Hummer H1 (2006+). Manual - part 177

3-50 Fuel, Emissions, and Exhaust

___________________________________________

Figure 3-32:   Weathercap Mounting

Installation

1.

Install the gasket and air intake duct, secure with the three bolts and washers.

2.

Install the weathercap and secure with three screws.

Drainage Fitting Replacement

Removal

1.

Remove the air cleaner assembly.

2.

Remove the three screws and the drainage fitting from the air intake support (Figure 3-33).

WEATHERCAP

AIR INTAKE

GASKET

SCREW

BOLT

WASHER

DUCT

___________________________________________

 Fuel, Emissions, and Exhaust  3-51

Figure 3-33:   Drainage Fitting Location

Installation

1.

Position the drainage fitting on the air intake support and install the fitting screws (Figure 3-33).

2.

Install the air cleaner assembly.

Central Vent Line Replacement

Removal

Remove the central vent line from the tee fitting and the air cleaner fitting (Figures 3-29 and 3-30).

DRAINAGE FITTING

AIR INTAKE SUPPORT

3-52 Fuel, Emissions, and Exhaust

___________________________________________

.

Figure 3-34:   Central Vent Line Routing

Installation

Install the central vent line on the tee fitting and the air cleaner fitting (Figures 3-29 and 3-30).

.

Figure 3-35:   Central Vent Line Fitting Location

CENTRAL VENT LINE

TEE FITTING

CENTRAL VENT LINE

VENT LINE FITTING

___________________________________________

 Fuel, Emissions, and Exhaust  3-53

Positive Crankcase Ventilation (PCV) Valve 

A crankcase ventilation system is used in order to provide a more complete scavenging of crankcase vapors. There are two PCV
valves, one on each valve cover, that feed crankcase gases from the rocker covers into the turbocharger inlet. At higher engine
speeds crankcase gases are drawn into the turbocharger inlet. At lower speeds, turbo suction is insufficient to draw in the gases.

NOTE:

Oil in the charged air cooler, hoses, turbocharger, or intake manifolds is normal with a closed crankcase ventilation sys-

tem.

The maximum crankcase pressure is 4 kPa or 16 in of water at 3,100 RPM measured at the oil level indicator tube.

Exhaust Gas Recirculation (EGR) System

EGR is used as an emission control technique for reducing oxides of nitrogen (NOx) at the tailpipe. A small amount of exhaust is
recirculated back into the intake manifold to dilute the incoming air charge. This has a cooling effect on combustion temperature
which helps reduce the formation of NOx. The charge is further cooled by a liquid to gas cooler prior to introducing the exhaust
into the intake manifold. The EGR system is monitored by the ECM with the help of a temperature sensor located in the mass air
flow sensor.

EGR Valve

The EGR valve motor is a direct current (DC) stepper motor utilizing a worm gear that extends from the motor to push on the EGR
valve stem  (Figures 3-36 and 3-37). The worm gear is not attached to the valve stem, and can only force the valve open. A return
spring is used to force the valve closed.

Removal

1.

Disconnect the negative battery cable.

2.

Drain the cooling system (Refer to section 4).

3.

Remove the air induction hose (Refer to section 3).

4.

Remove the EGR cooler tube (Refer to section 3).

5.

Remove the EGR valve bolts and remove the EGR valve and discard the EGR valve gasket.

Installation

1.

Install the EGR valve with a new EGR valve gasket and torque to 15 lb-ft. (20 N·m).

2.

Install the EGR cooler tube.

3.

Install the air induction hose and torque the clamps to 35 lb-in. (4 N·m)

4.

Fill and bleed the cooling system.

5.

Connect the negative battery cable.

 Crankcase Ventilation System Inspection/Diagnosis

Concern

Action

PVC check valve stuck closed

Excessive crankcase pressure 
Possible oil leaks. Replace the valve.

Odors

Normal situation

Noise

Cracked hoses

Smoke

Damaged PCV diaphragm

Excessive Oil Consumption

Damaged PCV diaphragm, missing or broken spring