Hummer H2. Manual - part 67

Visually inspect the block. Check suspected areas for cracks using the Dye Penetrant inspection method. Block 
may be checked for cracks using the Magnaflux method.  

Cracks are most commonly found at the bottom of cylinders, main bearing saddles, near expansion plugs and 
between cylinders and water jackets. Inspect lifter bores for damage. Inspect all head bolt holes for damaged 
threads. Threads should be cleaned using tap to ensure proper head bolt torque. Consult machine shop 
concerning possible welding and machining (if required).  

Cylinder Bore Inspection 

Inspect bore for scoring or roughness. Cylinder bore is dimensionally checked for out-of-round and taper using 
dial bore gauge. For determining out-of-round, measure cylinder parallel and perpendicular to the block center 
line. Difference in the 2 readings is the bore out-of-round. Cylinder bore must be checked at top, middle and 
bottom of piston travel area.  

Bore taper is obtained by measuring bore at the top and bottom. If wear has exceeded allowable limits, block 
must be honed or bored to next available oversize piston dimension.  

Cylinder Honing 

Cylinder must be properly honed to allow new piston rings to properly seat. Cross-hatching at correct angle and 
depth is critical to lubrication of cylinder walls and pistons.  

A flexible drive hone and power drill are commonly used. Drive hone must be lubricated during operation. Mix 
equal parts of kerosene and SAE 20W engine oil for lubrication.  

Apply lubrication to cylinder wall. Operate cylinder hone from top to bottom of cylinder using even strokes to 
produce 45 degree cross-hatch pattern on the cylinder wall. DO NOT allow cylinder hone to extend below 
cylinder during operation.  

Recheck bore dimension after final honing. Wash cylinder wall with hot soapy water to remove abrasive 
particles. Blow dry with compressed air. Coat cleaned cylinder walls with lubricating oil.  

Deck Warpage 

Check deck for damage or warped gasket surface. Place a straightedge across gasket surface of the deck. Using 
feeler gauge, measure clearance at center of straightedge. Measure across width and length of cylinder block at 
several points.  

If warpage exceeds specifications, deck must be resurfaced. If warpage exceeds manufacturer's maximum 
tolerance for material removal, replace block.  

Deck Height 

NOTE:

Some manufacturers recommend that a total amount of material (cylinder head 
and cylinder block) can only be removed before components must be replaced. 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Engine Overhaul Procedures

  

Distance from crankshaft center line to block deck is called the deck height. Measure and record front and rear 
main journals of crankshaft. To compute this distance, install crankshaft and retain with center main bearing and 
cap only. Measure distance from crankshaft journal to block deck, parallel to cylinder center line.  

Add one half of main bearing journal diameter to distance from crankshaft journal to block deck. This 
dimension should be checked at front and rear of cylinder block. Both readings should be the same.  

If difference exceeds specification, cylinder block must be repaired or replaced. Deck height and warpage 
should be corrected at the same time.  

Main Bearing Bore & Alignment 

For checking main bearing bore, remove all bearings from cylinder block and main bearing caps. Install main 
bearing caps in original location. Tighten bolts to specification. Using inside micrometer, measure main bearing 
bore in 2 areas 90 degrees apart. Determine bore size and out-of-round. If diameter is not within specification, 
block must be align-bored.  

For checking alignment, place a straightedge along center line of main bearing saddles. Check for clearance 
between straightedge and main bearing saddles. Block must be align-bored if clearance exists.  

Expansion Plug Removal 

Drill hole in center of expansion plug. Remove with screwdriver or punch. Use care not to damage sealing 
surface.  

Expansion Plug Installation 

Ensure sealing surface is free of burrs. Coat expansion plug with sealer. Using wooden dowel or pipe of slightly 
smaller diameter, install expansion plug. Ensure expansion plug is evenly located.  

Oil Gallery Plug Removal 

Remove threaded oil gallery plugs using appropriate wrench. Soft press-in plugs are removed by drilling into 
plug and installing a sheet metal screw. Remove plug with slide hammer or pliers.  

Oil Gallery Plug Installation 

Ensure threads or sealing surface is clean. Coat threaded oil gallery plugs with sealer and install. Replacement 
soft press-in plugs are installed with a hammer and drift.  

CAMSHAFT 

CLEANING & INSPECTION 

Clean camshaft with solvent. Ensure all oil passages are clear. Inspect cam lobes and bearing journals for 
pitting, flaking or scoring. Using micrometer, measure bearing journal O.D. 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Engine Overhaul Procedures

  

Support camshaft at each end with "V" blocks. Position dial indicator with tip resting on center bearing journal. 
Rotate camshaft and note camshaft runout reading. If reading exceeds specification, replace camshaft.  

Check cam lobe lift by measuring base circle of camshaft using micrometer. Measure again at 90-degree angle 
to tip of cam lobe. Cam lift can be determined by subtracting base circle diameter from tip of cam lobe 
measurement.  

Different lift dimensions are given for intake and exhaust cam lobes. Reading must be within specification. 
Replace camshaft if cam lobes or bearing journals are not within specification.  

Inspect camshaft gear for chipped, eroded or damaged teeth. Replace gear if damaged. On camshafts using 
thrust plate, measure distance between thrust plate and camshaft shoulder. Replace thrust plate if not within 
specification.  

CAMSHAFT BEARINGS 

Removal & Installation 

Remove camshaft rear plug. Camshaft bearing remover is assembled with shoulder resting against bearing to be 
removed according to manufacturer's instructions. Tighten puller nut until bearing is removed. Remove 
remaining bearings, leaving front and rear bearings until last. These bearings act as a guide for camshaft bearing 
remover.  

To install new bearings, puller is rearranged to pull bearings toward the center of block. Ensure all lubrication 
passages of bearing are aligned with cylinder block. Coat new camshaft rear plug with sealant. Install camshaft 
rear plug. Ensure plug is even in cylinder block.  

CAMSHAFT INSTALLATION 

Lubricate bearing surfaces and cam lobes with ample amount of Molykote or camshaft lubricant. Carefully 
install camshaft. Use care not to damage bearing journals during installation. Install thrust plate retaining bolts 
(if equipped). Tighten bolts to specification. On overhead camshafts, install bearing caps in original location. 
Tighten bolts to specification. On all applications, check camshaft end play.  

CAMSHAFT END PLAY 

Using dial indicator, check camshaft end play. Position dial indicator on front of engine block or cylinder head. 
Position indicator tip against camshaft. Push camshaft toward rear of cylinder head or engine and adjust 
indicator to zero.  

Move camshaft forward and note reading. Camshaft end play must be within specification. End play may be 
adjusted by relocating gear, shimming thrust plate or replacing thrust plate depending on each manufacturer.  

TIMING CHAINS & BELTS 

TIMING CHAINS 

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Engine Overhaul Procedures

  

Timing chains will stretch during operation. Limits are placed upon amount of stretch before replacement is 
required. Timing chain stretch will alter ignition timing and valve timing.  

To check timing chain stretch, rotate crankshaft to eliminate slack from one side of timing chain. Mark 
reference point on cylinder block. Rotate crankshaft in opposite direction to eliminate slack from remaining side 
of timing chain. Force other side of chain outward and measure distance between reference point and timing 
chain. See Fig. 23 . Replace timing chain and gears if not within specification.  

Fig. 23: Measuring Timing Chain Stretch 

Timing chains must be installed so timing marks on camshaft gear and crankshaft gear are aligned according to 
manufacturer. See Fig. 24 .  

 

1998 Chevrolet Pickup C1500 

GENERAL INFORMATION Engine Overhaul Procedures