engine

Short Block Replacement

for 2021 Honda Accord 1.5L I4 Turbo · FWD

Editorial review:Chris Hackleman — Master Technician · 20+ years · Jeff Moore — Master Lexus & Toyota Mechanic · 20+ years

Difficulty

Expert

Time

15.0 h

Tools

Steps

✓Expert-verified. Personally reviewed and approved by OLP's master technicians (Chris Hackleman & Jeff Moore — 20+ years each). Always follow the vehicle's factory service information and torque specs.

This procedure covers complete short block replacement for the 2018-2024 Honda Accord 1.5L turbo engine, including removal of the cylinder head, timing components, oil pan, and installation of a new short block assembly.

Warnings

⚠️Ensure engine is completely cool before beginning work. Coolant and oil will be extremely hot if engine was recently running.

⚠️This engine uses many TTY (torque-to-yield) bolts that must be replaced and torqued in specific sequence with angle measurements. Reusing TTY bolts can result in catastrophic engine failure.

⚠The short block must be mounted securely on an engine stand for cylinder head and timing component transfer. Improper mounting can cause injury.

⚠Maintain absolute cleanliness during assembly. Any debris entering the engine can cause immediate failure upon startup.

ℹ️This procedure assumes transferring cylinder head, timing components, and accessories from old short block to new. Verify all transferred components are in serviceable condition.

Tools required

Socket set (8mm-19mm)Essential

Torque wrench (10-200 Nm)Essential

Engine hoist with levelerEssential

Engine standEssential

Timing chain holding toolEssential

Crankshaft pulley holder toolEssential

Angle gauge for TTY boltsEssential

Oil filter wrenchEssential

Drain pans (multiple)Essential

Jack and jack standsEssential

Pry bar set

Gasket scraper (plastic)Essential

Brake cleaner and shop towelsEssential

Transmission jackEssential

Dial indicator with magnetic base

Parts

Short block assembly × 1 — Use OEM specification
Cylinder head gasket × 1 — Use OEM specification
Oil pan gasket × 1 — Use OEM specification
Timing chain cover gasket × 1 — Use OEM specification
Timing chain and guides × 1 — Use OEM specification
Main bearing cap bolts × 1 — TTY bolt set
Connecting rod bolts × 1 — TTY bolt set
Oil pump O-ring × 1 — Use OEM specification
Crankshaft front seal × 1 — Use OEM specification
Crankshaft rear seal × 1 — Use OEM specification
Oil filter × 1 — Honda part 15400-RTA-003
Oil drain plug crush washer × 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
Water pump O-ring × 1 — Use OEM specification

Fluids

Honda Genuine 0W-20 — 4 qt
Honda Type 2 Coolant (Blue) — 6 qt

Preparation

Disconnect negative battery terminal and wait 3 minutes for airbag system to discharge
Raise vehicle on lift or secure on jack stands rated for vehicle weight
Remove engine cover and intake air duct assembly
Drain engine coolant completely into appropriate container
Drain engine oil and remove oil filter
Remove front wheels and engine splash shields
Relieve fuel system pressure by removing fuel pump relay and cranking engine until it stalls
Mark all electrical connectors, vacuum lines, and hoses with tape for reinstallation reference
Take photos of engine bay from multiple angles for reassembly reference
Prepare clean workspace for engine disassembly with engine stand ready

