Main Bearings

Complete removal and replacement of main bearing shells, requiring engine removal from vehicle and disassembly of crankshaft assembly including inspection of journals and bearing clearances.

Warnings

Tools required

Parts

• Main bearing set (upper and lower shells) × 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 cover gasket × 1 — Use OEM specification
• Rear main seal × 1 — Use OEM specification
• Oil pump pickup tube O-ring × 1 — Use OEM specification
• Engine oil filter × 1 — Use OEM specification
• Oil drain plug crush washer × 1 — Use OEM specification
• Various cover gaskets × 1 — Use OEM specification
• Engine coolant × 10 — Maserati OAT Coolant
• RTV silicone gasket maker (OEM approved) × 1 — Use OEM specification

Fluids

• Selenia Racing 10W-60 — 5.5 qt
• Maserati OAT Coolant — 10 qt

Preparation

1. Disconnect negative battery terminal and isolate cable away from battery post
2. Drain engine oil completely and remove oil filter, inspect oil for metal contamination
3. Drain engine coolant from radiator and engine block drain plugs
4. Remove engine cover and all upper intake components for access
5. Mark and disconnect all engine wiring harnesses, vacuum lines, and fuel lines
6. Disconnect exhaust system at turbocharger outlets and cat converters
7. Remove driveshaft and support transmission with transmission jack
8. Remove subframe mounting bolts and lower subframe if necessary for clearance
9. Attach engine hoist to factory lifting points and take up slack weight
10. Position vehicle on lift at comfortable working height for undercarriage access

Procedure

1. 1

   Remove engine from vehicle
   Disconnect all remaining engine connections including transmission bellhousing bolts, motor mounts, and accessory lines. Carefully lift engine from engine bay using hoist with load leveler to maintain proper angle. Place engine on heavy-duty engine stand and secure at bellhousing mounting points.
   Torque spec

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

   Mounting Bolts50 Nm (37 lb-ft)
2. 2

   Remove external engine components
   Remove turbochargers, exhaust manifolds, alternator, AC compressor, power steering pump, water pump, and all remaining accessories. Remove timing chain cover, timing chains, and valve covers to access cylinder head components. Mark all components for correct reinstallation.
   Torque spec

   Cover Bolts18 Nm (13 lb-ft)

   Sensor Bolts11 Nm (8 lb-ft)
3. 3

   Remove oil pan and oil pump assembly
   Remove all oil pan bolts in reverse of tightening sequence. Carefully separate oil pan from block using plastic wedge tools to avoid damaging sealing surfaces. Remove oil pump pickup tube and oil pump assembly. Inspect pickup tube screen for debris.
   Torque spec

   Oil Pan Bolts12 Nm (9 lb-ft)

   Oil Pump Pickup Tube12 Nm (9 lb-ft)
4. 4

   Remove flywheel and rear main seal housing
   Lock flywheel using appropriate holding tool. Remove flywheel bolts in star pattern reverse sequence. Remove flywheel and rear main seal housing to expose rear main bearing cap. Inspect flywheel for cracks or heat damage.
   ⚠Flywheel is heavy and may have sharp ring gear teeth. Handle carefully to avoid injury or dropping onto crankshaft flange.
   Torque spec

   Flywheel Bolts95 Nm (70 lb-ft)
5. 5

   Mark and remove connecting rod caps
   Rotate crankshaft to position each connecting rod at bottom dead center. Mark each rod and cap with cylinder number and orientation using permanent marker or punch marks. Remove connecting rod cap bolts and carefully remove caps. Push pistons up into bores and secure with rubber hose over rod bolts to protect crankshaft journals.
   ⚠Rod caps must be reinstalled in exact original orientation. Mismatched caps will cause immediate bearing failure.
6. 6

   Mark and remove main bearing caps
   Thoroughly clean area around main bearing caps. Mark each main cap with position number and directional arrow pointing toward front of engine. Note location of thrust bearing (typically center main). Remove main bearing cap bolts in reverse sequence starting from outer caps working toward center. Carefully lift caps straight up and place on clean work surface in order.
   ⚠️Main bearing caps are machined matched sets and are NOT interchangeable. Installing caps in wrong position will destroy engine.
   Torque spec

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

   Remove crankshaft and inspect journals
   Carefully lift crankshaft straight up from engine block. Place on padded work surface or crankshaft stand. Remove all upper bearing shells from block and lower shells from caps, keeping them organized by position. Clean all journals thoroughly with brake cleaner. Measure each main journal diameter in multiple locations (minimum 4 points) using micrometer. Check for out-of-round (should be less than 0.0005 inch), taper, and any scoring or damage. Record all measurements.
   ⚠If any journal shows wear beyond 0.001 inch taper or out-of-round, or has visible scoring, crankshaft must be reground and undersize bearings installed.
8. 8

   Inspect and measure block bearing bores
   Clean all main bearing saddles in block and caps thoroughly with brake cleaner and lint-free rags. Inspect for cracks, fretting, or damage. Using precision dial bore gauge, measure each bearing bore in block for proper diameter, out-of-round, and bore alignment. Check block deck surface for warping. All measurements must be within factory specifications before proceeding.
   ⚠Block damage or excessive bore wear may require align honing at machine shop. Do not attempt to install bearings in damaged or out-of-spec block.
9. 9

