Table of Contents
Related Manuals for Isuzu L Series
Summary of Contents for Isuzu L Series
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Page 1: Table Of Contents
VII. Appendix – Misc. Service Information Nozzle Troubleshooting Guide Nozzle Performance & Diagnosis Nozzle Holder Tightening Specifications 43-44 Turbo Diagnosis Exhaust Temperature Crankcase Pressure Inlet Manifold Pressure Used Oil Analysis Isuzu Technology – L-Series Direct Injection VIII. 48-49 L-Series Diesel... -
Page 2: Foreword
Foreword This book is designed to cover several aspects of the L-series engines. L-series engines currently in production are the 3LA, 3LB, 3LD, 4LB, 4LC, and the 4LE. This training manual is divided into six sections to make referencing information easier. The introduction covers engine application notes and maintenance schedule. -
Page 3: Introduction Application Notes
There are several L-series engines that are CARB (California Air Resource Board) certified. CARB emissions standards for the L series apply to engine models in the 11-25 hp range and 25-50 hp range. To meet the new CARB standards, the pump’s injection timing has been changed. -
Page 4: Maintenance Schedule
The following maintenance schedule is a comprehensive service program that takes a preventative approach to engine repair. Isuzu has established these standards with maintenance as the basis for prolonged product life. Isuzu highly recommends that if a routine maintenance schedule is not part of your customer support service, one should be implemented to better serve the needs of your customers. -
Page 5: General Family Information
• Electric fuel pump purges air automatically Identification The production date for any Isuzu engine can be obtained be reading the letter codes on the ID tag (usually located on the head cover) and using the table below. Example: BA/JB=10/91 (Engine produced October, 1991). -
Page 6: Engine Component Description
II. Engine Component Description Pump Description Plunger Timing Sleeve All L-series engines use individual injection pumps to supply fuel to the injection nozzles. The fuel pumps are mounted to the engine block, and are operated by the camshaft. Inside of the pump, there is a plunger barrel, timing sleeve, and plunger assembly. - Page 7 II. Engine Component Description Pump Timing This drawing shows the relationship between cam lift and cam angle when pre-stroke length is changed. The stroke length represented as “L” is always constant. When the pumps are advanced by using a thinner shim, the timing sleeve is lowered and the start of injection occurs at the beginning of the cam lift.
- Page 8 II. Engine Component Description Pump Injection Sequence Intake Fuel enters the high-pressure chamber from the intake port. However, even though the plunger begins to rise, pressure inside the chamber does not increase because the fuel from the inlet port flows back into the fuel reservoir via the spill-port hole Beginning of Injection As the plunger rises, it blocks the spill...
- Page 9 II. Engine Component Description Pump Injection Sequence (continued) Pressure Feeding Since the intake port and helix are kept closed by the timing sleeve, fuel pressure continues to rise, the delivery valve opens, and fuel flows to the injector. End of Injection On the return stroke, when the plunger helix reaches the timing sleeve’s spill port, the pressurized fuel flows through...
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Page 10: Valve Train
II. Engine Component Description Valve Train L-series engines use individual rocker arms Do not seal oil galley mounted on a common shaft. The rockers and with liquid gasket. shaft are mounted inside the rocker bracket assembly. Both components can be removed for servicing by simply removing the balance shaft’s retaining plug at the rear of the bracket. -
Page 11: Camshaft
II. Engine Component Description Camshaft Design The camshaft is a cast iron billet and has lobes for both the valves and fuel pumps. The cam is supported by two ball bearings and a needle bearing (located in the center of the block) to reduce friction and improve shaft durability. -
Page 12: Crank, Block, Pistons, Rods
NOTE: The dampers should NEVER be interchanged. Excessive engine vibration and damage will occur. IMPORTANT: The crank is hardened using Tufftriding. Isuzu does recommend grinding crankshaft undersize. L-Series Diesel... - Page 13 II. Engine Component Description Cylinder Block The engine’s serial number is stamped on the front of the engine block. This number is used by parts technical personnel to track an engine's application or verify a specification. Also shown are the castings in the block for the individual injection pumps.