Procedure

1
Remove accessory drive belt and components
Remove serpentine belt by releasing tensioner. Remove alternator, A/C compressor (do not disconnect refrigerant lines, support aside), and power steering pump if equipped. Label all electrical connections.
2
Disconnect engine electrical and fuel connections
Disconnect all engine harness connectors including injectors, ignition coils, camshaft sensors, crankshaft position sensor, oil pressure sensor, knock sensor, and oxygen sensors. Disconnect fuel supply line using appropriate disconnect tool. Cap fuel line to prevent contamination.
3
Remove exhaust system and turbocharger connections
Disconnect exhaust downpipe from turbocharger. Remove turbocharger oil feed and return lines. Support turbocharger and exhaust manifold assembly (will be removed with cylinder head later).
4
Disconnect cooling system hoses and components
Remove radiator hoses, heater hoses, and coolant bypass hoses from engine. Disconnect thermostat housing connections. Remove coolant temperature sensors noting locations.
5
Separate transmission from engine
Support transmission with transmission jack. Remove starter motor. Remove all transmission-to-engine mounting bolts. Carefully separate transmission from engine, ensuring torque converter remains with transmission on automatic models. Support transmission securely.
Torque spec
Transmission-to-Engine Bolts55 Nm (41 lb-ft)
6
Remove engine mounts and extract engine
Attach engine hoist to factory lifting points on cylinder head. Support engine weight. Remove right side engine mount, front engine mount, and rear mount torque rod. Carefully lift engine from vehicle, tilting as necessary to clear body. Transfer engine to engine stand and secure through bell housing bolt holes.
Torque spec
Mounting Bolts45 Nm (33 lb-ft)
7
Remove timing chain cover and components
Remove crankshaft pulley using holder tool and breaker bar. Remove timing chain cover bolts in reverse of tightening sequence. Remove timing chain cover, noting position of all bolts (different lengths). Remove timing chain tensioner, guides, and timing chain. Mark camshaft and crankshaft timing positions before removal.
⚠Crankshaft pulley bolt is extremely tight (133 lb-ft). Use proper holder tool to prevent crankshaft rotation.
Torque spec
Crankshaft Pulley Bolt180 Nm (133 lb-ft)
Cover Bolts15 Nm (11 lb-ft)
8
Remove cylinder head assembly
Remove valve cover. Remove cylinder head bolts in reverse of tightening sequence (consult factory service manual for exact pattern, typically outside-to-inside). Carefully lift cylinder head with exhaust manifold and turbocharger attached. Place on clean padded surface. Do not place cylinder head gasket surface down. Inspect cylinder head for damage or warping.
9
Remove oil pan and oil pickup
Remove oil pan bolts and carefully separate oil pan from block using plastic scraper. Remove oil pickup tube mounting bolts and extract pickup. Inspect oil pickup screen for debris.
Torque spec
Oil Pan Bolts12 Nm (9 lb-ft)
10
Remove oil pump and rear main seal housing
Remove oil pump mounting bolts and carefully extract oil pump from front of block. Remove rear main seal housing/flywheel mounting surface. Keep all components organized for potential reuse or transfer to new short block.
Torque spec
Oil Pump Bolts12 Nm (9 lb-ft)
11
Prepare new short block for assembly
Mount new short block on engine stand. Verify crankshaft rotates freely by hand. Check all main bearing cap bolts are torqued to specification (these should come pre-torqued from factory but verify). Inspect all machined surfaces for damage or debris. Clean all gasket surfaces with brake cleaner.
⚠New short block may have protective oil coating. Do not remove this coating from cylinder bores or bearing surfaces until immediately before assembly.
Torque spec
Main Bearing Cap Bolts75 Nm (55 lb-ft)
12
Install oil pump and rear seal housing
Install new crankshaft rear seal in housing. Lubricate seal lip with clean engine oil. Install rear seal housing with new gasket, ensuring proper alignment. Install oil pump with new O-ring, lubricating O-ring with clean engine oil. Prime oil pump by filling with clean engine oil and rotating by hand.
Torque spec
Oil Pump Bolts12 Nm (9 lb-ft)
13
Install oil pickup and oil pan
