This procedure covers the removal and replacement of a single piston in the 2.5L I4 engine, requiring engine disassembly including cylinder head removal to access the piston and connecting rod assembly.

Warnings

Tools required

Parts

• Piston assembly with rings and wrist pin × 1 — Use OEM specification for 2.5L Smartstream
• Connecting rod bearing set (upper and lower) × 1 — Use OEM specification, measure for size
• Cylinder head gasket × 1 — Use OEM MLS gasket
• Connecting rod bolts × 2 — Replace TTY bolts - OEM required
• Oil pan gasket × 1 — Use OEM specification
• Valve cover gasket × 1 — Use OEM specification
• Timing chain cover gasket × 1 — Use OEM specification
• Engine oil filter × 1 — Use OEM specification
• Oil drain plug crush washer × 1 — Aluminum 14mm
• Coolant (Hyundai Long Life Green) × 1 — Use OEM specification
• RTV silicone gasket maker × 1 — OEM approved anaerobic sealant

Fluids

• Hyundai Genuine 0W-20 — 5 qt
• Hyundai/Kia Long Life Coolant (Green) — 10 qt

Preparation

1. Park vehicle on level surface and engage parking brake. Chock rear wheels.
2. Disconnect negative battery cable and isolate from battery post.
3. Remove engine cover and any upper plastic covers.
4. Drain engine coolant completely into appropriate container and mark for disposal or reuse if clean.
5. Drain engine oil and remove oil filter. Inspect drained oil for metal particles indicating additional damage.
6. Remove front bumper cover for access to radiator and cooling system components.
7. Remove radiator, condenser, and cooling fans as an assembly.
8. Remove air intake system including air box, intake tube, and throttle body.
9. Disconnect all electrical connectors, vacuum lines, and fuel lines from engine. Label each connection.
10. Remove exhaust manifold and downpipe.
11. Support engine with hoist from above using appropriate lifting brackets.
12. Remove engine mount bolts and slightly raise engine for clearance during disassembly.
13. Set up clean workspace with organized parts storage to maintain component orientation.

Procedure

1. 1

   Remove valve cover and accessory components
   Remove ignition coils and spark plugs, labeling their cylinder positions. Remove the valve cover by loosening bolts in reverse of tightening sequence. Disconnect PCV system and any remaining hoses attached to valve cover. Inspect valve train for any damage or unusual wear patterns that might indicate why piston replacement is needed.
2. 2

   Remove timing chain components
   Rotate engine to TDC on cylinder #1 (align timing marks). Remove timing chain cover after removing all mounting bolts. Mark timing chain orientation to camshaft and crankshaft sprockets using paint marker. Remove timing chain tensioner, then carefully remove timing chain. Keep all timing components organized and protected from dirt.
   ⚠Do not rotate crankshaft or camshafts once timing chain is removed or valve-to-piston contact may occur.
   Torque spec

   Cover Bolts16 Nm (12 lb-ft)
3. 3

   Remove cylinder head assembly
   Remove cylinder head bolts in reverse of tightening sequence (outside to inside pattern). Carefully lift cylinder head straight up to avoid damaging deck surface. Place cylinder head on padded wooden blocks, camshaft side up. Cover exposed head to prevent debris contamination. Remove and discard head gasket. Inspect head surface and block deck for damage, warping, or debris.
   ⚠Cylinder head is heavy (approximately 50 lbs). Use proper lifting technique or get assistance.
   Torque spec

   Cylinder Head Bolts65 Nm (48 lb-ft)
4. 4

   Remove oil pan and oil pickup
   Remove oil pan mounting bolts in a crossing pattern to avoid warping the pan. Carefully separate oil pan from block using plastic gasket scraper if needed. Remove oil pickup tube and screen assembly. Inspect pan for metal debris or sludge which may indicate additional engine damage. Clean all gasket surfaces thoroughly.
   Torque spec

