Hummer H2. Manual — part 1843

Fig. 540: View Of MAP Sensor
Courtesy of GENERAL MOTORS CORP.

10. Install the MAP sensor (714).

11. Install the EVAP solenoid, bolt, and isolator.

Tighten: Tighten the EVAP solenoid bolt to 10 N.m (89 lb in).

EXHAUST MANIFOLD CLEANING AND INSPECTION

NOTE:

Refer to Fastener Notice in Cautions and Notices.

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 541: Exhaust Manifold & Heat Shield
Courtesy of GENERAL MOTORS CORP.

1. Clean the exhaust manifold (600) and heat shield (603) in solvent.

2. Dry the exhaust manifold with compressed air.

3. Inspect the exhaust manifold-to-cylinder head gasket surface for excessive scratches or gouging.

4. Inspect for a loose or damaged heat shield (603).

5. Inspect the take down studs for damaged threads.

IMPORTANT: Do not use the exhaust manifold-to-cylinder head gaskets again. Upon

installation of the exhaust manifold, install a NEW gasket. An improperly
installed gasket or leaking exhaust system may effect On-Board
Diagnostics (OBD) II system performance.

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 542: Measuring Exhaust Manifold To Cylinder Head For Warpage
Courtesy of GENERAL MOTORS CORP.

6. Use a straight edge and a feeler gauge and measure the exhaust manifold cylinder head deck for warpage.

An exhaust manifold deck with warpage in excess of 0.25 mm (0.01 in) within the two front or two rear
runners or 0.5 mm (0.02 in) overall, may cause an exhaust leak and may effect OBD II system
performance. Exhaust manifolds not within specifications must be replaced.

COOLANT AIR BLEED PIPE CLEANING AND INSPECTION

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

Fig. 543: View Of Pipe & Cover Gasket
Courtesy of GENERAL MOTORS CORP.

1. Remove the sealing gaskets from the pipe.

2. Remove the sealing gaskets from the covers.

IMPORTANT: Do not use the engine coolant air bleed pipe and cover gaskets again.

Upon installation of the pipe and covers, install NEW gaskets.

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2