Long Block Replacement

Complete replacement of the long block assembly on a 5.9L Cummins diesel engine, including removal of transmission, engine extraction, installation of new long block, and reinstallation of all components.

Warnings

Tools required

Parts

• 5.9L Cummins long block assembly × 1 — Use OEM specification
• Engine oil filter × 1 — Use OEM specification
• Fuel filter/water separator × 1 — Use OEM specification
• Complete engine gasket set × 1 — Includes head, manifold, oil pan, valve cover
• Exhaust manifold gaskets × 1 — Use OEM specification
• Turbo mounting gaskets × 1 — Use OEM specification
• Coolant hoses (upper and lower radiator) × 1 — Use OEM specification
• Heater hoses × 1 — Use OEM specification
• Engine oil × 12 — 15W-40 diesel rated
• Coolant (50/50 mix) × 28 — Ethylene glycol appropriate for year
• Serpentine belt × 1 — Use OEM specification
• Oil drain plug crush washer × 1 — Use OEM specification
• Flywheel bolts (if reusing flywheel) × 1 — TTY bolts - replace if used
• Transmission-to-engine dowel pins × 2 — Verify condition, replace if worn

Fluids

• 15W-40 diesel engine oil — 12 qt
• Ethylene glycol 50/50 coolant — 28 qt

Preparation

1. Park vehicle on level, solid surface and engage parking brake
2. Disconnect both battery cables (negative first, then positive) and remove batteries for workspace
3. Drain engine oil completely and remove oil filter
4. Drain cooling system at radiator petcock and block drains into appropriate containers
5. Remove hood completely by unbolting from hinges (requires assistant, mark hinge position)
6. Remove radiator shroud, fan clutch assembly, and radiator (disconnect transmission cooler lines if automatic)
7. Relieve fuel system pressure by loosening fuel filter drain valve
8. Label and photograph all electrical connections, vacuum lines, and fuel lines before disconnection
9. Raise and secure vehicle on jack stands at appropriate lifting points for undercarriage access
10. Remove front skid plate and belly pans for access to transmission and engine mounts

Procedure

1. 1

   Remove air intake system and accessories
   Remove complete air intake system from air filter housing to turbocharger inlet. Disconnect boost pressure tube from turbo outlet to intercooler. Remove serpentine belt and carefully remove alternator, power steering pump, and A/C compressor (if equipped). Support A/C compressor without disconnecting refrigerant lines. Remove vacuum pump from front of engine. Label all electrical connectors during removal.
2. 2

   Disconnect fuel system and injection pump
   Disconnect fuel supply and return lines at fuel filter housing using appropriate diesel line disconnect tools. Disconnect fuel lines from injection pump. Cap all open fuel lines immediately to prevent contamination. Disconnect throttle linkage and all electrical connections from injection pump. If equipped with an electronically controlled injection pump (VP44 on 1998.5-2002 models), disconnect all related wiring harnesses. Note the P7100 inline pump (1994-1998 12-valve) is fully mechanical and controlled via throttle/governor linkage. Remove injection pump drive gear cover if accessible.
3. 3

   Remove turbocharger and exhaust system
   Disconnect exhaust downpipe from turbocharger outlet. Remove oil drain tube from turbo to engine block. Disconnect oil feed line from turbo. Remove turbocharger from exhaust manifold by removing mounting nuts. Remove exhaust manifold from cylinder head. Note that studs may come out with nuts - inspect threads carefully.
   ⚠Exhaust manifold studs are prone to breaking on high-mileage engines. Apply penetrating oil 24 hours before removal if possible. Heat may be required.
   Torque spec

   Exhaust Manifold Nuts30 Nm (22 lb-ft)
4. 4

   Disconnect cooling system and heater
   Disconnect upper and lower radiator hoses from engine. Disconnect heater hoses at engine connections. Remove coolant overflow/expansion tank if it interferes with engine removal. Disconnect engine block heater power cord if equipped. Verify all coolant has been drained from engine block.
5. 5

   Disconnect electrical and control systems
   Disconnect all remaining engine electrical connectors including (as equipped for your engine year): crankshaft position sensor and camshaft position sensor (24-valve 1998.5+ only), oil pressure sender, coolant temperature sensors, grid heater relay, starter motor connections, and engine ground straps. Disconnect the throttle cable/linkage at the injection pump (12-valve P7100), or the accelerator pedal position sensor (APPS) on electronic VP44 engines. Remove engine wiring harness from engine, securing it to vehicle chassis.
6. 6

