine Operation