________________________________________________________________________________

Isuzu 4BA1 Engine

The Isuzu 4BA1 is a naturally aspirated, 4-cylinder, 4-stroke, inline diesel engine belonging to the Isuzu B-series family. Produced primarily from the late 1970s through the 1990s, this engine was heavily utilized in industrial applications and light commercial vehicles, most notably the generations of the Isuzu Elf light trucks. In regions like the Philippines, it became widely popular as a highly dependable powerplant for local "jeepney" transport vehicles. Engineered with a high-durability cast-iron cylinder block and head, it is highly regarded by mechanics for its robust construction, simplicity of repair, and exceptional long-term reliability under demanding, high-load operating conditions.

The engine utilizes an Overhead Valve (OHV) valvetrain system driven via a gear-indexed camshaft. It features a total of 8 valves (2 valves per cylinder: 1 intake and 1 exhaust). Proper valve clearance adjustments are managed via mechanical rocker arm adjusters positioned under the cylinder head cover. Bore: 98 mm (3.9 inches). Stroke: 92 mm (3.62 inches). Total Displacement: 2,775 cc (2.8 Liters).

The engine utilizes a traditional mechanical direct injection (DI) fuel system. Fuel delivery is handled by an inline mechanical fuel injection pump assembly driven by the engine's timing gear train. The injection pump pressurizes and distributes fuel to individual mechanical fuel injector nozzles that spray fuel directly into the piston crowns' combustion bowls. The assembly incorporates a multi-stage primary inline fuel filter/water separator to prevent contaminants from causing internal pump or nozzle damage.

The system uses a forced-feed lubrication arrangement pressurized by a high-efficiency gear-driven oil pump. Oil is drawn up through a strainer from the steel oil pan sump and routed through a full-flow replaceable oil filter canister and integrated oil cooler system to protect internal moving components under friction. The block utilizes a liquid-forced water cooling system. It features a belt-driven centrifugal water pump that circulates coolant through the internal water jackets of the cast-iron cylinder block and head assembly. System operating temperature is regulated via a mechanical wax-pellet style thermostat and a multi-blade cooling fan attached to the water pump pulley.

General Technical Data

Engine Specifications

Engine Model ............... Isuzu 4BA1
Engine Type ............... 4-cycle inline 4-cylinder direct injection water-cooled diesel
Number of Cylinders ............... 4
Cylinder Arrangement ............... In-line vertical
Engine Bore, in (mm) ............... 3.86 (98.0)
Engine Stroke, in (mm) ............... 3.62 (92.0)
Displacement, cu.in (L) ............... 169.3 (2.775)
Rated Engine Power, hp (kW) ............... 75.0 (55.0
Rated Engine Speed, rpm ............... 4000
Peak Torque, lb-ft (Nm) ............... 122.0 (165.0) at 2200 rpm
Peak Torque Speed, rpm ............... 2200
Idle Speed, rpm ............... 700-800
Maximum No-Load Speed, rpm ............... 4300
Aspiration Type ............... Naturally Aspirated
Compression Ratio ............... 19.0:1
Firing Order ............... 1-3-4-2
Cylinder Block Material ............... Cast iron
Cylinder Head Material ............... Cast iron
Combustion Chamber Type ............... Direct injection swirl type
Piston Material ............... Aluminum alloy with strut
Crankshaft Material ............... Forged steel
Connecting Rod Material ............... Forged carbon steel
Valves per Cylinder ............... 2
Total Number of Valves ............... 8
Valvetrain Type ............... Overhead Valve (OHV)
Camshaft Location ............... In-block
Camshaft Drive Type ............... Gear-driven
Lubrication System ............... Full-pressure feed
Oil Pump Type ............... Gear-driven external type
Cooling System ............... Liquid-cooled forced circulation
Water Pump Type ............... Centrifugal belt-driven type
Thermostat Type ............... Wax pellet type
Starting System Type ............... Electric Starter
Electrical System Voltage, V ............... 12 or 24
Alternator Output, A ............... 35 or 50

Fuel System

Injection Pump Type ............... In-line Bosch A-type
Governor Type ............... Mechanical RSV type
Injection Timing, deg BTDC ............... 14.0
Injection Pressure, psi (bar) ............... 2560 (176.5)
Fuel Filter Type ............... Spin-on cartridge type
Fuel Feed Pump Type ............... Piston mechanical type
Injection Nozzle Type ............... Multi-hole type
Number of Nozzle Holes ............... 4
Nozzle Hole Diameter, in (mm) ............... 0.011 (0.28)
Fuel Tank Return Type ............... Overflow line to tank
Maximum Fuel Leak-off, qt/h (L/h) ............... 0.21 (0.20)
Fuel Transfer Pump Pressure, psi (bar) ............... 28.4-42.6 (2.0-3.0)
Fuel Injection Pipe Outer Diameter, in (mm) ............... 0.24 (6.0)
Fuel Injection Pipe Inner Diameter, in (mm) ............... 0.079 (2.0)
Minimum Fuel Tank Venting Capacity, cfm (m3/min) ............... 0.71 (0.02)
Maximum Fuel Inlet Temperature, F (C) ............... 140 (60.0)
Maximum Fuel Return Temperature, F (C) ............... 176 (80.0)
Maximum Fuel Inlet Restriction, in Hg (kPa) ............... 4.0 (13.5)
Maximum Fuel Return Restriction, in Hg (kPa) ............... 6.0 (20.3)

