Replace valve stem seals to address oil consumption or smoking issues by removing camshafts and using a valve spring compressor while keeping valves from dropping into cylinders.

Warnings

Tools required

Parts

• Valve stem seal set (16 seals) × 1 — Use OEM specification
• Valve cover gasket × 1 — Use OEM specification
• Spark plug tube seals × 4 — Use OEM specification
• Camshaft timing chain cover gasket × 1 — Use OEM specification
• Engine oil × 1 — Toyota Genuine 0W-20
• Oil filter × 1 — Use OEM specification
• PCV valve grommet (if damaged) × 1 — Use OEM specification
• RTV gasket maker (Toyota FIPG or equivalent) × 1 — Use OEM specification

Fluids

• Toyota Genuine 0W-20 — 5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable and wait 90 seconds for airbag system discharge
3. Remove engine cover by pulling upward on perimeter clips
4. Drain engine oil completely and remove oil filter
5. Remove air intake assembly from throttle body to air filter box
6. Disconnect ignition coil connectors and remove all four ignition coils
7. Label and photograph all vacuum lines, electrical connectors, and hose routing for reassembly reference
8. Support engine from below or use engine support bar across fender openings

Procedure

1. 1

   Remove spark plugs and prepare cylinders
   Remove all four spark plugs and inspect for oil fouling which confirms valve seal failure. Keep plugs organized by cylinder for diagnostic reference. Clean any debris from spark plug tubes to prevent contamination.
2. 2

   Remove valve cover assembly
   Disconnect PCV hoses and any breather hoses from valve cover. Remove valve cover bolts in reverse of tightening sequence (outside to inside). Carefully lift valve cover straight up to avoid damaging gasket surface. Remove and discard old gasket and spark plug tube seals.
3. 3

   Position engine to TDC cylinder #1
   Rotate crankshaft clockwise using 19mm socket on crankshaft pulley bolt until timing marks on camshaft sprockets align with marks on timing chain cover and TDC mark on crankshaft pulley aligns with pointer. This ensures #1 cylinder is at top dead center compression stroke. Take reference photos of timing mark positions.
   ⚠Only rotate engine in normal direction (clockwise from front). Counter-rotation can damage timing chain tensioner.
4. 4

   Remove accessory components and timing chain cover
   Remove drive belt by releasing tensioner. Remove right engine mount to access timing chain cover bolts. Remove all timing chain cover bolts and carefully separate cover from engine block. Do not damage cover gasket surfaces. Mark timing chain position relative to camshaft sprockets with paint pen before proceeding.
5. 5

   Remove camshaft timing sprockets
   Hold each camshaft with appropriate wrench on hex portion (between lobes) to prevent rotation. Remove camshaft sprocket bolts while keeping timing chain engaged on sprockets. Carefully slide sprockets forward off camshafts while maintaining chain position. Secure timing chain with wire to prevent it from falling into timing cover area.
   ⚠️Do not allow timing chain to slip off lower crankshaft sprocket. If chain falls, complete timing procedure must be performed.
6. 6

   Remove camshafts
   Mark all camshaft bearing caps with their position and orientation (intake/exhaust, cylinder number, and directional arrow). Loosen camshaft cap bolts in reverse sequence (outward from center) in multiple passes, 1/4 turn each pass to gradually release valve spring pressure. Remove caps and carefully lift camshafts straight up. Store camshafts on clean surface where they cannot roll. Inspect cam lobes for wear.
   ⚠Camshaft caps are machined matched sets. Mixing positions or orientations will cause severe engine damage.
7. 7

   Set up air pressure retention for valve #1
   Thread air hose adapter into cylinder #1 spark plug hole. Connect shop air at 90-100 PSI to hold valve against seat. Listen for air leaks at throttle body or exhaust indicating valve not fully seated - if present, rotate crankshaft slightly to ensure piston is at TDC. Air pressure must remain connected throughout valve spring removal for that cylinder.
   ⚠️Loss of air pressure while valve springs are removed will allow valves to drop into cylinder requiring head removal.
8. 8

   Remove valve springs and keepers for cylinder #1
   Position valve spring compressor tool over first valve spring for cylinder #1. Compress spring carefully until valve keepers (collets) are free. Use magnetic tool to remove both keepers - they are small and easily lost. Release spring compressor slowly and remove spring retainer and valve spring. Set parts aside organized by valve position. Repeat for both intake and exhaust valves of cylinder #1.
9. 9

