Short Block Replacement

This procedure covers the removal and replacement of the short block assembly on a 2007 Ram 3500 with the 5.9L Cummins diesel engine, including disassembly of cylinder head, oil pan, oil pump, crankshaft, and pistons.

Warnings

Tools required

Parts

• Short block assembly (remanufactured or new) × 1 — Use OEM specification
• Main bearing set × 1 — STD or appropriate oversize
• Rod bearing set × 1 — STD or appropriate oversize
• Piston ring sets × 1 — 6 cylinder set
• Cylinder head gasket set × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Front crankshaft seal × 1 — Use OEM specification
• Rear main seal × 1 — Use OEM specification
• Oil pump × 1 — Use OEM specification
• Oil pickup tube O-ring × 1 — Use OEM specification
• Connecting rod bolts × 12 — Use OEM specification
• Main cap bolts × 28 — Use OEM specification
• Cylinder head bolts × 24 — Use OEM specification
• Oil filter × 1 — Use OEM specification
• Fuel filter × 1 — Use OEM specification

Fluids

• 15W-40 diesel oil or 5W-40 synthetic — 12 qt
• HOAT coolant 50/50 — 28 qt

Preparation

1. Disconnect both batteries and remove battery trays to prevent accidental cranking
2. Drain engine oil completely and remove oil filter
3. Drain coolant from block and radiator into appropriate containers
4. Relieve fuel system pressure by loosening fuel filter bleed screw
5. Remove hood for clearance and access
6. Remove air intake system including intercooler boots and tubes
7. Remove radiator, fan shroud, and cooling fan assembly
8. Disconnect all fuel lines from injection pump and return lines
9. Label and disconnect all electrical connectors from engine sensors, starter, and alternator
10. Remove exhaust manifold and turbocharger as an assembly
11. Remove alternator, power steering pump, and A/C compressor (hang compressor without disconnecting lines)
12. Support transmission with jack and remove bellhousing bolts
13. Attach engine hoist with load leveler to engine lifting brackets
14. Prepare clean workspace with engine stand ready for block disassembly

Procedure

1. 1

   Remove cylinder head assembly
   Remove valve cover. Loosen cylinder head bolts in reverse of tightening sequence (outside to inside pattern). The 5.9L Cummins ISB uses 26 head bolts. Mark each bolt for position. Lift cylinder head straight up to avoid damaging deck surface. Place cylinder head on clean surface with valves facing up. Remove and retain pushrods in order.
2. 2

   Remove oil pan and pickup tube
   Remove oil pan mounting bolts working from outside to inside. Carefully separate oil pan from block using plastic scraper - do not pry on sealing surfaces. Remove oil pickup tube mounting bolts and extract pickup tube with O-ring. Inspect for debris or metal contamination which indicates bearing failure.
3. 3

   Remove oil pump and front cover
   Remove oil pump mounting bolts and extract oil pump assembly. Remove front timing cover bolts and separate cover from block. Note position of any dowel pins. Remove crankshaft front seal from timing cover. Inspect gear train for wear or damage.
4. 4

   Remove pistons and connecting rod assemblies
   Rotate crankshaft to position each piston at bottom dead center. Use ridge reamer to remove any ridge at top of cylinder bore to prevent ring damage during removal. Mark each connecting rod cap and rod with cylinder number and orientation using number stamps. Remove connecting rod cap bolts. Tap caps lightly with rubber mallet to separate. Push piston and rod assembly out through top of block. Install rod caps back on rods immediately to prevent mixing. Repeat for all six cylinders.
5. 5

   Remove crankshaft and main bearing caps
   Mark each main bearing cap with position number (1-7 from front to rear) and directional arrow pointing toward front of engine. The Cummins uses a seven main bearing design with two-bolt main caps. Remove main cap bolts in stages, loosening each cap evenly. Once all bolts are removed, tap caps with rubber mallet to break free. Use main cap puller if necessary - never pry on caps. Carefully lift crankshaft straight up out of block using assistance due to weight (approximately 120 lbs). Place on protected surface.
6. 6

   Inspect and prepare block
   Thoroughly clean block deck surface, main bearing bores, and cylinder bores using solvent and clean rags. Inspect cylinder bores for scoring, out-of-round, or taper using dial bore gauge. Measure at top, middle, and bottom at 90-degree intervals. Acceptable bore taper is less than 0.002 inches. Check block deck for warpage using precision straightedge and feeler gauges. Clean all oil passages with rifle brush and compressed air. Inspect main bearing saddles for damage or scoring. If cylinders require honing or oversized pistons, this must be performed by machine shop before reassembly.
7. 7

   Install main bearings and crankshaft
   Install upper main bearing shells into block saddles, ensuring oil holes align with block passages. Apply thin coat of assembly lube to bearing surfaces. Carefully lower crankshaft into block, ensuring thrust bearing is properly positioned at its correct main journal per the service manual (rear main on 5.9L Cummins). Install lower bearing shells into main caps with assembly lube. Install main caps in correct position and orientation - arrows must point forward. Install new main cap bolts finger-tight in proper sequence. Torque main cap bolts per factory service manual specification in multiple stages following prescribed pattern (typically inside-out, front to rear). Use angle gauge for torque-to-yield final tightening. Verify crankshaft rotates freely with no binding. Check crankshaft endplay using dial indicator (specification typically 0.0047-0.0134 inches).
8. 8

