Service Manual

ISB, ISBe and QSB (Common Rail [...] Crankcase Blowby, Measure
Section 14 - Engine Testing - Group 14 Page 14-49
To buy Cummins Parts and Service Manuals, Training Guides, or Tools go to our website at https://store.cummins.com
Also, measure exhaust back pressure during exhaust
brake operation.
Operate the engine until a steady reading is obtained.
NOTE: When measuring blowby, the value can “spike”
initially as the engine reaches peak power and rated
speed. Wait for the blowby measurement to stabilize
before taking a reading.
If blowby 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 blowby pressure is above specification during
exhaust brake operation and the exhaust back pressure is
within specification, check the turbocharger blowby
contribution. Reference the turbocharger oil drain isolation
step previously in this procedure.
Remove the engine blowby service tool and the water
manometer, pressure gauge, or transducer.
Remove the pressure gauge used to measure exhaust
back pressure during exhaust brake operation.
Install a plug in the test port.
Base Engine Component Blowby Contribution:
Base engine components can also be contributing factors
of increased crankcase blowby and higher than normal
crankcase pressure. Reference the Crankcase Gases
(Blowby) Excessive troubleshooting symptom tree in
Section TS of the appropriate engine service manual to
evaluate the remaining possible causes for increased
blowby and higher than normal crankcase pressure. The
following are listed as possible base engine component
causes: