This procedure involves removing the engine from the vehicle, disassembling the lower end, and replacing the connecting rod bearings on the 2.5L I4 engine.

Warnings

Tools required

Parts

• Connecting rod bearing set (standard or oversized as measured) × 1 — Use OEM specification
• Connecting rod bolts (torque-to-yield, must replace) × 8 — Use OEM specification
• Engine oil filter × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Timing cover gasket × 1 — Use OEM specification
• Front crankshaft seal × 1 — Use OEM specification
• Valve cover gasket × 1 — Use OEM specification
• Exhaust manifold gasket × 1 — Use OEM specification
• Intake manifold gasket × 1 — Use OEM specification
• Engine coolant × 1 — Toyota Super Long Life Coolant (Pink)
• RTV silicone sealant (Toyota approved) × 1 — Use OEM specification

Fluids

• Toyota Genuine 0W-20 Engine Oil — 5 qt
• Toyota Super Long Life Coolant (Pink) — 10 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. Drain engine coolant into suitable container by opening radiator drain and removing radiator cap
4. Drain engine oil completely and remove oil filter
5. Remove engine cover and front splash shields
6. Relieve fuel system pressure by removing fuel pump fuse and running engine until it stalls
7. Remove hood and front bumper cover for access
8. Label and photograph all electrical connectors, vacuum lines, and hose connections before disconnection
9. Support vehicle on jack stands at manufacturer-specified lift points
10. Place engine hoist in position and attach lifting chains to engine lift points

Procedure

1. 1

   Remove Engine from Vehicle
   Disconnect all electrical connectors, fuel lines, coolant hoses, and exhaust connections from engine. Remove drive belt, A/C compressor (leave lines attached and secure aside), alternator, and power steering pump mount if applicable. Disconnect transmission from engine by removing bellhousing bolts. Remove engine mount bolts and carefully lift engine out of vehicle using hoist. Transfer engine to engine stand and secure properly.
2. 2

   Remove External Engine Components
   With engine on stand, remove intake manifold, exhaust manifold, valve cover, timing chain cover, and all accessories still attached. Remove timing chain, tensioner, and guides following proper timing chain removal procedure. Remove oil pump and pickup tube. Keep all hardware organized by component for reassembly.
3. 3

   Remove Oil Pan and Windage Tray
   Remove oil pan bolts in reverse order of tightening sequence (consult service manual for pattern). Carefully separate oil pan from block using plastic wedges if needed. Remove windage tray or baffle if equipped. Clean all gasket surfaces thoroughly with plastic scraper and solvent. Inspect oil pan for cracks or damage.
4. 4

   Inspect and Mark Connecting Rods
   Rotate crankshaft to bring cylinder 1 to bottom dead center. Using permanent marker or stamping tool, mark each connecting rod cap and rod body with cylinder number (1-4) and orientation arrow pointing toward front of engine. Verify factory markings are visible. Take photos for reference. Check for any existing damage or scoring on rod journals.
   ⚠Connecting rod caps are NOT interchangeable between cylinders or reversible. Improper installation will cause immediate engine failure.
5. 5

   Remove Connecting Rod Caps
   Starting with cylinder 1, remove the two connecting rod bolts completely. Carefully tap cap with plastic mallet if needed to break loose. Remove cap and lower bearing shell, keeping them together and organized. Repeat for remaining cylinders. Push each piston/rod assembly up into cylinder bore slightly to access upper bearing. Remove upper bearing shells from each rod. Inspect all bearing surfaces for wear, scoring, or discoloration.
   ℹ️Do not allow connecting rods to contact crankshaft journals during removal. Cover journals with shop towels for protection.
6. 6

   Measure Crankshaft Journal Dimensions
   Using micrometer, measure each rod journal diameter in multiple locations (front-to-back and side-to-side) to check for taper and out-of-round conditions. Record all measurements. Standard journal diameter for 2.5L A25A-FKS engine is approximately 48mm (consult service manual for exact spec and tolerance). Journals must be within 0.01mm roundness tolerance. If out of spec, crankshaft requires grinding and oversized bearings.
   ⚠Journals with scoring, heat discoloration, or out-of-spec dimensions require crankshaft machining or replacement.
7. 7

   Clean All Components Thoroughly
   Clean crankshaft journals with lint-free cloth and solvent. Clean connecting rod bearing surfaces, removing all old oil and debris. Blow out oil passages in crankshaft and connecting rods with compressed air. Ensure all surfaces are perfectly clean and dry before installing new bearings. Inspect rod big end bores for damage or out-of-round condition.
   ℹ️Any debris or contamination on bearing surfaces will cause premature bearing failure.
8. 8

   Install New Upper Bearing Shells
   Wipe new upper bearing shells with clean lint-free cloth. Install upper bearing shells into connecting rods, ensuring bearing tang engages slot in rod properly. Do NOT apply oil yet. Bearings should snap into place and sit flush. Install one bearing at a time, keeping components organized by cylinder number.
   ℹ️Bearing shells have a tang that must align with the notch in the connecting rod. Improper seating will cause bearing failure.
9. 9

