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02 05-19

SUBJECT

DATE

Lubrication System - Crankcase Breather Assembly

February 2019

Additions, Revisions, or Updates
Publication Number / Title

Platform

Section Title

Change

Description and
Operation of the
Crankcase Breather
Assembly

DDC-SVC-MAN-0190

GHG17 DD
HD

Removal of the
Crankcase Breather
Assembly

Significant changes to DD HD sections.

Inspection of the
Crankcase Breather
Assembly
Installation of the
Crankcase Breather
Assembly

All information subject to change without notice.

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2 Description and Operation of the Crankcase Breather Assembly

2

Description and Operation of the Crankcase Breather Assembly

The crankcase breather assembly is located below the turbocharger on the right hand side of the cylinder block. The
crankcase breather has the primary task of regulating the pressure in the crankcase as well as cleaning discharged blow-by
gases. The gases from the crankcase contain engine oil that can lead to adverse effects on engine emission levels.
The blow-by gas produced by the engine passes into the blow-by gas inlet in the crankcase breather housing. In the housing,
the blow-by gas flows to the centrifuge. The centrifuge drive gear is driven by pressurized engine oil, causing the centrifuge
to turn. The centrifugal force that is created causes the blow-by gas to be pushed against the inside wall of the housing. The
engine oil contained in the blow-by gas runs along the inside wall downwards, flows to the outlet and back into the oil pan.
The cleaned blow-by gas flows to the breather outlet and then to the atmosphere. The crankcase breather is maintenance free
for the working life of the engine.

1.
2.
3.
4.
5.
6.

Mounting Bolt
Crankcase Breather Outlet
Mounting Gasket
Threaded Fitting
Breather Inlet Tube
Screw

7.
8.
9.
10.
11.

Bracket
Breather Inlet Tube O-ring
Speed Sensor Mounting Screw
Crankcase Breather Speed Sensor
Speed Sensor O-ring

Figure 1. Crankcase Breather Assembly

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All information subject to change without notice.

Copyright © 2019 DETROIT DIESEL CORPORATION

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Removal of the Crankcase Breather Assembly

Remove as follows:
WARNING: PERSONAL INJURY
To avoid injury, never remove any engine component while the engine is running.

WARNING: PERSONAL INJURY
To avoid injury from hot surfaces, wear protective gloves, or allow engine to cool before removing
any component.
1. Shut off the engine, apply the parking brake, chock the wheels, and perform any other applicable safety steps.
CAUTION: ELECTRICAL SHOCK
To avoid injury from electrical shock, use care when connecting battery cables. The magnetic
switch studs are at battery voltage.
2.
3.
4.
5.

Disconnect the batteries.
Open the hood.
If necessary, remove the bumper. Refer to OEM procedures.
Disconnect the crankcase breather speed sensor electrical harness connection from the crankcase breather speed sensor
and unclip the electrical harness from the crankcase breather assembly.
6. Remove the crankcase breather inlet tube from the crankcase breather inlet tube fitting by squeezing the two tabs
together and pulling the crankcase breather inlet tube away from the cylinder block. See graphic below.

All information subject to change without notice.

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3 Removal of the Crankcase Breather Assembly
7. If equipped with a plastic anti-tamper ring, remove the crankcase breather inlet tube from the crankcase breather inlet
tube fitting by squeezing the two tabs together, using flat head screw drivers, and pulling the crankcase breather inlet
tube away from the cylinder block. See graphic below.

8. Remove the four mounting bolts from the crankcase breather assembly and remove crankcase breather from the
cylinder block.
9. Remove and discard the mounting gasket.

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All information subject to change without notice.

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Inspection of the Crankcase Breather Assembly

Inspect as follows:
1. Clean and inspect the mounting gasket surface of the cylinder block and the crankcase breather for damage that will
prohibit a proper seal; repair as necessary.
2. Inspect the crankcase breather inlet tube and inlet tube fittings for damage. Replace as necessary.
3. Inspect the crankcase breather for cracks or damage. Replace the crankcase breather assembly if damage is found.
4. Inspect the crankcase breather speed sensor for cracks or damaged terminals. Repair or replace as necessary.

All information subject to change without notice.

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5 Installation of the Crankcase Breather Assembly

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Installation of the Crankcase Breather Assembly

Install as follows:
1. Install the crankcase breather assembly to the cylinder block with a new mounting gasket and the four mounting bolts.
Torque the bolts to 60 N·m (44 lb·ft).
2. Install the crankcase breather inlet tube by sliding the tube over the fitting at the cylinder block and push toward the
fitting until it locks. See graphic below.

3. Connect the electrical harness connection to the crankcase breather speed sensor and secure the harness.
4. If necessary, install the bumper. Refer to the Original Equipment Manufacturer (OEM) procedures.
CAUTION: ELECTRICAL SHOCK
To avoid injury from electrical shock, use care when connecting battery cables. The magnetic
switch studs are at battery voltage.
5. Connect the batteries.
WARNING: PERSONAL INJURY
Diesel engine exhaust and some of its constituents are known to the State of California to cause
cancer, birth defects, and other reproductive harm.
• Always start and operate an engine in a well ventilated area.
• If operating an engine in an enclosed area, vent the exhaust to the outside.
• Do not modify or tamper with the exhaust system or emission control system.

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All information subject to change without notice.

Copyright © 2019 DETROIT DIESEL CORPORATION

02 05-19

02 05-19

WARNING: PERSONAL INJURY
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level
surface, parking brake is set, and the wheels are blocked.

WARNING: ENGINE EXHAUST
To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area.
Engine exhaust is toxic.
6. Start the engine and check for oil leaks.
7. Close the hood.

All information subject to change without notice.

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