Complete replacement of main bearings on a 2015 Kia Forte 1.8L engine, requiring engine removal, crankshaft inspection, bearing installation, and reassembly with proper torque specifications.

Warnings

Tools required

Parts

• Main bearing set (standard or oversized as measured) × 1 — Use OEM specification
• Thrust bearing set × 1 — Use OEM specification
• Main bearing cap bolts (TTY) × 10 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Timing chain cover gasket × 1 — Use OEM specification
• Rear main seal × 1 — Use OEM specification
• Oil filter × 1 — Use OEM specification
• Engine oil drain plug crush washer × 1 — Use OEM specification
• RTV silicone gasket maker × 1 — Use OEM specification
• Complete engine gasket set × 1 — Use OEM specification
• Coolant × 1 — Hyundai/Kia Long Life Coolant (Green)
• Engine oil × 1 — Kia Genuine 5W-20

Fluids

• Kia Genuine 5W-20 — 4.5 qt
• Hyundai/Kia Long Life Coolant (Green) — 7.5 qt
• Kia SP-IV-M ATF — 1 qt

Preparation

1. Park vehicle on level surface and disconnect negative battery cable
2. Drain engine coolant completely into suitable container
3. Drain engine oil and remove oil filter
4. Remove engine cover and air intake assembly
5. Relieve fuel system pressure by removing fuel pump fuse and running engine until it stalls
6. Mark and disconnect all electrical connectors, vacuum lines, and coolant hoses from engine
7. Recover refrigerant from A/C system and disconnect A/C lines
8. Remove radiator, condenser, and cooling fans
9. Raise vehicle on lift or support securely on jack stands
10. Remove front wheels and engine splash shields
11. Disconnect exhaust system at manifold flange
12. Remove drive axles and secure out of way
13. Support transmission with transmission jack
14. Remove engine mount bolts and crossmember if equipped
15. Attach engine hoist with chains to designated lifting points
16. Label all bolts and components during disassembly for proper reassembly

Procedure

1. 1

   Remove engine from vehicle
   Verify all electrical connections, hoses, and mechanical linkages are disconnected. Remove transmission-to-engine bolts. Carefully lift engine while monitoring clearance around firewall, frame rails, and A/C lines. Tilt engine as needed using load leveler. Once clear of engine bay, lower onto engine stand and secure with appropriate bolts.
   Torque spec

   Transmission-to-Engine Bolts55 Nm (41 lb-ft)
2. 2

   Remove external components and accessories
   With engine on stand, remove alternator, power steering pump, A/C compressor (if still attached), starter motor, flywheel/flexplate, and all remaining accessories. Remove valve cover, timing chain cover, and timing chain assembly. Remove cylinder head per manufacturer procedure. Remove oil pan and oil pickup tube. Remove front crankshaft seal housing if present.
   Torque spec

   Flywheel Bolts95 Nm (70 lb-ft)

   Oil Pan Bolts12 Nm (9 lb-ft)

   Oil Pump Pickup Tube12 Nm (9 lb-ft)
3. 3

   Mark and remove main bearing caps
   Verify main bearing caps are marked with numbers (1-5, front to rear) and directional arrows pointing toward front of engine. If not marked, use permanent marker to clearly mark each cap and its orientation. Loosen main bearing cap bolts in reverse of tightening sequence (consult service manual for sequence diagram). Remove bolts completely and discard (these are TTY and must be replaced). Carefully remove each bearing cap using even pressure. Keep caps in order.
   ⚠Main bearing caps must be reinstalled in exact same position and orientation. Mix-ups will cause immediate engine failure.
   Torque spec

   Main Bearing Cap Bolts75 Nm (55 lb-ft)
4. 4

   Remove crankshaft and inspect journals
   Carefully lift crankshaft straight up out of engine block. Remove upper bearing shells from block and lower shells from caps. Use micrometer to measure all five main bearing journals for out-of-round, taper, and wear. Journals must be within 0.0002 inch roundness and smoothness. Check for scoring, discoloration, or damage. Measure crankshaft endplay location (usually journal #3 with thrust bearings). If journals are worn beyond specification or damaged, crankshaft must be reground or replaced.
   ℹ️Standard journal diameter is approximately 52mm. Consult service manual for exact specifications and tolerance limits.
5. 5

   Inspect engine block bearing bores
   Clean all bearing saddles in engine block thoroughly with brake cleaner and lint-free cloth. Inspect for cracks, scoring, or damage. Use dial bore gauge to measure bearing bore diameter if available. Check block deck surface for warpage using straightedge and feeler gauges. Check main bearing cap bolt holes for thread damage. Clean oil passages with brake cleaner and compressed air, ensuring all passages are clear.
   ⚠Any cracks in main bearing saddles or webbing require engine block replacement. Do not attempt to repair.
6. 6

   Install new bearing shells and check clearance
   Select correct bearing size based on crankshaft measurements (standard or appropriate undersize). Install upper bearing shells into engine block saddles, ensuring locating tabs engage properly. DO NOT apply lubricant yet. Place strip of Plastigage across each journal parallel to crankshaft centerline. Carefully lower crankshaft into position. Install lower bearing shells into caps (dry, no lubricant). Install caps in correct position with arrows pointing forward. Install NEW main bearing cap bolts and torque to 75 Nm in proper sequence, then apply specified angle torque. Do not rotate crankshaft.
   ⚠Bearing shells must snap into place with locating tabs fully seated. Improperly seated bearings will cause failure.
   Torque spec

