Choose the appropriate blow by measurement service tool to use for the engine being serviced. Reference the
Mid Range Blow by Specifications Chart in this procedure and determine the appropriate blow by measurement
service tool to use, based on engine type and/or horsepower.
NOTE: Either service tool can be used to measure blow by as long as the blow by measurement is correctly matched
to the correct flow rate. Reference the flow rate conversion tables in this procedure for the correct orifice.
To measure the crankcase blow by pressure, connect a water manometer, Part Number ST1111-3, pressure
gauge, or transducer to the blow by measurement service tool.
NOTE: The location of the crankcase breather tube can vary by engine configuration (front gear train or rear gear
train) and/or application (Marine, Industrial, and Automotive). See Section E (Engine Identification) for
crankcase breather tube locations.
Install the appropriate blow by service tool(s):
• For typical open crankcase breather/ventilation systems, connect the appropriate blow by service tool to the end of the crankcase breather tube. Connect a water manometer pressure gauge or transducer to the blow by service tool.
• For engines with closed crankcase ventilation systems (without a crankcase ventilation filter), disconnect the
breather tube and plug the intake manifold or turbocharger compressor housing port. Connect the appropriate blow by service tool to the end of the crankcase breather tube. Connect a water manometer pressure gauge or transducer to the blow by service tool.
• For crankcase breather/ventilation systems with crankcase ventilation filters, follow the proceeding
steps on connecting the blow by measurement equipment.
For ISB CM2150 engines that have the crankcase ventilation filter located on top of the rocker lever cover,
use the following steps to connect the blow by measurement tools.
• Disconnect the crankcase ventilation line from the turbocharger/OEM intake plumbing. If the crankcase
ventilation line is connected to the turbocharger housing, remove the inlet fitting.
• If the crankcase ventilation line is connected to the turbocharger housing, install a straight thread plug,
Part Number 3089567. Plug the crankcase ventilation line with a suitable fitting.
NOTE: If the crankcase ventilation line is connected to the OEM intake plumbing (not shown), use a suitable fitting
to plug the port in the intake plumbing. Also plug the crankcase ventilation line coming from the engine with a
suitable fitting.
• Remove the oil fill cap from the rocker lever cover. Install an oil fill adapter, Part Number 3990099.
• Connect the appropriate blow by service tool to the outlet of the oil fill adapter. Connect a water
manometer, pressure gauge, or transducer to the blow by service tool.
For ISB CM2150 engines that have the crankcase ventilation filter located at the rear of the engine, use the
following steps to connect the blow by measurement tools.
• Disconnect the crankcase ventilation line from the crankcase ventilation filter housing. Plug or cap the
crankcase ventilation filter housing.
• Connect the appropriate blow by service tool to the crankcase ventilation line exiting the flywheel housing.
Connect a water manometer, pressure gauge, or transducer to the blow by. service tool.
For ISC and ISL CM2150 engines, use the following steps to connect the blow by measurement tools.
• Remove the oil fill cap from the rocker lever cover.
Install an oil fill adapter, Part Number 3990099.
• Connect the appropriate blow by service tool to the outlet of the oil fill adapter. Connect a water
manometer, pressure gauge, or transducer to the blow by service tool.
• Use a suitable fitting to plug the crankcase breather tube.
Engine Blow by Contribution:
Operate the engine at rated speed and under load by either:
• For engine run-in, a chassis dynamometer or engine dynamometer.
• For engine testing, a chassis dynamometer or engine dynamometer.
• A stall speed test (for engines equipped with automatic transmissions only).
Operate the engine at rated rpm and full load until a steady reading is obtained.
NOTE: When measuring blow by, the value can “spike” initially as the engine reaches peak power and rated
speed. Wait for the blow by measurement to stabilize before taking a reading.
NOTE: For engine run-in, if a sudden increase in blow by occurs, or if blow by exceeds the maximum allowable limit
during any run-in step, return to the previous step and continue the run-in. If blow by does not reach an
acceptable level, discontinue the run-in and determine the cause.
Record the steady blow by measurement.
Remove the engine blow by service tool and water manometer or pressure gauge if the blow by is within
specification.
Preferred Turbocharger Isolation Method:
Install a hose assembly with two shutoff valves (A and B), installed as shown in the illustration, between the
turbocharger and turbocharger drain line location in the cylinder block. The valves must have a minimum inside
diameter of 19 mm [0.75 in]. Place the other hose in a 8 to 9 liter [2 to 3 gal] container.
NOTE: Some turbocharger oil drain tubes are a single one piece tube. It can be necessary to create a turbocharger
isolation tool. Use a new or used turbocharger drain line and cut a middle section out of the turbocharger drain line
to fit the check valves and hoses.
Close the valve (A) that allows oil to drain into the bucket.
Open the valve (B) that allows oil to drain into the engine.
Operate the engine at rated speed and under load by either:
• For engine testing, a chassis dynamometer or engine dynamometer
• A stall speed test (for engines equipped with automatic transmissions only).
Operate the engine at rated rpm and full load until a steady reading is obtained.
NOTE: When measuring blow by, the value can “spike” initially as the engine reaches peak power and rated
speed. Wait for the blow by measurement to stabilize before taking a reading.
Continue operating at rated speed and load.
Open valve (A) and close valve (B).
