Head Gasket - Single

Complete cylinder head gasket replacement for the 2018-2024 Honda Accord 1.5L turbo engine, including cylinder head removal, surface preparation, and reassembly with new gasket.

Warnings

Tools required

Parts

• Cylinder head gasket × 1 — Use OEM Honda gasket
• Cylinder head bolts (set of 10) × 1 — Use OEM torque-to-yield bolts
• Valve cover gasket × 1 — Use OEM specification
• Exhaust manifold gasket × 1 — Use OEM specification
• Intake manifold gasket × 1 — Use OEM specification
• Spark plugs × 4 — NGK DILKAR8A8 or equivalent
• Engine oil and filter × 1 — Use OEM oil filter
• Turbocharger coolant line gaskets × 2 — Use OEM specification
• Timing chain tensioner gasket × 1 — Use OEM specification

Fluids

• Honda Type 2 Coolant (Blue) — 6 qt
• Honda Genuine 0W-20 — 4 qt

Preparation

1. Ensure engine is completely cold. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery terminal and wait 3 minutes for SRS system discharge
3. Remove engine cover by pulling upward on retaining clips
4. Drain engine coolant completely from radiator drain plug and block drain plug into appropriate container
5. Drain engine oil and remove oil filter
6. Remove front bumper cover to access intercooler and charge pipe connections
7. Label and photograph all vacuum lines, electrical connectors, and hose routing for reassembly reference

Procedure

1. 1

   Remove intake system and turbocharger components
   Remove air intake tube, intercooler, and charge pipes. Disconnect turbocharger oil feed and return lines. Remove turbo heat shield. Disconnect wastegate actuator vacuum line. Support turbocharger but leave attached to exhaust manifold for now.
2. 2

   Remove accessory components and wiring
   Disconnect ignition coils and remove all four coils. Remove spark plugs. Disconnect fuel injector harness and engine wiring harness connectors at cylinder head. Remove throttle body coolant hoses. Disconnect PCV hose and breather tube from valve cover.
3. 3

   Remove valve cover
   Remove valve cover bolts in reverse of tightening sequence (outer bolts first, then inner). Carefully lift valve cover off, breaking gasket seal if necessary. Inspect camshafts and rocker arms for damage or abnormal wear.
4. 4

   Set engine to TDC and lock timing
   Rotate crankshaft clockwise using crankshaft pulley bolt until No. 1 piston is at TDC compression stroke. Verify camshaft timing marks align with cylinder head surface. Install camshaft holding tool to lock camshafts in position. Mark timing chain to camshaft sprocket relationship with paint marker.
5. 5

   Remove timing chain components
   Remove timing chain tensioner (do not allow tensioner to extend). Remove timing chain guide (if accessible from this side). Carefully remove camshaft sprocket bolts while holding camshafts with holding tool. Remove camshaft sprockets while maintaining timing chain support - do not allow chain to fall into chain case. Secure timing chain with wire to prevent dropping.
6. 6

   Remove camshafts
   Loosen camshaft cap bolts in reverse order of tightening sequence, gradually in 2-3 passes to release valve spring tension evenly. Remove camshaft caps, keeping them in order. Carefully lift out intake and exhaust camshafts. Inspect camshaft journals and lobes for scoring or wear.
7. 7

   Remove intake and exhaust manifolds
   Disconnect exhaust downpipe from turbocharger. Remove exhaust manifold/turbocharger assembly as a unit (6 nuts to cylinder head). Remove intake manifold bolts and carefully separate intake manifold from cylinder head. Plug all openings to prevent debris entry.
   Torque spec

   Exhaust Manifold Nuts25 Nm (18 lb-ft)

   Intake Manifold Bolts25 Nm (18 lb-ft)
8. 8

   Support engine and remove cylinder head
   Install engine support fixture or attach engine hoist to lift eyes on engine. Disconnect remaining coolant hoses from cylinder head (heater hoses, coolant bypass). Remove cylinder head bolts in reverse of tightening sequence (outer bolts first, progressing to center). Carefully lift cylinder head straight up off block. Do not pry between head and block surfaces.
   ⚠Cylinder head weighs approximately 40 lbs. Use proper lifting technique or get assistance.
   Torque spec