   Check Bearing Clearance with Plastigage
   Place strip of Plastigage lengthwise across crankshaft journal for cylinder 1. Install lower bearing shell into cap (dry, no oil). Install cap onto rod in correct orientation with NEW connecting rod bolts. Torque bolts to 25 Nm (18 lb-ft) only, do NOT apply the additional 90° yet. Remove cap carefully without rotating. Measure crushed Plastigage width using scale on Plastigage envelope. Clearance should be 0.020-0.040mm. Record measurement. Repeat for all cylinders.
   ⚠Do not rotate crankshaft with Plastigage installed. This will give false readings.
   ⚠If clearance is out of specification, determine if standard or oversized bearings are needed based on journal measurements.
   Torque spec

   Connecting Rod Bolts45 Nm (33 lb-ft) + 90°
10. 10

    Final Bearing Installation
    Remove all Plastigage residue with clean cloth. Apply thin coat of clean engine assembly lube or 0W-20 oil to all bearing surfaces and crankshaft journals. Install upper bearings into rods and carefully lower each piston/rod assembly onto its journal. Install oiled lower bearing shells into caps. Install caps in correct orientation matching marks made earlier.
    ℹ️Ensure connecting rod orientation is correct with marks facing out and cylinder numbers matching.
11. 11

    Torque Connecting Rod Bolts
    Install NEW connecting rod bolts finger tight. Using torque wrench, tighten bolts to 25 Nm (18 lb-ft) in alternating pattern. Then using angle gauge, tighten each bolt an additional 90 degrees in the same alternating pattern. Verify final torque by checking that bolts do not turn when 25 Nm is reapplied. Repeat procedure for all four cylinders. Rotate crankshaft two full revolutions by hand to verify smooth rotation without binding.
    ⚠️Connecting rod bolts are torque-to-yield type and must be NEW. Never reuse old bolts.
    ⚠If crankshaft binds or shows excessive resistance during rotation, disassemble immediately and check for incorrect bearing installation or debris.
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft) + 90°
12. 12

    Install Oil Pan and Windage Tray
    Install windage tray if equipped. Apply thin bead of Toyota RTV sealant to oil pan gasket surfaces per service manual pattern. Install new oil pan gasket. Position oil pan and install bolts finger tight. Tighten oil pan bolts to specification in proper sequence (typically starting at center and working outward in criss-cross pattern). Allow RTV to cure per manufacturer instructions before adding oil.
    Torque spec

    Gasket Bolts20 Nm (15 lb-ft)
13. 13

    Reinstall Timing Components
    Reinstall oil pump and pickup tube. Install timing chain, guides, and tensioner following proper timing alignment procedure for 2.5L engine. Install timing chain cover with new gasket and front crankshaft seal. Install valve cover with new gasket. Reinstall all external engine components including intake manifold, exhaust manifold, and accessories.
    Torque spec

    Cover Bolts16 Nm (12 lb-ft)

    Gasket Bolts20 Nm (15 lb-ft)

    Mounting Bolts27 Nm (20 lb-ft)

    Sensor Bolts11 Nm (8 lb-ft)
14. 14

    Reinstall Engine in Vehicle
    Using engine hoist, carefully lower engine back into engine bay. Align engine with transmission and install bellhousing bolts. Install engine mount bolts and torque to specification. Reconnect all electrical connectors, fuel lines, coolant hoses, and exhaust connections per photos and labels. Reinstall A/C compressor, alternator, and drive belt. Install new oil filter.
    Torque spec

    Mounting Bolts27 Nm (20 lb-ft)
15. 15

    Fill Fluids and Initial Start
    Fill crankcase with 5.0 quarts of Toyota Genuine 0W-20 engine oil. Fill cooling system with 10.0 quarts of Toyota Super Long Life Coolant (Pink). Reconnect battery. Prime oil system by cranking engine for 5 seconds without starting (disable ignition or fuel). Check for oil pressure indication. Start engine and verify oil pressure immediately. Allow engine to idle and check for leaks. Monitor oil pressure, coolant temperature, and listen for abnormal noises. Bleed cooling system per manufacturer procedure.
    ⚠️If oil pressure warning light does not extinguish within 5 seconds of starting, shut down immediately and investigate.
    ⚠Do not rev engine for first 30 minutes of operation. Allow bearings to seat properly.

Reassembly

1. Torque all fasteners to specification using proper sequence patterns
2. Replace all gaskets, seals, and torque-to-yield bolts with new parts
3. Double-check all electrical connectors and hose connections are secure
4. Verify timing chain alignment before final assembly
5. Allow RTV sealant to cure fully before starting engine

Verification

• Verify oil pressure registers normally within 5 seconds of engine start
• Check for oil, coolant, and fuel leaks after initial start and 10-minute warm-up
• Listen for abnormal engine noises including knocking or ticking that would indicate bearing issues
• Allow engine to reach operating temperature and verify cooling system operation
• Perform test drive and monitor oil pressure, temperature, and engine performance
• Recheck oil level after engine cools and top off if necessary
• Inspect for leaks again after 50-100 miles of operation and retorque oil pan if needed

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