Hummer H3. Manual — part 307

Fig. 96: Checking For TDC Position (Method 2)
Courtesy of GENERAL MOTORS CORP.

41. Second Method-Rotate the crankshaft in the engine rotational direction clockwise until the

number 1 piston is at TDC on the compression stroke. The word Delphi on the exhaust
camshaft position actuator will be parallel with the cylinder head to cam cover mating
surface. When the piston is at TDC, the flats at the rear of the camshafts will be facing up
and level when using a straight edge across the camshaft flats. A 0.005 inch feeler gage
should not slide under the straight edge (1).

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

Fig. 97: Locking Flywheel With Special Tools
Courtesy of GENERAL MOTORS CORP.

42. Once TDC is located for the number 1 cylinder using above methods, raise the vehicle and

lock the flywheel with the EN 46547 . See Special Tools.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

Fig. 98: View Of Reference Mark On Harmonic Balancer
Courtesy of GENERAL MOTORS CORP.

43. Use a white paint pen or equivalent to place a reference mark on the harmonic balancer to

the front cover for alignment purposes.

44. Lower the vehicle.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

Fig. 99: Securing Camshafts
Courtesy of GENERAL MOTORS CORP.

45. Install J 44221 to the back of the camshafts. See Special Tools.

CAUTION: The camshaft holding tools must be installed on the

camshafts to prevent camshaft rotation. When performing
service to the valve train and/or timing components, valve
spring pressure can cause the camshafts to rotate
unexpectedly and can cause personal injury.

IMPORTANT: If the timing is correct (TDC compression stroke number 1

cylinder), the camshaft flats will be in the up position.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3