   Cylinder Head Bolts - Step 140 Nm (30 lb-ft)
9. 9

   Inspect and clean mating surfaces
   Remove old head gasket from block. Use plastic gasket scraper to carefully clean all gasket material from cylinder head and block surfaces - DO NOT use metal scrapers that can gouge aluminum. Clean surfaces with brake cleaner and lint-free rags. Inspect cylinder head for warpage using straightedge and feeler gauge - maximum warpage is 0.05mm (0.002 inch). Check block surface similarly. If warpage exceeds specification, cylinder head must be machined or replaced.
   ⚠Any scratches or gouges in sealing surfaces will cause head gasket failure. Work carefully and inspect thoroughly.
10. 10

    Inspect cylinder bores and pistons
    With head removed, inspect cylinder bore surfaces for scoring or ridge wear. Check pistons for damage, carbon buildup on tops. Verify no debris has fallen into cylinders. Stuff clean rags into cylinder bores to prevent debris entry during reassembly preparation.
11. 11

    Install new head gasket and cylinder head
    Remove rags from cylinders and wipe bores clean one final time. Install new cylinder head gasket on block with orientation marks facing up (TOP or OPEN marks). Verify all coolant and oil passages align. Carefully lower cylinder head onto block, aligning dowel pins. Install NEW cylinder head bolts finger-tight in sequence from center outward.
    ⚠️Head gasket orientation is critical. Installing upside down will cause immediate engine failure.
12. 12

    Torque cylinder head bolts
    Using proper sequence (center outward), torque all cylinder head bolts to 30 Nm (22 lb-ft). Then, in same sequence, use angle gauge to rotate each bolt an additional 130 degrees. Verify all bolts have been angle-torqued before proceeding.
    ⚠Torque-to-yield bolts must be tightened in two stages: torque specification first, then angle rotation. Do not skip or reverse these steps.
    Torque spec

    Cylinder Head Bolts - Step 140 Nm (30 lb-ft)
13. 13

    Install camshafts and set timing
    Lubricate camshaft journals and lobes with clean engine oil. Install camshafts in correct positions (intake and exhaust marked on cam ends). Install camshaft caps in correct positions and orientation. Tighten camshaft cap bolts gradually in proper sequence to 15 Nm (11 lb-ft). Install camshaft sprockets aligning with timing marks made during disassembly. Verify timing chain alignment marks match.
14. 14

    Complete timing chain reassembly
    Install new timing chain tensioner gasket and install tensioner. Remove camshaft holding tool. Manually rotate engine two complete revolutions clockwise and verify timing marks realign perfectly at TDC. If timing is off, stop and correct immediately before proceeding.
15. 15

    Reassemble remaining components
    Install intake manifold with new gasket and torque bolts to specification. Install exhaust manifold/turbocharger assembly with new gasket and torque nuts to specification. Reconnect turbo oil lines and coolant lines with new gaskets. Install new valve cover gasket and torque valve cover bolts to specification. Install spark plugs and ignition coils. Reconnect all electrical connectors, vacuum lines, and hoses per photographs. Reinstall intercooler and intake piping.
    Torque spec

    Intake Manifold Bolts25 Nm (18 lb-ft)

    Exhaust Manifold Nuts25 Nm (18 lb-ft)

Reassembly

1. Refill cooling system with Honda Type 2 coolant, bleeding air from system using radiator cap and bleed valve
2. Fill engine with 4 quarts of Honda Genuine 0W-20 oil and new oil filter
3. Reconnect battery negative terminal
4. Double-check all connections, hoses, and fasteners before starting engine
5. Reinstall front bumper cover and engine cover

Verification

• Start engine and verify it starts smoothly without unusual noises or valve train clatter
• Monitor for any coolant, oil, or exhaust leaks while engine warms to operating temperature
• Verify cooling fans cycle properly and engine reaches normal operating temperature without overheating
• Check for any vacuum leaks (rough idle or high idle condition)
• Allow engine to idle for 10-15 minutes, then check coolant level and top off as needed
• Test drive vehicle and verify normal power, boost pressure, and no check engine lights
• Recheck all fluid levels after test drive and inspect for any new leaks
• After 500 miles, recheck valve cover and intake/exhaust manifold bolts for proper torque retention

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