   Remove intake manifold and valve cover
   Remove intake manifold horn/plenum assembly. Disconnect any remaining vacuum lines. Remove valve cover by loosening bolts in reverse of tightening sequence (outside to inside). Inspect rocker arm assembly - this may transfer to new long block or may come with new assembly depending on long block configuration.
   Torque spec

   Intake Manifold Bolt25 Nm (18 lb-ft)

   Valve Cover Bolts10 Nm (7 lb-ft)
7. 7

   Prepare transmission for separation
   From underneath vehicle, remove transmission inspection cover. Mark flexplate/flywheel to torque converter relationship if automatic transmission. Remove torque converter bolts (automatic) by rotating engine using barring tool or large socket on crankshaft bolt. For manual transmission, remove clutch slave cylinder. Support transmission securely with transmission jack. Remove transmission crossmember.
8. 8

   Separate transmission from engine
   Remove all transmission-to-engine bellhousing bolts. Carefully separate transmission from engine by sliding straight back to disengage input shaft from clutch (manual) or torque converter (automatic). Lower transmission on jack and roll out from under vehicle. For automatic transmission, ensure torque converter stays with transmission. Verify dowel pins remain in engine block or transfer to new long block.
   Torque spec

   Transmission-to-Engine Bolts55 Nm (41 lb-ft)
9. 9

   Remove engine mounting hardware
   Remove engine mount through-bolts on both driver and passenger sides. Disconnect any remaining connections to engine. Attach engine hoist with appropriate lifting chains to factory lifting eyes on engine. Take up slack on hoist and verify engine balance with leveler tool. The 5.9L Cummins is nose-heavy; adjust chains accordingly.
   ⚠️Verify engine hoist is positioned on stable ground and rated for at least 1500 lbs. Check all chains, hooks, and lifting points before lifting.
   Torque spec

   Sensor Mounting Bolts11 Nm (8 lb-ft)
10. 10

    Extract engine from vehicle
    Slowly raise engine while guiding it forward and up out of engine bay. The engine must tilt nose-up to clear the radiator support and front crossmember. Have an assistant guide the engine and watch for any remaining connections. Once clear of vehicle, lower engine onto appropriate stand or support structure. Inspect engine bay for any components that need to be transferred or replaced.
11. 11

    Transfer components to new long block
    Transfer the following components from old engine to new long block: flywheel/flexplate (inspect for cracks and hot spots), rear main seal housing if not included, oil pan if not included, front cover and timing components if not included, injection pump and drive components, fuel system components, water pump, thermostat housing, intake and exhaust manifolds, turbocharger, all sensors and switches, oil filter adapter/housing, and any brackets. Clean all mating surfaces thoroughly. Replace all gaskets and seals during transfer. Apply anti-seize to exhaust manifold studs.
    ⚠Flywheel bolts are TTY and must be replaced. Tighten in star pattern to proper torque specification. If reusing flywheel, inspect for cracks, hot spots, and proper runout.
    Torque spec

    Flywheel Bolts95 Nm (70 lb-ft)

    Oil Pan Bolt12 Nm (9 lb-ft)

    Exhaust Manifold Nuts30 Nm (22 lb-ft)

    Intake Manifold Bolt25 Nm (18 lb-ft)
12. 12

    Install valve train components
    If rocker arm assembly was removed, install new valve cover gasket on new long block. Install rocker arm assembly, pushrods, and related components if not included with long block. Verify all components are properly lubricated with diesel engine oil before installation. Tighten valve cover bolts in sequence from center outward.
    ℹ️Some long blocks include complete valve train; verify what is included with your specific long block before disassembly.
    Torque spec

    Valve Cover Bolts10 Nm (7 lb-ft)

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

    Install new long block into vehicle
    Attach engine hoist to new long block using same lifting points. Raise engine and carefully guide into engine bay, reversing extraction procedure. Tilt engine to clear radiator support. Align engine with transmission bellhousing, ensuring dowel pins are in correct position. Lower engine onto motor mounts but do not fully tighten mount bolts yet. Verify engine sits level and aligns properly with transmission.
14. 14

    Reconnect transmission to engine
    Raise transmission on jack and align with engine bellhousing. For automatic transmission, verify torque converter is fully seated in transmission pump (should have clicked in twice). Measure torque converter seating depth and compare against the specification for your specific transmission (47RH/47RE/48RE); the converter must be fully seated into the pump before mating to prevent pump damage. Align torque converter or clutch with flywheel/flexplate. Install transmission-to-engine bolts and tighten to specification in a cross pattern. For automatic, rotate engine and install torque converter bolts, aligning marks made during disassembly. Install transmission crossmember and remove transmission jack.
    ⚠Ensure torque converter is fully engaged before mating transmission to engine. Measure converter depth - should be approximately 1/2 inch behind bellhousing face when properly seated.
    Torque spec