   Oil Pan Bolts12 Nm (9 lb-ft)
5. 5

   Identify and prepare cylinder for piston removal
   Identify which cylinder requires piston replacement. Rotate crankshaft to bring that piston to TDC. Use ridge reamer to remove any ridge at top of cylinder bore - this prevents piston ring damage during removal. Clean ridge reamer shavings completely from cylinder and crankcase. Measure cylinder bore diameter at multiple points to verify it is within specification (no machining required).
   ℹ️If cylinder bore is more than 0.002 inches out-of-round or tapered, or exceeds maximum diameter, cylinder must be bored and honed with oversized piston installed.
6. 6

   Remove connecting rod cap and piston assembly
   Mark connecting rod and cap with cylinder number and orientation if not already marked. Remove connecting rod bolts (these will be discarded). Remove connecting rod cap and lower bearing shell. Push piston and connecting rod assembly up and out through top of cylinder bore. Remove upper bearing shell from connecting rod. Cover remaining rod journals on crankshaft with protective caps or cloth to prevent damage.
   ⚠Do not allow connecting rod to contact crankshaft journal during removal as this will score the journal surface.
   Torque spec

   Connecting Rod Bolts45 Nm (33 lb-ft)
7. 7

   Inspect components and prepare new piston
   Inspect crankshaft connecting rod journal for scoring, discoloration, or out-of-round condition. Measure journal diameter with micrometer. Inspect connecting rod for twisting, bending, or damage - replace if any damage found. Clean connecting rod thoroughly. Verify new piston is correct part number and orientation. Install new piston rings on new piston using ring installation tool, ensuring ring gaps are properly spaced 120 degrees apart and not aligned with pin bore.
8. 8

   Install new connecting rod bearings and check clearance
   Install new upper bearing shell in connecting rod and lower bearing shell in rod cap, ensuring bearing tabs engage notches properly. Do NOT lubricate bearings yet. Place Plastigage across crankshaft journal. Install rod cap with bearings (dry) and torque connecting rod bolts to specification only (no angle yet). Remove cap and measure Plastigage width to verify bearing clearance is within 0.0008-0.0020 inches. If clearance is incorrect, verify parts and journal dimensions.
   ℹ️This is a trial assembly. Bolts will be removed and must be replaced with new bolts for final assembly.
   Torque spec

   Connecting Rod Bolts45 Nm (33 lb-ft)
9. 9

   Install piston and connecting rod assembly
   Remove rod cap and thoroughly clean all Plastigage residue. Lubricate cylinder bore with clean engine oil. Lubricate piston rings, piston skirt, and rod bearings with engine assembly lube or clean engine oil. Ensure piston orientation mark (arrow or F) faces timing chain side of engine. Install piston ring compressor on piston. Carefully guide connecting rod into cylinder bore and gently tap piston down into bore with wooden hammer handle, ensuring rod does not contact crankshaft. Guide rod onto crankshaft journal.
   ⚠Excessive force indicates ring compressor is not fully compressing rings or piston is misaligned. Do not force piston or bore and rings will be damaged.
10. 10

    Install connecting rod cap with new bolts
    Install lubricated lower bearing shell in rod cap. Ensure rod and cap alignment marks match and cap is oriented correctly. Install NEW connecting rod bolts (never reuse TTY bolts). Hand-tighten bolts, then torque to 45 Nm (33 lb-ft). Using torque angle gauge, rotate each bolt an additional 90 degrees in sequence. Verify connecting rod can move side-to-side on crankshaft journal with 0.004-0.012 inch clearance. Rotate crankshaft two full revolutions to verify smooth rotation with no binding.
    ⚠️New TTY bolts are REQUIRED. Using old bolts will result in bolt failure and catastrophic engine damage.
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
11. 11

