Head Gasket - Single

This procedure covers replacement of a single cylinder head gasket on the 2014-2018 Chevrolet Silverado 1500 with the 5.3L V8 EcoTec3 L83 engine, including removal and reinstallation of the affected cylinder head, timing components, and related systems.

Warnings

Tools required

Parts

• Cylinder head gasket (MLS multi-layer steel) × 1 — Use OEM GM part number
• Cylinder head bolts (TTY) × 10 — GM 12620219 or equivalent
• Valve cover gasket × 1 — Use OEM specification
• Valve cover grommets × 1 — Use OEM specification
• Exhaust manifold gasket × 1 — Use OEM specification
• Intake manifold gaskets × 1 — Use OEM specification
• Thermostat housing gasket/O-ring × 1 — Use OEM specification
• Timing cover gasket × 1 — Use OEM specification
• Oil drain plug crush washer × 1 — Standard M14 copper washer
• High-temperature thread sealant × 1 — Loctite 565 or equivalent
• RTV silicone sealant (black) × 1 — GM 12378521 or equivalent
• Anti-seize compound × 1 — Copper or nickel-based

Fluids

• ACDelco DEX-COOL (Orange) — 18 qt
• ACDelco dexos1 0W-20 — 8.5 qt

Preparation

1. Park vehicle on level surface, engage parking brake, and place wheel chocks behind rear wheels
2. Disconnect negative battery cable and secure away from terminal
3. Remove engine cover by lifting upward at four attachment points
4. Drain cooling system completely by opening radiator petcock and removing radiator cap when cool
5. Drain engine oil and remove oil filter
6. Relieve fuel system pressure by removing fuel pump fuse and running engine until it stalls
7. Label and photograph all electrical connections, vacuum lines, and hose routing for reassembly reference
8. Support engine from above using engine hoist with load leveler, or install engine support fixture across fender rails

Procedure

1. 1

   Remove intake manifold assembly
   Disconnect throttle body electrical connector and remove air intake duct. Disconnect all fuel lines using appropriate disconnect tools. Remove brake booster vacuum hose from rear of intake manifold. Disconnect PCV hoses and MAP sensor electrical connector. Remove intake manifold bolts in reverse of tightening sequence (outside to inside). Carefully lift intake manifold assembly away and cover open ports with clean shop towels to prevent debris entry.
   Torque spec

   Intake Manifold Bolts25 Nm (18 lb-ft)
2. 2

   Remove valve cover and rocker arm assembly
   Disconnect ignition coil electrical connectors and remove all ignition coils. Disconnect valve cover wiring harness and set aside. Remove valve cover bolts in sequence and carefully separate valve cover from cylinder head (may require light tapping with rubber mallet). Remove rocker arm bolts and rockers while keeping them organized by cylinder number for reinstallation in original positions. Remove pushrods and store vertically in organized rack or numbered holder.
3. 3

   Remove exhaust manifold
   Spray all exhaust manifold studs with penetrating oil and allow to soak for 15-30 minutes. Disconnect oxygen sensor electrical connectors. Remove exhaust manifold heat shield bolts. Disconnect exhaust pipe from manifold at flange (may require cutting if severely corroded). Remove exhaust manifold nuts working from center outward to hot-to-cold pattern. Remove manifold and inspect studs for damage.
   ⚠Exhaust studs are prone to breakage. Use penetrating oil and work slowly. Broken studs require drilling and extraction which adds significant time.
   Torque spec

   Exhaust Manifold Nuts25 Nm (18 lb-ft)
4. 4

   Remove accessory drive components and timing cover
   Remove serpentine belt by rotating tensioner counterclockwise. Remove power steering pump with lines attached and secure aside. Remove alternator and set aside. Install harmonic balancer holding tool and remove balancer bolt (large 24mm bolt, clockwise to loosen). Use harmonic balancer puller to remove balancer from crankshaft. Remove timing cover bolts and carefully pry cover away from engine block (break RTV seal). Remove cover and old gasket material.
   ⚠Do not pry on timing cover excessively as it can crack the aluminum casting. Use plastic pry tools at designated pry points only.
5. 5