Dimensions and Weight

Overall Length, in (mm) ............... 31.2 (790)
Overall Width, in (mm) ............... 24.1 (610)
Overall Height, in (mm) ............... 29.5 (750)
Dry Weight, lbs (kg) ............... 518 (235)
Wet Weight, lbs (kg) ............... 550 (250)

Maintenance Data

Service Information

Compression Pressure at 200 rpm, psi (bar) ............... 441 (30.4)
Minimum Compression Pressure, psi (bar) ............... 313 (21.6)
Maximum Variance Between Cylinders, psi (bar) ............... 28.4 (2.0)
Oil Pressure at Idle Speed, psi (bar) ............... 14.2 (1.0)
Oil Pressure at Rated Speed, psi (bar) ............... 42.6-71.1 (3.0-4.9)
Thermostat Opening Temperature, F (C) ............... 170 (76.5)
Thermostat Full Open Temperature, F (C) ............... 194 (90.0)
Radiator Cap Relief Pressure, psi (bar) ............... 12.8 (0.9)
Fan Belt Deflection under 22 lbs force, in (mm) ............... 0.39-0.47 (10.0-12.0)
Intake Valve Clearance, Cold, in (mm) ............... 0.016 (0.40)
Exhaust Valve Clearance, Cold, in (mm) ............... 0.016 (0.40)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, or SAE 15W-40
API Service Classifications ......................... CD, CE, or CF-4
Engine Oil Capacity with Filter, qt (L) ............... 7.4 (7.0)
Engine Oil Capacity without Filter, qt (L) ............... 6.3 (6.0)
Cooling System Capacity, qt (L) ............... 10.6 (10.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Inspect air cleaner ............... Every 100 hours
Replace air cleaner ............... Every 500 hours
Replace fuel filter ............... Every 500 hours
Valve clearance adjustment ............... Every 500 hours
Fuel system inspection ............... Every 1000 hours
Change coolant ............... Every 2000 hours
Compression test ............... Every 1000 hours
Belt inspection ............... Every service cycle

Service Specifications

Cylinder Liner Bore Diameter, Std, in (mm) ............... 3.8583-3.8594 (98.000-98.030)
Cylinder Liner Bore Diameter, Limit, in (mm) ............... 3.8661 (98.200)
Cylinder Liner Bore Taper Limit, in (mm) ............... 0.0008 (0.020)
Cylinder Block Top Surface Flatness Limit, in (mm) ............... 0.0020 (0.05)
Crankshaft Main Bearing Bore Diameter, in (mm) ............... 2.9528-2.9535 (75.000-75.020)
Crankshaft Main Journal Diameter, in (mm) ............... 2.7552-2.7559 (69.980-70.000)
Crankpin Journal Diameter, in (mm) ............... 2.2827-2.2835 (57.980-58.000)
Crankshaft Runout Standard, in (mm) ............... 0.0012 (0.030)
Crankshaft Main Bearing Oil Clearance, in (mm) ............... 0.0015-0.0033 (0.039-0.085)
Crankshaft Center Journal Thrust Clearance, in (mm) ............... 0.0024-0.0094 (0.060-0.240)
Connecting Rod Bearing Oil Clearance, in (mm) ............... 0.0014-0.0031 (0.035-0.080)
Piston Outer Diameter, in (mm) ............... 3.8563-3.8575 (97.950-97.980)
Piston to Cylinder Liner Clearance, in (mm) ............... 0.0016-0.0031 (0.040-0.080)
Piston Pin Outside Diameter, in (mm) ............... 1.2596-1.2600 (31.995-32.005)
Piston Pin Bushing Inner Diameter, in (mm) ............... 1.2604-1.2612 (32.015-32.035)
Piston Pin to Bushing Clearance, in (mm) ............... 0.0004-0.0016 (0.010-0.040)
First Ring Groove Width, in (mm) ............... 0.0965-0.0976 (2.450-2.480)
Second Ring Groove Width, in (mm) ............... 0.0791-0.0803 (2.010-2.040)
Oil Ring Groove Width, in (mm) ............... 0.1776-0.1787 (4.510-4.540)
First Ring Side Clearance, in (mm) ............... 0.0028-0.0045 (0.070-0.115)
Second Ring Side Clearance, in (mm) ............... 0.0016-0.0031 (0.040-0.080)
Oil Ring Side Clearance, in (mm) ............... 0.0008-0.0024 (0.020-0.060)
First Ring End Gap, in (mm) ............... 0.0118-0.0177 (0.300-0.450)
Second Ring End Gap, in (mm) ............... 0.0118-0.0177 (0.300-0.450)
Oil Ring End Gap, in (mm) ............... 0.0118-0.0177 (0.300-0.450)
Valve Guide Inner Diameter, in (mm) ............... 0.3543-0.3551 (9.000-9.020)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.3514-0.3522 (8.925-8.945)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.3504-0.3512 (8.900-8.920)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.075)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0024-0.0039 (0.060-0.100)
Intake Valve Thickness, in (mm) ............... 0.0630 (1.60)
Exhaust Valve Thickness, in (mm) ............... 0.0512 (1.30)
Valve Spring Free Length, in (mm) ............... 1.8898 (48.00)
Camshaft Bearing Bore Diameter, in (mm) ............... 2.0472-2.0480 (52.000-52.020)
Camshaft Journal Diameter, in (mm) ............... 1.9673-1.9681 (49.970-49.990)
Camshaft Bearing Oil Clearance, in (mm) ............... 0.0010-0.0033 (0.025-0.085)
Cam Lobe Height, Intake, in (mm) ............... 1.6547 (42.030)
Cam Lobe Height, Exhaust, in (mm) ............... 1.6547 (42.030)
Camshaft Runout Standard, in (mm) ............... 0.0008 (0.020)
Camshaft Thrust Clearance, in (mm) ............... 0.0020-0.0059 (0.050-0.150)