   Main Bearing Cap Bolts75 Nm (55 lb-ft)
7. 7

   Measure bearing clearance with Plastigage
   Remove main bearing cap bolts and carefully remove caps without rotating crankshaft. Measure width of flattened Plastigage using scale on Plastigage package. Proper clearance is 0.0008-0.0018 inch for most main bearings, with slightly looser clearance acceptable on center bearing. If clearance is too tight, inspect for debris or incorrect bearing size. If too loose, next undersize bearing is required. Record all clearances. Remove all Plastigage material completely with clean cloth.
   ⚠️All Plastigage material must be completely removed before final assembly. Any remaining material will cause immediate bearing failure.
8. 8

   Final bearing installation with lubrication
   Clean all bearing surfaces again with brake cleaner. Install upper and lower bearing shells in correct positions. Apply liberal amount of assembly lube or clean engine oil to all bearing surfaces and crankshaft journals. Pay special attention to thrust bearing surfaces. Carefully lower crankshaft into position. Install main bearing caps with arrows pointing forward, in correct numerical order (1-5, front to rear). Verify cap alignment before installing bolts.
   ℹ️Use only approved assembly lube or fresh engine oil. Do not use grease or EP lubricants on bearings.
9. 9

   Final torque main bearing caps
   Install NEW main bearing cap bolts finger tight. Following manufacturer tightening sequence (typically center journal first, then alternating front to rear), torque bolts to 75 Nm. After all bolts reach initial torque, apply additional angle torque as specified in service manual (typically 45-60 degrees additional rotation). Use angle gauge for accuracy. After torquing, check crankshaft rotation by hand - it should turn smoothly with slight resistance. Measure crankshaft endplay using dial indicator - should be 0.002-0.010 inch.
   ⚠If crankshaft does not rotate smoothly, disassemble immediately and check for debris, cap misalignment, or bearing problems.
   Torque spec

   Main Bearing Cap Bolts75 Nm (55 lb-ft)
10. 10

    Install oil pump and rear main seal
    Install new rear main seal using appropriate seal driver, ensuring it is square and seated to proper depth. Install oil pump pickup tube with new O-ring and torque fasteners to specification. Clean oil pan and engine block mating surfaces thoroughly. Apply thin bead of RTV silicone to oil pan where corners meet (if specified by manufacturer). Install oil pan with new gasket and torque bolts in proper sequence starting from center and working outward.
    Torque spec

    Oil Pan Bolts12 Nm (9 lb-ft)

    Oil Pump Pickup Tube12 Nm (9 lb-ft)
11. 11

    Reassemble engine and install timing components
    Install cylinder head with new gasket per manufacturer procedure and torque specifications. Install timing chain assembly, ensuring all timing marks align correctly per service manual. Install timing chain cover with new gasket and torque cover bolts. Install crankshaft front seal. Rotate engine by hand through two complete revolutions to verify smooth operation and correct valve timing.
    Torque spec

    Cover Bolts15 Nm (11 lb-ft)

    Gasket Bolts19 Nm (14 lb-ft)
12. 12

    Install remaining components and prepare for installation
    Install flywheel/flexplate with new bolts, torquing in star pattern to specification. Install starter motor, alternator, A/C compressor, power steering pump, and all remaining accessories. Install valve cover with new gasket. Install oil drain plug with new crush washer and torque to specification. Install new oil filter. Verify all fasteners are properly torqued and all components are secure before removing engine from stand.
    Torque spec

    Flywheel Bolts95 Nm (70 lb-ft)

    Oil Drain Plug35 Nm (26 lb-ft)

    Mounting Bolts26 Nm (19 lb-ft)

    Sensor Bolts10 Nm (8 lb-ft)
13. 13

    Install engine into vehicle
    Attach engine hoist to lifting points and remove engine from stand. Carefully lower engine into engine bay, aligning with transmission. Install transmission-to-engine bolts and torque to specification. Install engine mount bolts and torque to specification. Remove engine hoist. Reconnect drive axles, exhaust system, and all removed components. Reconnect all electrical connectors, vacuum lines, coolant hoses, and fuel lines in reverse order of removal.
    Torque spec

    Transmission-to-Engine Bolts55 Nm (41 lb-ft)

    Mounting Bolts26 Nm (19 lb-ft)
14. 14

    Fill fluids and perform initial startup
    Fill engine with correct amount and specification of engine oil (4.5 quarts Kia Genuine 5W-20). Fill cooling system with proper coolant mixture (7.5 quarts Hyundai/Kia Long Life Green coolant). Check and top off all other fluids. Reconnect negative battery cable. Prime oil system by cranking engine with fuel pump fuse removed until oil pressure registers on gauge. Reinstall fuel pump fuse. Start engine and immediately verify oil pressure. Allow engine to idle and monitor for leaks, unusual noises, or warning lights. Monitor coolant temperature and verify cooling fan operation.
    ⚠️If oil pressure does not register within 5-10 seconds of startup, shut down immediately and investigate. Running without oil pressure will destroy new bearings instantly.

Reassembly

1. Bleed cooling system completely to remove all air pockets
2. Check all fluid levels after initial warm-up and top off as needed
3. Recheck all external fasteners for proper torque after engine reaches operating temperature
4. Install engine splash shields and wheel assemblies
5. Perform complete visual inspection for leaks after 15-20 minutes of operation
6. Test drive vehicle and monitor oil pressure, temperature, and performance

Verification

• Oil pressure should read 29-57 psi at idle when warm, 43-72 psi at 3000 RPM
• Engine should run smoothly with no abnormal noises, knocking, or vibration
• No oil, coolant, or fluid leaks visible from any engine area
• Check engine oil level after shutdown and cooldown period - adjust if necessary
• Perform 500-mile break-in period with varied RPM, avoiding sustained high RPM or heavy loads
• Change engine oil and filter at 500 miles after bearing replacement to remove break-in debris
• Monitor oil pressure and engine performance for first 1000 miles - any abnormalities require immediate inspection

More procedures for this vehicle