    Transmission-to-Engine Bolts55 Nm (41 lb-ft)
15. 15

    Install intake and exhaust systems
    Install exhaust manifold with new gaskets using anti-seize on studs/nuts. Tighten from center outward. Install turbocharger with new gaskets and connect oil feed and drain lines. Install intake manifold with new gaskets, tightening bolts in sequence from center outward. Connect all vacuum lines and boost tubes. Verify all connections are secure.
    Torque spec

    Exhaust Manifold Nuts30 Nm (22 lb-ft)

    Intake Manifold Bolt25 Nm (18 lb-ft)
16. 16

    Reconnect fuel system
    Reconnect all fuel lines to injection pump and fuel filter housing using new O-rings where applicable. Ensure all connections are tight to prevent air entry into fuel system. Reconnect throttle linkage and all injection pump electrical connections. Install new fuel filter/water separator element.
17. 17

    Reconnect cooling and electrical systems
    Install all coolant hoses with new clamps. Reconnect heater hoses. Install all electrical connectors to sensors, starter, alternator, and other components, verifying correct connections using labels/photos from disassembly. Install all ground straps securely. Install engine block heater connection if equipped.
    ⚠Verify all electrical connections are clean and properly seated. Incorrect sensor connections can cause no-start or driveability issues.
    Torque spec

    Electrical Connector Bolts7 Nm (5 lb-ft)

    Sensor Mounting Bolts11 Nm (8 lb-ft)
18. 18

    Install accessories and drive systems
    Install alternator, power steering pump, A/C compressor, and vacuum pump with all mounting bolts properly torqued. Install new serpentine belt and verify proper routing and tension. Install air intake system from air filter housing through turbocharger. Ensure all clamps are tight and no air leaks are present.
    Torque spec

    Sensor Mounting Bolts11 Nm (8 lb-ft)
19. 19

    Fill fluids and prime systems
    Install new oil filter and fill engine with 12 quarts of 15W-40 diesel engine oil. Install oil drain plug with new crush washer and torque to specification. Fill cooling system with the factory-specified capacity (approximately 22-24 quarts) of appropriate 50/50 coolant mixture; verify exact capacity for your model year. Prime the fuel system per the pump type: on 12-valve trucks use the hand primer plunger on the mechanical lift pump; on VP44 trucks operate the electric lift pump with the bleed screw loosened. Loosen the fuel filter bleed screw until bubble-free fuel flows, then retighten. Avoid extended dry cranking to prevent injection pump damage. Tighten bleed screw. Check power steering and brake fluid levels.
    ⚠Failure to properly prime fuel system will result in extended cranking and potential injection pump damage. Ensure all air is purged before extended cranking.
    Torque spec

    Oil Drain Plug35 Nm (26 lb-ft)
20. 20

    Final installation and system checks
    Tighten engine mount bolts to specification. Install radiator, fan clutch assembly, and shroud. Reconnect transmission cooler lines if equipped with automatic transmission. Install skid plates and belly pans. Reinstall batteries and connect battery cables (positive first, then negative). Install hood using marked positions. Lower vehicle from jack stands.
    Torque spec

    Sensor Mounting Bolts11 Nm (8 lb-ft)

Reassembly

1. Double-check all fluid levels before starting engine
2. Verify all electrical connections are secure and properly routed
3. Ensure no tools or parts remain in engine bay
4. Check that all hose clamps and fasteners are properly tightened
5. Verify serpentine belt routing is correct and belt tension is proper

Verification

• Perform initial start with assistant monitoring for leaks - engine should start within 10-15 seconds of cranking if properly primed
• Check for fuel, oil, and coolant leaks immediately after starting
• Verify oil pressure registers on gauge within 5 seconds of starting
• Allow engine to reach operating temperature and verify cooling system operation
• Check for exhaust leaks at manifold and turbocharger connections
• Monitor engine for unusual noises or vibrations during warm-up
• After reaching operating temperature, shut down and recheck all fluid levels
• Inspect for any fluid leaks after cool-down period
• Road test vehicle to verify proper operation under load
• Recheck all fluid levels and inspect for leaks after road test
• Check and retorque cylinder head bolts after 500 miles if required by long block manufacturer
• Perform first oil change at 500 miles to remove any break-in contaminants

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