   Remove timing chain and camshaft components
   Rotate crankshaft to TDC position for cylinder #1 (timing marks aligned on cam and crank sprockets). Compress timing chain tensioner using small screwdriver and insert retaining pin or paperclip to hold compressed. Remove tensioner bolt and remove tensioner. Remove timing chain guide bolts and guides. Remove camshaft sprocket bolt while holding camshaft with wrench on hex section (between lobes). Remove camshaft sprocket and timing chain together. Remove camshaft bearing cap bolts in reverse sequence (outside to inside) in multiple passes. Remove camshaft bearing caps and carefully lift camshaft from head. Store camshaft on clean surface with lobes not touching anything.
   ⚠️Mark timing chain orientation and sprocket alignment before removal. Improper timing during reassembly will cause catastrophic engine damage.
   ⚠Do not allow camshaft lobes to rest directly on hard surfaces as this will damage the hardened surface finish.
6. 6

   Remove cylinder head bolts and head
   Remove cylinder head bolts in reverse of tightening sequence (outside bolts first, working inward) in multiple passes to avoid warping. Discard all head bolts as they are TTY and cannot be reused. Carefully break head loose from block using plastic mallet or pry points (if equipped). Lift cylinder head straight up to avoid damage to deck surface. Place head on clean padded surface with combustion chambers facing up. Cover cylinders with clean towels to prevent debris entry.
   ⚠Cylinder head weighs approximately 60 pounds. Use proper lifting technique or have assistance available to avoid injury or dropping the head.
   Torque spec

   Cylinder Head Bolts - Step 140 Nm (30 lb-ft)
7. 7

   Clean and inspect surfaces
   Remove all old gasket material from cylinder head and engine block deck surfaces using plastic gasket scraper. Clean surfaces with brake cleaner and lint-free towels. Inspect cylinder head deck surface for warpage using precision straight edge and feeler gauge at multiple points. Maximum allowable warpage is 0.002 inches over any 6-inch span. Check head for cracks using dye penetrant or magnaflux if available. Clean oil return passages in block and head. Verify all cylinder head bolt holes in block are clean and dry (use compressed air and brake cleaner).
   ⚠Any metal scrapers can gouge aluminum surfaces creating leak paths. Use only plastic scrapers on gasket surfaces.
   ℹ️If cylinder head warpage exceeds specification, head must be resurfaced by machine shop. Maximum material removal is 0.008 inches total over head lifetime.
8. 8

   Install new head gasket and cylinder head
   Install new MLS head gasket on engine block with 'TOP' or 'FRONT' marking facing up and toward front of engine. Align all dowel pins and coolant/oil passages. Do not use any sealant on MLS gasket. Carefully lower cylinder head onto block, aligning with dowel pins. Install new cylinder head bolts finger-tight in sequence. Torque head bolts following multi-step sequence: Step 1 - torque all bolts to 40 Nm (30 lb-ft) in sequence, Step 2 - torque all bolts to 80 Nm (59 lb-ft) in sequence, Step 3 - rotate all bolts an additional 90 degrees in sequence using angle gauge.
   ⚠Head bolt sequence is critical. Start with center bolts and work outward in specified pattern found in service manual diagram.
   ⚠If any head bolt does not reach minimum torque or exceeds maximum during angle rotation, stop and investigate. Bolt may be bottoming in hole or threads may be damaged.
9. 9

   Install camshaft and timing components
   Lubricate camshaft lobes and journals with assembly lube or engine oil. Carefully install camshaft into cylinder head. Install camshaft bearing caps in original positions with arrows pointing toward front of engine. Tighten bearing cap bolts in sequence from center outward in three passes to final torque of 14 Nm (10 lb-ft). Verify camshaft rotates freely. Install timing chain guides and torque bolts. Install crankshaft sprocket if removed. Position camshaft sprocket with timing mark at top. Install timing chain over crankshaft sprocket first, then over camshaft sprocket while aligning timing marks. Install camshaft sprocket bolt while holding camshaft hex and torque to 80 Nm (59 lb-ft). Release timing chain tensioner by removing retaining pin. Verify timing marks are still aligned and chain has proper tension.
   ⚠️Double and triple-check timing mark alignment before proceeding. Engine damage will occur immediately upon startup if timing is incorrect.
10. 10

    Install timing cover and front accessories
    Clean timing cover mating surfaces thoroughly. Apply thin bead of RTV sealant to block at parting lines between block and oil pan. Install new timing cover gasket and position cover onto block. Install cover bolts and torque to 20 Nm (15 lb-ft) in criss-cross pattern. Allow RTV to cure per manufacturer instructions (typically 15-30 minutes). Install harmonic balancer onto crankshaft, ensuring keyway is aligned. Install balancer bolt and torque while holding balancer with holding tool. Reinstall alternator, power steering pump, and serpentine belt.
11. 11