- Page 14 If the engine is out of warranty, pistons are available for cylinders bored .010 over. Boring the cylinders and use of oversize pistons is not approved for Isuzu warranty repairs. TIP: Previously, pistons were bore sized and identified with grade lettering for service replacement.
- Page 15 NOTE: When removing and replacing the connecting rod assemblies, be sure to install the connecting rod with the Isuzu Logo facing the same direction as the piston’s forward notch. IMPORTANT: The rod cap bolts are not to be removed.
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Page 16: Head Gasket
II. Engine Component Description Cylinder Head Gasket The L-series engines use a three layer ultra thin laminated steel head gasket that requires no retorqueing after the engine break-in period. Holes for coolant are drilled between the valve seats for effective cooling of the combustion area. -
Page 17: Cylinder Head
The service limit for this engine is 370 psi (26.0 kg/cm ). Standard pressure is 441 psi (31.0 kg/cm ). Isuzu allows an 8% variance between cylinders on compression tests, but there can be no more than a 15% difference between any two cylinders. -
Page 18: Lubrication
II. Engine Component Description Lubrication Lubrication is achieved with a conventional wet sump oiling system. Internally, the trochoid oil pump uses a set of rotors instead of spur gears. It is a very efficient and smooth operating pump. Compared with the spur gear type pump, the trochoid pump gives practically continuous flow, due to less leakage on the discharge side of the pump. - Page 19 II. Engine Component Description Lubrication (continued) Below is the oil full flow diagram. Note the valve opening pressure for the oil filter bypass valve (14 PSI is where the valve begins to open. The same is true for the oil pump relief valve, which begins to open at 64 PSI.).
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Page 20: Cooling
II. Engine Component Description Cooling System Below is the coolant flow diagram. Good coolant circulation is ensured by utilizing water jackets formed with a one-piece casting core, which eliminates burrs in the water passage. Maintain a coolant/water solution concentration ratio of . -
Page 21: Engine Servicing Procedures
Spill-port timing is a precise method of measuring the initial injection of fuel by the pump and the duration of injection. It is a standard procedure used by Isuzu when timing Zexel pumps. This procedure is a very precise method of timing fuel because... -
Page 22: Valve Adjustment
III. Engine Servicing Procedures Valve Adjustment Bring the engine up on number one compression stroke. Verify the position by checking for clearance in-between the valve stem tip and the rocker arm. NOTE: Valves can be adjusted beginning with #1 or #3 (3L) or #4 (4L). This adjustment can only be made with a cold engine. -
Page 23: Injector Service
III. Engine Servicing Procedures Injector Service The following procedures are service recommendations from Zexel: Thoroughly clean all carbon residue and carbon build–up on the surface of the nozzle using Zexel cleaning #1057790010. Soak all parts other than the nozzle in cleaning oil. - Page 24 III. Engine Servicing Procedures Injector Service (continued) Remove the needle valve from the nozzle. Clean the seat’s surface and shaft section using the piece of hardwood from the cleaning kit or a clean soft cloth dipped in oil. Likewise, clean the spray hole with the special needle also supplied with the cleaning kit.
- Page 25 III. Engine Servicing Procedures Injector Service (continued) Note: Before assembling the injector, perform a needle slide test to ensure that there is no obstruction that could cause a fuel leak. Insert the body nozzle holder to center the nozzle in the retaining nut. For reassembly torque specifications, Appendix...
