Head Gasket - Single

This procedure covers removal and replacement of the cylinder head gasket on the 2016-2021 Honda Civic 1.5L turbocharged engine, including disassembly of timing components, cylinder head removal, surface preparation, and reassembly with proper torque sequences.

Warnings

Tools required

Parts

• Cylinder head gasket kit × 1 — Use OEM Honda specification
• Cylinder head bolts (torque-to-yield) × 10 — Use OEM Honda specification
• Valve cover gasket × 1 — Use OEM Honda specification
• Timing chain tensioner gasket × 1 — Use OEM Honda specification
• Exhaust manifold gasket × 1 — Use OEM Honda specification
• Intake manifold gasket × 1 — Use OEM Honda specification
• Thermostat housing O-ring × 1 — Use OEM Honda specification
• Engine oil × 1 — Honda 0W-20
• Oil filter × 1 — Use OEM Honda specification
• Spark plugs × 4 — NGK or Denso OEM equivalent

Fluids

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

Preparation

1. Ensure engine is completely cold. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable and wait 3 minutes for system discharge
3. Remove engine cover by pulling upward on front clips
4. Drain engine coolant completely from radiator petcock and engine block drain plug into appropriate container
5. Drain engine oil and remove oil filter
6. Remove front wheels and right side engine splash shield for access to crankshaft
7. Support engine from above using engine support fixture or from below with jack and wood block under oil pan
8. Relieve fuel system pressure by removing fuel pump fuse and running engine until it stalls

Procedure

1. 1

   Remove intake and exhaust systems
   Disconnect air intake tube from turbocharger inlet. Remove intercooler piping. Disconnect exhaust downpipe from turbocharger outlet (3 bolts). Remove heat shields as necessary. Disconnect all vacuum lines, PCV hoses, and breather tubes from intake manifold and valve cover. Remove intake manifold assembly with throttle body attached by removing mounting bolts. Disconnect oxygen sensor electrical connectors.
2. 2

   Remove accessory components and wiring
   Disconnect all electrical connectors from cylinder head area including injectors, ignition coils, camshaft position sensor, VTC actuator, and knock sensor. Label all connectors for reassembly. Remove ignition coils (10mm bolts) and spark plugs. Disconnect fuel rail by releasing fuel line quick-connect and removing fuel rail mounting bolts. Leave injectors attached to fuel rail. Remove any remaining brackets or wiring harnesses attached to cylinder head.
   ⚠Residual fuel pressure may remain even after system relief. Have rags ready when disconnecting fuel lines.
3. 3

   Remove valve cover and upper timing components
   Remove valve cover bolts in reverse of tightening sequence (start from outside, work inward). Remove valve cover and gasket. Rotate crankshaft clockwise to TDC on cylinder #1 (timing marks aligned on camshaft sprockets). Mark timing chain position relative to camshaft sprockets with paint marker. Remove right engine mount and bracket for access. Remove timing chain upper guide and tensioner.
   ℹ️Take clear photos of timing chain alignment before disassembly. This is critical for correct reassembly.
4. 4

   Remove camshafts
   Hold camshaft sprockets using camshaft holding tool. Remove camshaft sprocket bolts (do not allow chain to drop into timing case). Wire sprockets to maintain chain tension and position. Remove camshaft cap bolts in reverse order (outside to inside, in multiple passes). Remove camshaft caps, keeping them in order. Remove intake and exhaust camshafts. Inspect camshaft journals and lobes for damage.
   ⚠Camshaft caps must be installed in original locations and orientations. Mark each cap with cylinder number and position.
5. 5

   Remove cylinder head bolts
   Remove cylinder head bolts in correct reverse sequence (consult service manual diagram - typically starting from outside bolts working toward center in 2-3 passes). Loosen each bolt 1/4 turn at a time to prevent head warping. Once all bolts are loose, remove them completely. Discard all cylinder head bolts as they are torque-to-yield and not reusable.
   ⚠Incorrect bolt removal sequence can warp the cylinder head. Follow the factory sequence exactly.
6. 6

   Remove cylinder head
   Carefully lift cylinder head straight up off engine block. Head may be stuck due to gasket seal - use plastic pry points at designated locations only. Never pry between mating surfaces. Place cylinder head on clean workbench on wooden blocks. Remove and discard old head gasket. Cover engine block opening with clean shop towels to prevent debris entry.
   ℹ️Cylinder head weighs approximately 40 lbs. Use proper lifting technique or have an assistant help.
7. 7