Tightening Torques

Cylinder Head Bolt (First Step), lb-ft (Nm) ............... 43.4 (58.8)
Cylinder Head Bolt (Final Step), lb-ft (Nm) ............... 72.3-79.5 (98.1-107.9)
Main Bearing Cap Bolt, lb-ft (Nm) ............... 101.2-115.7 (137.3-156.9)
Connecting Rod Bearing Cap Nut , lb-ft (Nm) ............... 57.9-65.1 (78.4-88.2)
Flywheel Bolt, lb-ft (Nm) ............... 86.8-94.0 (117.7-127.5)
Crankshaft Damper Pulley Bolt, lb-ft (Nm) ............... 144.7-159.1 (196.1-215.7)
Camshaft Timing Gear Bolt, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Rocker Arm Shaft Bracket Bolt, lb-ft (Nm) ............... 15.9-21.7 (21.6-29.4)
Valve Adjusting Screw Lock Nut, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)
Cylinder Head Cover Nut, lb-ft (Nm) ............... 5.8-8.7 (7.8-11.8)
Oil Pan Drain Plug, lb-ft (Nm) ............... 36.2-50.6 (49.0-68.6)
Oil Pan Mounting Bolt, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)
Timing Gear Case Bolt, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)
Flywheel Housing Bolt, lb-ft (Nm) ............... 36.2-47.0 (49.0-63.7)
Exhaust Manifold Nut, lb-ft (Nm) ............... 15.9-21.7 (21.6-29.4)
Intake Manifold Bolt, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)
Injection Pump Drive Gear Nut, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Injection Pump Mounting Bolt, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)
Injection Nozzle Holder Assembly, lb-ft (Nm) ............... 43.4-50.6 (58.8-68.6)
Nozzle Holder Retaining Nut, lb-ft (Nm) ............... 25.3-32.5 (34.3-44.1)
Fuel Injection Pipe Nut, lb-ft (Nm) ............... 18.1-25.3 (24.5-34.3)
Glow Plug, lb-ft (Nm) ............... 14.5-21.7 (19.6-29.4)
Oil Pump Mounting Bolt, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)
Water Pump Mounting Bolt, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)
Thermostat Housing Bolt, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)
Oil Cooler Assembly Bolt, lb-ft (Nm) ............... 15.9-21.7 (21.6-29.4)
Oil Filter Bracket Bolt, lb-ft (Nm) ............... 15.9-21.7 (21.6-29.4)
Starter Motor Mounting Bolt, lb-ft (Nm) ............... 57.9-72.3 (78.4-98.1)
Alternator Mounting Bolt, lb-ft (Nm) ............... 25.3-36.2 (34.3-49.0)
Fan Clutch Mounting Nut, lb-ft (Nm) ............... 13.0-17.4 (17.6-23.5)

________________________________________________________________________________________

• Isuzu Engines Specs
  
• Isuzu 4BB1 Specs
  
• Isuzu 4BC1 Specs
  
• Isuzu 4BC2 Specs
  
• Isuzu 4BD1 Specs
  
• Isuzu 4BD1T Specs
  

______________________________________________________________________________________

________________________________________________________________________________________

_______________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________