Record the blow by pressure reading.
Alternate Turbocharger Isolation Method:
With the turbocharger oil drain line disconnected from the cylinder block, run the turbocharger drain line into a large container.
Plug the turbocharger oil drain port in the cylinder block.
Operate the engine at rated speed and under load by either:
• For engine testing, a chassis dynamometer or engine dynamometer
• A stall speed test (for engines equipped with automatic transmissions only).
Record the peak blow by pressure measurement.
Determine the turbocharger blow by pressure contribution by determining the difference in the blow by pressure measurement with the turbocharger drain isolated, valve (A) open, and turbocharger drain not isolated, valve (A) closed.
Check·the engine oil level and add oil if necessary.
Air Compressor Blow by Contribution:
With the engine blow by service tool and water manometer or pressure gauge still installed, isolate the air
compressor, if equipped, to determine if there is internal damage to the air compressor contributing to high engine
crankcase pressure. The air compressor can be isolated by unloading the air compressor.
With the engine shut OFF, bleed the vehicle’s air system down by opening the drain cock on the wet tank to release
compressed air from the system.
NOTE: The air compressor governor/unloader location can vary on each engine application. The air governor/
unloader can be air compressor mounted or chassis mounted.
Disconnect the air signal line from the air compressor governor/unloader air signal port.
Disconnect the air compressor discharge line and air intake hose from the air compressor.
NOTE: On turbocharged air compressors, make sure to plug the air intake hose connected to the engine intake
manifold or the engine will not reach full power during test.
To unload the air compressor, determine the pressure needed at the governor/unloader air signal port to start
and stop the air compressor from pumping.
NOTE: Typical 621 kPa [90 psi) of air pressure is the set point between starting and stopping of the air compressor
pumping. Refer to the OEM service manual.
Connect a regulated shop air pressure line, with pressure gauge, to the air compressor governor/unloader air signal
port.
NOTE: When performing the test, make sure that the air system pressure does not exceed the manufacturer’s
maximum allowable pressure.
Run the engine and increase the signal pressure to the air governor/unloader to determine when the air compressor
will stop pumping (system pressure stops rising at this point). Record the signal line pressure.
Reduce the signal pressure to determine when system pressure starts the air compressor pumping again (system
pressure will begin to rise again at this point). Record the signal line pressure.
NOTE: Allow the air compressor to pump long enough to build enough pressure in the system to release and
operate the air brakes.
With the regulated shop air pressure line still connected to the air compressor governor/unloader air signal port,
regulate the signal pressure so that the air compressor starts pumping (system pressure will begin to rise again
at this point). Use the pressure value recorded previously as a set point.
Operate the engine at rated speed and under load by either:
• For engine testing, a chassis dynamometer or engine dynamometer.
• A stall speed test (for engines equipped with automatic transmissions only).
Operate the engine at rated rpm and full load until a steady reading is obtained.
NOTE: When measuring blow by, the value can “spike” initially as the engine reaches peak power and rated
speed. Wait for the blow by measurement to stabilize before taking a reading.
Continue operating the engine at rated speed and load.
Increase the signal pressure (system pressure stops rising at this point). Use the pressure value recorded previously
as a set point.
Operate the engine at rated rpm and full load until a steady reading is obtained.
NOTE: When measuring blow by, the value can “spike” initially as the engine reaches peak power and rated
speed. Wait for the blow by measurement to stabilize before taking a reading.
Determine the air compressor blow by pressure contribution by determining the difference in the blow by
pressure measurement with the air compressor pumping and the air compressor not pumping.
With the engine shut OFF, bleed the vehicle’s air system down by opening the drain cock on the wet tank to release
compressed air from the system.
Disconnect the regulated shop air pressure line, with pressure gauge, from the air compressor governor/
unloader air signal port.
Connect the air signal line. Refer to the OEM service manual.
Remove the engine blow by service tool and water manometer or pressure gauge if the blow by is within
specification.
NOTE: On turbocharged air compressors, make sure to remove the plug previously installed in the air intake hose
connected to the engine intake manifold.
Connect the air compressor discharge line and air intake hose from the air compressor.
Exhaust Brake Blow by Contribution:
NOTE: Not all vehicles are equipped with an exhaust brake.
With the engine blow by service tool and water manometer or pressure gauge still installed, measure blow by pressure during exhaust brake operation, if equipped.
Operate the vehicle going down a long inclined road such as a highway or interstate off ramp. Begin exhaust brake
operation at rated engine speed while measuring blow by pressure during exhaust brake operation.
Also, measure exhaust back pressure during exhaust brake operation.
Operate the engine until a steady reading is obtained.
NOTE: When measuring blow by, the value can “spike” initially as the engine reaches peak power and rated
speed. Wait for the blow by measurement to stabilize before taking a reading.
If blow by pressure is above specification during exhaust brake operation and exhaust back pressure is above
specification, repair or replace the exhaust brake. See the manufacturer’s instructions.
If the blow by pressure is above specification during exhaust brake operation and the exhaust back pressure
is within specification, check the turbocharger blow by contribution. Reference the turbocharger oil drain isolation step previously in this procedure.
Remove the engine blow by service tool and water manometer or pressure gauge.
Remove the pressure gauge used to measure exhaust back pressure during exhaust brake operation.
Install a plug in the test port.