   Inspect and clean mating surfaces
   Using plastic gasket scraper, carefully remove all old gasket material from both cylinder head and engine block surfaces. Clean surfaces thoroughly with brake cleaner. Inspect cylinder head surface with straight edge and feeler gauge at multiple points - maximum warpage allowed is 0.002 inches. Check block surface for damage. Inspect head for cracks using dye penetrant method if overheating was suspected. Verify all coolant and oil passages are clear.
   ⚠Do not use metal scrapers on aluminum surfaces. Use only plastic tools to avoid gouging mating surfaces.
8. 8

   Install new head gasket and position cylinder head
   Ensure both mating surfaces are completely clean and dry. Install new head gasket on block with orientation marks facing up (TOP or OBEN marking visible). Align gasket dowel pins. Verify gasket is correctly positioned over all coolant and oil passages. Carefully lower cylinder head onto block, aligning with dowel pins. Do not slide head once in contact with gasket.
   ⚠Head gasket has specific front/rear and up/down orientation. Installing backwards or upside down will cause immediate failure.
9. 9

   Install and torque cylinder head bolts
   Install all NEW cylinder head bolts finger-tight in their correct positions. Following the factory torque sequence diagram (typically center bolts first, working outward in spiral pattern), torque all bolts to 30 Nm (22 lb-ft) using torque wrench. Using angle gauge, rotate each bolt an additional 130 degrees in the same sequence. Verify all bolts have been angle-torqued by checking witness marks.
   ⚠️Torque-to-yield bolts stretch during tightening. The angle torque step is critical - insufficient torque will cause head gasket failure.
   Torque spec

   Cylinder Head Bolts - Step 140 Nm (30 lb-ft)
10. 10

    Install camshafts and timing components
    Lubricate camshaft journals with clean engine oil. Install intake and exhaust camshafts in correct positions with timing marks properly oriented. Install camshaft caps in original positions with arrow marks pointing toward timing chain side. Torque camshaft cap bolts in sequence (inside to outside) to 15 Nm (11 lb-ft). Install camshaft sprockets, aligning timing chain with reference marks made during disassembly. Torque sprocket bolts to specification. Install timing chain tensioner and upper guide. Remove crankshaft locking pin and rotate engine 2 complete revolutions, verify timing marks realign at TDC.
    ⚠Double-check timing mark alignment before installing valve cover. Incorrect timing will cause severe engine damage on startup.
11. 11

    Install valve cover and remaining components
    Install new valve cover gasket in valve cover groove. Apply small dab of RTV sealant at camshaft cap corners. Install valve cover and torque bolts in sequence (center outward) to 13 Nm (10 lb-ft). Install right engine mount bracket and mount. Install intake manifold with new gasket, torque bolts evenly to 23 Nm (17 lb-ft). Install exhaust manifold/turbo with new gasket, torque nuts to 32 Nm (24 lb-ft). Reconnect exhaust downpipe.
    Torque spec

    Intake Manifold Bolts25 Nm (18 lb-ft)

    Exhaust Manifold Nuts25 Nm (18 lb-ft)
12. 12

    Reinstall electrical and fuel systems
    Install new spark plugs torqued to specification. Install ignition coils. Reconnect all electrical connectors to injectors, sensors, and actuators using labels from disassembly. Install fuel rail and reconnect fuel line quick-connects. Verify all connectors are fully seated and locked. Reconnect all vacuum lines, PCV, and breather hoses. Install air intake system and intercooler piping.
13. 13

    Refill fluids and complete reassembly
    Install new oil filter and refill engine with 4 quarts Honda 0W-20 oil. Refill cooling system with 6 quarts Honda Type 2 blue coolant using radiator and reservoir fill points. Bleed cooling system by running engine with heater on full until thermostat opens and cooling fan cycles. Reinstall engine splash shield and wheels. Reconnect battery negative cable. Install engine cover.

Reassembly

1. Torque all fasteners to specification in proper sequence - this is critical for head gasket sealing
2. Timing chain alignment must be verified by rotating engine at least 2 full revolutions and confirming TDC marks realign
3. Ensure all electrical connectors are fully seated and locked - verify with light tug on each connector
4. Cooling system must be properly bled to prevent air pockets which can cause overheating

Verification

• Start engine and verify no coolant or oil leaks at head gasket, valve cover, or intake/exhaust manifolds
• Allow engine to reach full operating temperature and verify cooling fan cycles normally
• Check for proper idle quality and smooth acceleration with no misfires or rough running
• Verify no abnormal noises from valve train or timing chain area
• Monitor coolant level over first 100 miles and top off as needed after system fully burps air
• Check engine oil level and condition after initial warm-up cycle
• Perform compression test if available - all cylinders should be within 10% of each other and meet specification
• Scan for diagnostic trouble codes and verify no emissions or timing-related faults are present

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