    Install pushrods and rocker arms
    Install pushrods in original positions, ensuring each seats properly in lifter socket (should be able to rotate pushrod with fingers). Apply engine oil to rocker arm pivot points and valve stem tips. Position rocker arms on cylinder head ensuring pushrods are properly seated in rocker arm pockets. Rotate crankshaft to position each camshaft lobe to base circle (pointing away from lifter) before tightening corresponding rocker bolt. Torque rocker arm bolts to 30 Nm (22 lb-ft) only when cam lobe is on base circle for that cylinder.
    ⚠Tightening rocker arm bolts when cam lobe is at peak lift will bend pushrods or damage rocker arms. Verify lobe position for each cylinder before torquing.
12. 12

    Install valve cover
    Clean valve cover and cylinder head mating surfaces thoroughly with brake cleaner. Install new valve cover gasket and grommets in valve cover (not on head). Apply small dab of RTV at front corners where timing cover meets cylinder head. Position valve cover onto head and install bolts finger-tight. Torque valve cover bolts in sequence from center outward to 10 Nm (7 lb-ft). Reconnect valve cover wiring harness. Install ignition coils and torque bolts. Connect ignition coil electrical connectors.
13. 13

    Install exhaust manifold
    Clean exhaust manifold mating surface and cylinder head surface. Inspect exhaust studs and replace any that are damaged. Apply anti-seize compound to all exhaust studs (avoid getting on gasket surface). Install new exhaust manifold gasket. Position exhaust manifold and install nuts finger-tight. Torque exhaust manifold nuts to 30 Nm (22 lb-ft) working from center outward in hot-to-cold pattern. Install heat shield and torque bolts. Reconnect exhaust pipe to manifold with new gasket and hardware. Connect oxygen sensor electrical connectors.
    Torque spec

    Exhaust Manifold Nuts25 Nm (18 lb-ft)
14. 14

    Install intake manifold and complete assembly
    Install new intake manifold gaskets on cylinder heads, ensuring all port openings align properly. Clean intake manifold mating surface. Position intake manifold onto heads and install bolts finger-tight. Torque intake manifold bolts in sequence from center outward to 25 Nm (18 lb-ft). Reconnect all PCV hoses, MAP sensor, brake booster vacuum line, and fuel lines. Reconnect throttle body connector and install air intake duct. Install new oil filter and fill engine with 8.5 quarts of ACDelco dexos1 0W-20 oil. Fill cooling system with 18 quarts of ACDelco DEX-COOL coolant (may require burping process to remove air pockets).
    Torque spec

    Intake Manifold Bolts25 Nm (18 lb-ft)
15. 15

    Final checks and startup procedure
    Reconnect negative battery cable. Perform visual inspection of all connections, bolts, and hoses. Check that no tools or rags were left in engine compartment. Prime fuel system by cycling ignition on/off three times without cranking. Crank engine and start (may take longer than normal on first start). Monitor for unusual noises, smoke, or leaks. Allow engine to reach operating temperature while monitoring coolant level and temperature gauge. Check for any coolant, oil, or exhaust leaks around all disturbed areas. Perform several gentle acceleration cycles to seat rings and gaskets. Recheck all fluid levels after engine cools.
    ⚠Do not rev engine above 2500 RPM for first 30 minutes of operation to allow gaskets to properly seat and cure.

Reassembly

1. Torque all fasteners in specified sequence and use torque angle gauge for TTY bolts
2. Replace all gaskets, seals, and single-use fasteners with new OEM or equivalent parts
3. Verify timing mark alignment multiple times before completing timing cover installation
4. Bleed cooling system completely to prevent air pockets that can cause overheating
5. Check valve lash after initial startup if equipped with adjustable valves (this engine uses hydraulic lifters and does not require adjustment)

Verification

• Start engine and verify smooth idle with no unusual noises, misfires, or warning lights
• Check for coolant, oil, and exhaust leaks at all disturbed components while engine is at operating temperature
• Verify cooling fans cycle on/off properly and engine maintains normal operating temperature (195-220°F)
• Test drive vehicle under light to moderate load and verify normal power delivery and no hesitation
• Recheck all fluid levels after cool-down and top off as necessary
• Monitor engine oil for coolant contamination (milky appearance) for several days after repair
• Retorque cylinder head bolts after 500 miles (NOT required for this TTY bolt application - this is for reference only)
• Perform compression test on all cylinders if any driveability issues persist - should be 170-210 PSI with no more than 15% variance between cylinders

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