    Clean and install oil pan
    Thoroughly clean oil pan and engine block mating surfaces with gasket scraper and brake cleaner. Ensure all old gasket material and sealant is completely removed. Apply thin bead of RTV sealant to corners where block meets timing cover. Install new oil pan gasket. Position oil pan and install bolts hand-tight. Torque oil pan bolts in a crossing pattern from center outward to specification. Allow RTV to cure per manufacturer's instructions before adding oil.
    Torque spec

    Oil Pan Bolts12 Nm (9 lb-ft)
12. 12

    Install cylinder head
    Verify block deck surface is perfectly clean and dry. Position new cylinder head gasket on block, aligning all bolt holes and coolant passages. Carefully lower cylinder head onto block, ensuring gasket does not shift. Install NEW cylinder head bolts if required per service manual (verify TTY status for your model year). Hand-tighten all bolts. Torque head bolts in proper sequence (center outward) to 65 Nm (48 lb-ft), then apply additional angle per factory specification (typically 90-120 degrees in stages). Verify specification in service manual for exact angle.
    ⚠Head bolt torque sequence and angle specifications are critical. Improper tightening will cause head gasket failure.
    Torque spec

    Cylinder Head Bolts65 Nm (48 lb-ft)
13. 13

    Reinstall timing chain and components
    Verify crankshaft and camshafts are at TDC for cylinder #1. Install timing chain onto crankshaft sprocket, then route around camshaft sprockets ensuring all timing marks align exactly as marked during disassembly. Install timing chain tensioner and release to apply tension. Install timing chain guides and install timing chain cover with new gasket. Torque cover bolts to specification. Rotate engine two complete revolutions by hand and recheck timing mark alignment.
    ⚠️Incorrect timing chain installation will cause immediate valve-to-piston contact and severe engine damage when started.
    Torque spec

    Cover Bolts16 Nm (12 lb-ft)
14. 14

    Complete engine reassembly
    Install valve cover with new gasket, torquing bolts to specification in sequence. Install spark plugs and ignition coils to correct cylinders. Reinstall all sensors, electrical connectors, vacuum lines, and fuel lines per labels. Install exhaust manifold with new gaskets. Reinstall all cooling system components including radiator assembly. Reconnect all hoses and lines. Install air intake system. Reinstall front bumper cover.
    ℹ️Double-check all electrical connectors are fully seated and all hose clamps are tight before proceeding.
15. 15

    Fill fluids and initial startup
    Install new oil filter and new drain plug crush washer. Torque drain plug to specification. Fill engine with 5 quarts of Hyundai Genuine 0W-20 oil. Fill cooling system with Hyundai/Kia Long Life Green coolant (10 quarts total capacity). Reconnect battery. Before starting, remove fuel pump fuse and crank engine for 10 seconds to build oil pressure. Reinstall fuel pump fuse. Start engine and verify oil pressure immediately. Check for any leaks around oil pan, head gasket, timing cover, and all connections. Allow engine to reach operating temperature while monitoring for leaks or abnormal noises.
    ⚠️If oil pressure light does not extinguish within 2-3 seconds or if any knocking noise is heard, immediately shut down engine and investigate.
    Torque spec

    Oil Drain Plug35 Nm (26 lb-ft)

Reassembly

1. Bleed cooling system by running engine with heater on high until thermostat opens and coolant level stabilizes
2. Check and top off all fluids including coolant overflow reservoir
3. Perform complete visual inspection under hood for any loose connections or forgotten components
4. Clear any diagnostic trouble codes that may have been set during repair
5. Reset oil life monitor if equipped

Verification

• Test drive vehicle and verify normal engine operation with no unusual noises, vibrations, or loss of power
• Monitor engine temperature gauge to verify cooling system is functioning normally
• Check for any fluid leaks after test drive, paying special attention to oil pan, valve cover, timing cover, and head gasket areas
• Verify no check engine light or warning lights are illuminated
• Recheck oil level after engine cools and top off if necessary to full mark
• Recheck coolant level after engine cools and top off if necessary
• Schedule follow-up oil and filter change at 500 miles to remove any assembly residue or break-in particles

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