Install oil pickup tube with new O-ring. Apply thin bead of Honda Bond HT sealant to oil pan gasket surfaces following factory pattern (3mm bead on block, allow 5 minutes to set). Install oil pan and torque bolts in crisscross pattern from center outward. Wait 30 minutes before adding oil.
ℹ️Use only Honda Bond HT or equivalent specified sealant. Excessive sealant can break loose and block oil passages.
Torque spec
Oil Pan Bolts12 Nm (9 lb-ft)
14
Install timing components
Install new crankshaft front seal, lubricating lip with clean oil. Install timing chain guides. Position crankshaft at TDC mark. Install timing chain ensuring proper alignment with crankshaft sprocket. Install timing chain tensioner in collapsed position. Apply thin bead of sealant to timing cover mating surfaces. Install timing cover with new gasket, torquing bolts in specified sequence. Install crankshaft pulley with new bolt if TTY specification requires.
⚠Timing chain must be installed with marks aligned exactly. Incorrect timing will cause severe engine damage on startup.
Torque spec
Cover Bolts15 Nm (11 lb-ft)
Crankshaft Pulley Bolt180 Nm (133 lb-ft)
15
Install cylinder head assembly
Clean cylinder head and block mating surfaces thoroughly with plastic scraper and brake cleaner. Install new cylinder head gasket in correct orientation (verify UP mark and front orientation). Carefully lower cylinder head onto block. Install new cylinder head bolts and torque in factory sequence: first to 30 Nm, then angle-tighten per factory specification (typically 90 degrees additional in multiple stages). Do not reuse old head bolts.
⚠️Cylinder head bolts are TTY and must be replaced. Follow exact torque sequence and angle specifications. Improper torquing will cause head gasket failure.
16
Install valve cover and remaining components
Install new valve cover gasket and torque cover bolts to specification in crisscross pattern. Reconnect all sensors removed from cylinder head. Install spark plugs and ignition coils. Verify camshaft timing alignment through inspection ports.
Torque spec
Cover Bolts15 Nm (11 lb-ft)
17
Reinstall engine in vehicle
Remove engine from stand and attach to hoist. Carefully lower engine into engine bay, aligning with transmission. Install transmission-to-engine bolts and torque to specification. Install all engine mounts and torque mounting bolts to specification. Remove hoist.
Torque spec
Transmission-to-Engine Bolts55 Nm (41 lb-ft)
Mounting Bolts45 Nm (33 lb-ft)
18
Reconnect all systems
Reconnect all cooling system hoses using new clamps where necessary. Reconnect fuel supply line. Reconnect all electrical connectors using reference photos. Install turbocharger oil lines with new gaskets. Reconnect exhaust system. Install accessory drive components (alternator, A/C compressor). Install serpentine belt. Install new oil filter and oil drain plug with new crush washer.
Torque spec
Oil Drain Plug35 Nm (26 lb-ft)
19
Fill fluids and perform initial checks
Fill engine with 4 quarts Honda Genuine 0W-20 oil. Fill cooling system with Honda Type 2 Blue coolant through radiator cap and reservoir. Double-check all connections, bolts, and hoses. Verify no tools or parts remain in engine bay. Reconnect negative battery terminal.
ℹ️Do not start engine yet. Perform final verification checks first.

Reassembly

Verify all electrical connectors are fully seated and locked
Check all fluid levels including oil and coolant
Verify serpentine belt is properly routed and tensioned
Confirm all hose clamps are tight and no coolant leaks are visible
Ensure all engine mount bolts are properly torqued

Verification

Remove all spark plugs and disable fuel system. Crank engine for 10-15 seconds to build oil pressure (verify oil pressure light extinguishes)
Reinstall spark plugs and enable fuel system. Start engine and verify it runs smoothly within first few seconds
Monitor for any oil, coolant, or fuel leaks during initial 5 minute idle period
Check for unusual noises including knocking, rattling, or timing chain noise
Verify proper operation of all accessories (alternator charging, A/C compressor engaging if activated)
Bleed cooling system by running engine to operating temperature with heater on maximum, then top off coolant
Perform test drive after engine reaches operating temperature, monitoring for proper performance, no warning lights, and no leaks
After test drive, recheck all fluid levels and torque on critical bolts after engine cools
Monitor oil consumption and check for leaks over first 500 miles of operation