   Install new main bearing shells and measure clearance
   Wipe all bearing saddles completely dry. Install new upper bearing shells into block saddles, ensuring oil holes align and bearing tabs seat properly in notches. Install lower shells into caps with same attention to proper seating. Place strips of Plastigage on each crankshaft journal parallel to crankshaft centerline. Carefully lower crankshaft into position. Install main caps in correct order and orientation with new TTY bolts hand-tight only. Torque caps to 75 Nm in proper sequence, then remove caps without rotating crankshaft. Measure Plastigage width and compare to specifications (typical clearance 0.0008-0.0024 inch for new bearings). Record all clearances.
   ⚠️Do not rotate crankshaft with Plastigage in place or measurements will be invalid. Must remove caps straight up.
   ⚠Bearing clearance must be within specification for each journal. Excessive clearance causes low oil pressure and bearing failure. Insufficient clearance causes bearing seizure.
   Torque spec

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

    Final main bearing assembly
    Remove crankshaft and thoroughly clean off all Plastigage residue. Apply thin coat of assembly lube to all bearing surfaces (upper and lower shells). Install upper bearings in block and carefully lower crankshaft into position. Apply assembly lube to lower bearing shells and install them in caps. Verify thrust bearing is properly positioned in center location. Install main caps in correct sequence and orientation with new TTY bolts. Hand tighten all bolts first, then torque in proper sequence to 75 Nm. Apply additional angle torque as specified in service manual (typically 60-90 degrees additional rotation). Verify crankshaft rotates freely by hand with no binding or tight spots.
    ⚠️TTY bolts must be replaced and angle-torqued per exact service manual specification. Incorrect torque will cause bolt failure and catastrophic engine damage.
    ⚠After final torque, check crankshaft endplay using dial indicator (typical spec 0.003-0.010 inch). Improper endplay indicates thrust bearing installation error.
    Torque spec

    Main Bearing Cap Bolts75 Nm (55 lb-ft)
11. 11

    Install connecting rod bearings and reinstall pistons
    Clean connecting rod bearing surfaces thoroughly. Install new rod bearings (if replacing during this service) with proper assembly lube. Remove rubber hose protectors from rod bolts. Rotate crankshaft to position each rod journal at bottom dead center and carefully guide each piston assembly down into contact with journal. Install rod caps in correct orientation with proper torque specifications. Verify crankshaft still rotates freely after each rod is installed.
    ℹ️While main bearings are primary focus, inspect rod bearings for wear. If main bearings failed, rod bearings likely also need replacement.
12. 12

    Install oil pump, pickup tube, and oil pan
    Install new O-ring on oil pump pickup tube. Position pickup tube and torque mounting to specification. Install oil pump with new gasket. Clean oil pan and block sealing surfaces completely, removing all old gasket material. Apply thin bead of OEM-approved RTV to oil pan corners where block meets main caps. Install new oil pan gasket and position oil pan. Install oil pan bolts and torque in proper sequence from center outward to specification.
    Torque spec

    Oil Pump Pickup Tube12 Nm (9 lb-ft)

    Oil Pan Bolts12 Nm (9 lb-ft)
13. 13

    Install rear main seal, flywheel, and external components
    Install new rear main seal housing with proper sealant application. Install flywheel with new bolts if specified, torquing in star pattern to specification. Reinstall timing chains, timing cover with new gasket, valve covers, and all external accessories in reverse order of removal. Apply new gaskets and proper torque specifications to all components.
    Torque spec

    Flywheel Bolts95 Nm (70 lb-ft)

    Cover Bolts18 Nm (13 lb-ft)

    Gasket Bolts21 Nm (16 lb-ft)
14. 14

    Reinstall engine and connect all systems
    Using engine hoist, carefully lower engine into vehicle and mate to transmission. Install all transmission-to-engine bolts and torque to specification. Reconnect motor mounts and torque mounting bolts. Reconnect all wiring harnesses, fuel lines, vacuum lines, exhaust system, driveshaft, and cooling system hoses. Reinstall subframe if removed. Install new oil filter and fill with specified Selenia Racing 10W-60 oil (5.5 quarts). Install drain plug with new crush washer torqued to specification.
    Torque spec

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

    Mounting Bolts50 Nm (37 lb-ft)

    Oil Drain Plug35 Nm (26 lb-ft)
15. 15

    Fill fluids and perform initial startup
    Fill cooling system with Maserati OAT coolant (10 quarts) and bleed air from system. Reconnect battery. Remove spark plugs or disable fuel/ignition and crank engine for 15-20 seconds to prime oil system and build oil pressure. Reinstall spark plugs or restore fuel/ignition. Start engine and verify immediate oil pressure on gauge. Listen carefully for any unusual noises. Allow engine to reach operating temperature while monitoring for leaks, proper oil pressure, and cooling system function. Perform idle relearn procedures if required.
    ⚠️If oil pressure does not register immediately on startup, shut down engine immediately. Lack of oil pressure will destroy new bearings in seconds.
    ⚠Monitor engine carefully during first 20 minutes of operation. Any knocking, low oil pressure, or coolant leaks require immediate shutdown and investigation.

Reassembly

1. All bearing clearances must be verified and documented before final assembly
2. All torque-to-yield fasteners must be replaced with new parts
3. Follow exact torque sequences specified in factory service manual for main caps and oil pan
4. Use only OEM-approved gaskets, seals, and sealants throughout assembly
5. Prime oil system before initial startup to ensure immediate oil pressure

Verification

• Verify oil pressure reaches minimum 25 PSI within 2 seconds of startup and maintains proper pressure at idle and under load
• Check for any oil leaks from oil pan, timing cover, rear main seal, and all gasket surfaces
• Listen for any abnormal engine noises including knocking, ticking, or bearing rumble
• Verify coolant system holds pressure and no leaks are present after reaching operating temperature
• Monitor engine temperature to ensure proper cooling system operation
• Test drive vehicle and verify normal engine performance with no warning lights
• Recheck oil level after test drive and top off if necessary; inspect for metal contamination in fresh oil

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