   Replace valve seals for cylinder #1
   Use seal removal tool or carefully pry old valve seal off valve guide - avoid scratching guide surface. Inspect valve guide for excessive wear or damage. Lightly oil new seal and slide onto valve seal installation tool. Position tool over valve guide and tap seal squarely into place until seated against valve guide. Do not cock seal sideways during installation. Install new seals on both valves for cylinder #1.
   ⚠Valve seals must be installed straight and fully seated. Cocked or partially seated seals will fail immediately.
10. 10

    Reinstall valve springs for cylinder #1
    Install valve spring over valve stem, followed by spring retainer. Compress spring with valve spring compressor. Using magnetic tool, carefully position valve keepers into valve stem keeper groove while spring is compressed. Slowly release compressor pressure while ensuring keepers remain properly seated in groove. Tap valve stem lightly with plastic mallet to ensure keepers are fully engaged. Remove air pressure adapter from cylinder #1.
11. 11

    Repeat seal replacement for remaining cylinders
    Rotate crankshaft to bring next cylinder to TDC (180 degrees rotation for 4-cylinder). Install air pressure adapter in that spark plug hole. Repeat steps 8-10 for each remaining cylinder in firing order sequence (1-3-4-2). Maintain air pressure for each cylinder while working on its valves. Work methodically to avoid mixing valve train components between cylinders.
12. 12

    Reinstall camshafts
    Ensure crankshaft is at TDC for cylinder #1. Apply clean engine oil to all camshaft journals and lobes. Position both camshafts into cylinder head with timing marks positioned as photographed during disassembly. Install camshaft bearing caps in exact original positions following identification marks. Hand-thread all cap bolts starting from center caps. Tighten camshaft cap bolts in sequence from center outward in three passes: first pass 5 Nm, second pass 10 Nm, final pass to specification.
    Torque spec

    Camshaft Cap Bolts14 Nm (10 lb-ft)
13. 13

    Reinstall timing sprockets and verify timing
    Position timing chain onto camshaft sprockets with paint marks aligned. Slide sprockets onto camshafts while maintaining chain engagement. Verify all timing marks align correctly (camshaft sprocket marks to cover marks, crankshaft at TDC). Install and tighten camshaft sprocket bolts while holding camshafts. Double-check all timing marks before proceeding.
    ⚠️Incorrect valve timing will cause catastrophic engine damage. Verify all marks multiple times before reinstalling timing cover.
14. 14

    Reinstall timing chain cover and accessories
    Clean all gasket surfaces thoroughly with razor blade scraper. Apply new gasket or RTV sealant per manufacturer specifications to timing chain cover. Install cover carefully to avoid disturbing gasket. Tighten cover bolts to specification. Reinstall right engine mount and accessory drive belt. Rotate engine two complete revolutions by hand and recheck timing marks to confirm correct installation.
    Torque spec

    Cover Bolts16 Nm (12 lb-ft)
15. 15

    Reinstall valve cover and final assembly
    Install new spark plug tube seals into valve cover recesses. Position new valve cover gasket onto cylinder head. Install valve cover and tighten bolts in sequence from center outward to specification. Reconnect all PCV hoses and breather hoses. Apply anti-seize to spark plug threads and install spark plugs. Install ignition coils and reconnect electrical connectors. Reinstall air intake system and engine cover.
    Torque spec

    Cover Bolts16 Nm (12 lb-ft)

    Spark Plugs - Aluminum Head20 Nm (15 lb-ft)
16. 16

    Refill engine oil and perform final checks
    Install new oil filter and tighten per manufacturer specification. Refill engine with 5.0 quarts Toyota Genuine 0W-20 engine oil. Reconnect negative battery cable. Before starting engine, verify all connectors, hoses, and fasteners are properly installed. Check that no tools remain in engine bay.

Reassembly

1. Ensure all timing marks are correctly aligned before buttoning up engine
2. All camshaft bearing caps must be in original positions with identification marks visible
3. Valve cover bolts must be tightened in proper sequence to prevent gasket leaks
4. Air intake system must be fully seated to prevent unmetered air entering engine

Verification

• Start engine and verify it runs smoothly without unusual noises, indicating correct valve train assembly and timing
• Check for oil leaks at valve cover gasket, timing chain cover, and oil filter after engine reaches operating temperature
• Monitor oil consumption over next 500 miles - should be significantly reduced compared to pre-repair
• Verify no blue smoke from exhaust during cold start or hard acceleration, confirming valve seals are functioning properly
• Check engine codes with scan tool to ensure no timing-related faults are present

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