   Prepare and install piston assemblies
   If reusing pistons, thoroughly clean piston ring grooves and oil drain holes. Install new piston rings with ring gaps staggered 120 degrees apart per manufacturer instructions. Top compression ring typically has dot or marking facing up. Install oil control ring first, then lower and upper compression rings. Lubricate cylinder walls with clean engine oil. Install new connecting rod bearings in rods and caps with assembly lube. Lubricate piston skirts and rings. Compress rings using piston ring compressor. Position piston with valve reliefs or markings oriented correctly (typically toward front of engine). Tap piston into cylinder bore using wooden hammer handle, ensuring rings enter bore squarely.
9. 9

   Install connecting rods to crankshaft
   Rotate crankshaft to position journal at bottom dead center for each cylinder. Guide connecting rod onto crankshaft journal ensuring rod orientation is correct. Install bearing cap in correct position matching marks made during disassembly. Install new connecting rod bolts and tighten finger-tight. Torque rod bolts per factory specification in multiple stages (typically 30-40 ft-lbs initial, then angle torque 60-90 degrees). Verify rod side clearance using feeler gauge between rod and crankshaft journal (specification typically 0.005-0.020 inches). Verify rod can swing freely on journal. Repeat for all six cylinders.
10. 10

    Install oil pump and timing components
    Install new front crankshaft seal into timing cover using seal driver, ensuring seal is flush and square. Apply sealant to timing cover mounting surface per factory specification. Install timing cover with new gasket, ensuring alignment dowels seat properly. Install oil pump assembly with new gasket, ensuring pump drive gear properly engages crankshaft or camshaft gear. Prime oil pump by packing with petroleum jelly. Torque oil pump mounting bolts per specification. Rotate crankshaft to verify smooth rotation of pump.
11. 11

    Install oil pickup and oil pan
    Install new O-ring on oil pickup tube. Install pickup tube into block and torque mounting bolts to specification. Verify pickup is positioned correctly with proper clearance to pan bottom (typically 1/4 to 3/8 inch). Thoroughly clean oil pan and mating surface. Apply RTV sealant at block-to-timing cover joints and rear main seal housing corners. Install oil pan gasket or apply continuous bead of RTV per factory specification. Install oil pan and torque bolts in crisscross pattern from center outward per specification. Allow RTV to cure per manufacturer instructions before filling with oil.
12. 12

    Install rear main seal
    Clean rear main seal housing thoroughly. Install new rear main seal using seal installation tool, driving seal in squarely until flush with housing face. Some Cummins engines use two-piece seal requiring specific installation procedure. Apply small amount of RTV to seal housing corners where it meets oil pan rail. Ensure seal lip is properly oriented toward inside of engine.
13. 13

    Install cylinder head and valve train
    Verify block deck and cylinder head mating surfaces are perfectly clean with no gasket material or debris. Install new cylinder head gasket with proper orientation (check for TOP markings and ensure coolant passages align). Carefully lower cylinder head onto block, aligning with dowel pins. Install new cylinder head bolts with light oil on threads and under bolt heads. Torque head bolts following factory sequence (typically starts at center and works outward in specific pattern) using multiple stages: initial torque, intermediate torque, and final angle torque. 5.9L Cummins typically requires 3-stage torque plus angle rotation. Install pushrods in original positions. Install rocker arms and adjust valve lash per factory specification (cold setting typically 0.010 in intake and 0.020 in exhaust — verify against the service manual).
14. 14

    Reinstall external components and accessories
    Reinstall the Bosch CP3 high-pressure common-rail fuel pump (no static injection timing required — mount and torque per spec). Install alternator, power steering pump, and A/C compressor with new belts. Reconnect all electrical connectors per labeling. Install exhaust manifold with new gaskets and turbocharger assembly. Install intercooler system and air intake. Install cooling system components including water pump (if removed), thermostat housing, radiator, and fan assembly. Install new fuel filter and bleed fuel system. fan assembly. Install new fuel filter and bleed fuel system.
15. 15

    Final assembly and initial startup preparation
    Install new oil filter. Fill engine with correct quantity and grade of diesel engine oil (12 quarts for 5.9L Cummins). Fill cooling system with proper HOAT coolant mixture (28 quarts total capacity). Reconnect batteries. Before starting, prime the oil system by cranking with the fuel shut off (disable fueling via the fuel shutoff/relay) until oil pressure builds. Note: the 5.9L Cummins uses an intake grid heater, not glow plugs. Verify oil pressure gauge shows pressure within 15-20 seconds of cranking. Restore fueling once oil pressure is confirmed. Perform leak-down test or compression test to verify ring seal if equipment available. Check for any fuel, oil, or coolant leaks around all connections.

Reassembly

1. Torque all fasteners to factory specifications in proper sequence - critical for Cummins diesel engine
2. Use new gaskets and seals throughout - never reuse head gasket, main seal, or rod/main bolts
3. Prime oil system before initial start by cranking with fuel shut off or injectors removed
4. Adjust valve lash after engine reaches operating temperature and recheck after first 500 miles
5. All bearing clearances must be verified with Plastigage or micrometers before final assembly
6. Follow proper break-in procedure: avoid extended idle, vary RPM, no heavy loads for first 500 miles

Verification

• Verify engine starts within normal cranking time and runs smoothly without knocking or unusual noises
• Confirm oil pressure reaches 30-40 PSI at idle and 50-60 PSI at 2000 RPM within first minute
• Check for oil, fuel, or coolant leaks around all gasket surfaces and connections
• Monitor engine temperature to ensure proper cooling system operation and thermostat function
• Verify no blow-by smoke from crankcase breather indicating poor ring seal
• Test drive vehicle under light load and verify normal power delivery and no excessive smoke
• After initial 500-mile break-in, change oil and filter, recheck valve lash adjustment
• Monitor oil consumption and coolant level for first 1000 miles to detect any sealing issues

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