Engine Mechanical - 4.8L, 5.3L & 6.0L: Other GMC Yukon Denali

FUEL PRESSURE RELEASE

Disconnect negative battery cable. Loosen fuel tank cap to relieve tank pressure. Wrap a shop towel around fitting while connecting fuel gauge top avoid spillage. Connect one end of fuel gauge hose to pressure relief fitting on fuel rail. Place other end of hose in a container. Open relief valve to release pressure.

CYLINDER HEAD

Note. Note location of valve train components for installation reference.

Note. Aluminum cylinder heads are used on 4.8L and 5.3L. Cast iron cylinder heads are used on 6.0L.

ROCKER ARMS & PUSHRODS

Note. Note location of valve train components for installation reference.

VALVE LIFTERS

Note. Note valve lifter locations for installation reference.

WATER PUMP

Note. DO NOT immerse water pump in solvent. Solvent may cause premature bearing failure.

OIL PAN

Note. Original oil pan gasket is retained and aligned with rivets. It is not necessary to install new rivets when replacing pan gasket.

Valve Springs

Measure valve spring free length, installed height and pressure (tension). Replace valve spring if measurement is not within specification. See VALVES & VALVE SPRINGS table under ENGINE SPECIFICATIONS. On 4.8L and 5.3L, measure installed valve spring height between top of shim and top of shield. On 6.0L, measure installed spring height between seat and top of spring shield. If height is less than 1.82" (46.25 mm), install shims as necessary to bring installed height to specification.

Valve Stem Oil Seals

Coat seal with engine oil before installation. Using Valve Stem Oil Seal Installer (J-42078), seat seal against valve spring shim (4.8L and 5.3L), or cylinder head spring seat (6.0L). Measure valve stem seal for proper installed height. Measure clearance between top edge of oil seal body and valve spring shim surface (4.8L and 5.3L), or between top edge of oil seal body and valve spring seat surface (6.0L). Clearance should be.712-.752" (18.1-19.1 mm). (Scheme 21)

Valve Guides

Measure valve guide oil clearance. See CYLINDER HEAD table under ENGINE SPECIFICATIONS. If not within specification, ream valve guide to accept oversize sleeve.

Valves

Replace valve if margin is less than 0.05" (1.25 mm). See VALVES & VALVE SPRINGS table.

Scheme 20

Fitting Pistons

Note. A .20" (.50 mm) oversize piston and ring set is available for service.

Measure piston skirt diameter at 90-degree angle to piston pin. Measure cylinder bore diameter 2 1/2" below cylinder block deck. Determine piston clearance. If piston clearance is not within specification, replace piston and/or machine cylinder bore as necessary. See PISTONS, PINS & RINGS and CYLINDER BLOCK tables under ENGINE SPECIFICATIONS. When installing piston pin, ensure pin protrudes.05" (1.27 mm) from side of piston. (Scheme 22) Install pistons with alignment mark facing front of engine.

Piston Rings

Measure piston ring end gap and side clearance. If measurements are not within specification, replace piston and/or rings as necessary. See PISTONS, PINS & RINGS table. under ENGINE SPECIFICATIONS. Install compression rings, with mark on ring facing upward. Stagger compression ring end gaps a minimum of 1.0" (25 mm). Oil control rings do not have mark and may be installed in either direction. Stagger oil ring end gaps a minimum of 90 degrees.

Scheme 21

Rod Bearings

Measure rod bearing journal out-of-round, taper and oil clearance. If measurement is not within specification, replace rod bearings and/or machine crankshaft. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS. Ensure rod side play is within specification.

Crankshaft & Main Bearings

1. Mark bearing caps for reassembly. Measure journal diameter, out-of-round, taper and oil clearance. If measurements are not within specification, replace main bearings and/or machine crankshaft. See «CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS»(ref-97542-S06466902622001050800000) table under ENGINE SPECIFICATIONS. Align thrust bearing surfaces, and measure crankshaft end play. See «THRUST BEARING»(ref-97542-S13799063432001050800000). If end play exceeds.0015-.0078" (.04-.20 mm), replace thrust bearings. NOTE: To properly align crankshaft thrust bearings, crankshaft final thrust must be in forward direction.
2. Using Crankshaft Bearing Cap Remover (J-41818) and Slide Hammer (J-6125-B), carefully remove caps for service. Install main bearings and main caps. Tap bearing caps into cylinder block cavity using a plastic hammer. DO NOT use cap bolts to pull crankshaft bearing caps into seats. Install NEW main cap side bolts (M8). Tighten main cap bolts in sequence and to specification. see scheme 23 See «TORQUE SPECIFICATIONS»(ref-97542-S25419399842001050800000). When installing main bearings, ensure locating tab on bearings are aligned with locating notches in cylinder block journal bore and bearing caps.

Thrust Bearing

Install main bearing caps (except rear), and tighten cap bolts to specification. See TORQUE SPECIFICATIONS . Install rear main bearing cap and tighten cap bolts to 10 ft. lbs. (14 N.m). Tap crankshaft rearward then forward to align thrust surfaces. Tighten rear main bearing cap bolts to specification. Measure crankshaft end play at forward thrust surface of rear main bearing cap. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS.

Cylinder Block

Maximum deck surface warpage is .008" (.22 mm). If warpage exceeds specification, machine surface. Measure cylinder bore out-of-round and taper. If measurement is not within specification, machine cylinder bore and/or replace piston. See CYLINDER BLOCK table under ENGINE SPECIFICATIONS.

Scheme 22

Oil Pressure

Measure oil pressure with engine at operating temperature and specified RPM. On all engines, oil pressure is 6 psi (.4 kg/cm 2 ) @ 1000 RPM, 18 psi. (1.3 kg/cm 2 ) @ 2000 RPM, and 24 psi. (1.7 kg/cm 2 ) @ 4000 RPM.