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Page 26: Injector Pop-Off Test
III. Engine Servicing Procedures Injector Pop-off Test WARNING: FLUID FROM THE NOZZLE TESTER WILL SPRAY OUT UNDER GREAT PRESSURE. IT CAN EASILY PUNCTURE A PERSON’S SKIN. KEEP YOUR HANDS AWAY FROM THE NOZZLE TESTER AT ALL TIMES. Use the following procedure to check nozzle opening pressure, spray pattern, chatter and leakage: Mount the nozzle and holder assembly to... -
Page 27: Injector Leak Test
III. Engine Servicing Procedures Injector Leak Test leak test should conducted immediately following the nozzle opening pressure adjustment check. ⇒ Wipe the nozzle with a clean shop towel. ⇒ Decrease the tester pressure about 20 kg/cm less than the pop-off pressure and maintain the position. -
Page 28: Hot Plug Replacement
III. Engine Servicing Procedures Hot Plug Replacement Hot plugs for the L-series are similar to other Isuzu diesel engines. If the plug needs to be replaced, knock out the old plug from behind, though the injector nozzle hole. Always remember that the plug groove in... -
Page 29: Engine Repair Specifications - 3L
IV. Engine Repair Specifications – 3L Maintenance Specifications Item Metric Measure US Measure Engine Oil Capacity ¬ 3LA/B1 5.1 Liters 5.4 quarts 3LD1 6.8 Liters 7.2 quarts Engine Oil Pressure Ä 4-5 Kg/cm 43-51 lbs Compression Pressure - 441 psi - 31 Kg/cm .40 ±... - Page 30 IV. Engine Repair Specifications – 3L Mechanical Specifications Cylinder Head/ Valve Train Standard Service Limit Valve Clearance¬ 0.40 mm/ 0.01575 in 0.025 mm/ 0.010 in Cylinder head Warpage- 0.075 mm/ 0.0029 in 0.15 mm/ 0.0059 in Cylinder Head Height ® 64.0 mm/ 2.5197 in 63.7 mm/ 2.5079 in Valve Depression ¯...
- Page 31 IV. Engine Repair Specifications – 3L Torque Specifications Cylinder Head/ Valve Train Kg m lb/ft Cylinder Head Torque¬- + 30° + 30° ® M12 x 1.5 8.5-9.5 + 60° 61-69 + 60° -0° -0° M8 x 1.25 2.5-3.5 18-25 Valve lash adjusting jamb nut 0.8-1.2 5.8-8.7 Valve cover bolts...
- Page 32 IV. Engine Repair Specifications – 3L Lubrication and Sealant Specifications Application Thread Lockers Lubricants Sealant Flywheel Bolts --------------------------- Engine Oil ------------------------ Oil Pan --------------------------- --------------------------- TB1207C Rocker Bracket¬ --------------------------- --------------------------- TB1207C Air Inlet Pipe --------------------------- --------------------------- TB1207C Front Plate (PTO --------------------------- --------------------------- TB1207C only)
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Page 33: Engine Repair Specifications - 4L
V. Engine Repair Specifications – 4L Maintenance Specifications Item Metric Measure US Measure Engine Oil Capacity ¬ 4LB1/LC1 7.3 Liters 7.7 quarts 4LE1 8.7 Liters 9.2 quarts Engine Oil Pressure Ä 4-5 Kg/cm 43-51 lbs Compression Pressure - 31 Kg/cm 441 psi .40 ±... - Page 34 V. Engine Repair Specifications – 4L Mechanical Specifications Cylinder Head/ Valve Train Standard Service Limit Valve Clearance¬ 0.40 mm/ 0.01575 in ------------------------------------ Cylinder Head Warpage- 0.075 mm/ 0.0029 in 0.15 mm/ 0.0059 in Cylinder Head Height ® 63.9 mm/ 2.515 in 64.1 mm/ 2.523 in Valve Depression ¯...
- Page 35 V. Engine Repair Specifications – 4L Torque Specifications Cylinder Head/ Valve Train Kg m lb/ft Cylinder Head Torque¬- M12 x 1.5 8.5-9.5 + 60°~90° 61-69 + 60°~90° M8 x 1.25 2.5-3.5 18-25 Valve lash adjusting jamb nut 0.8-1.2 5.8-8.7 Valve cover bolts 0.2-0.4 1.4-2.9 Exhaust Manifold...
- Page 36 V. Engine Repair Specifications – 4L Lubrication and Sealant Specifications Application Thread Lockers Lubricants Sealant Flywheel Bolts --------------------------- Engine Oil ------------------------ Oil Pan --------------------------- --------------------------- TB1207C Rocker Bracket¬ --------------------------- --------------------------- TB1207C Air Inlet Pipe --------------------------- --------------------------- TB1207C Front Plate (PTO --------------------------- --------------------------- TB1207C only)
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Page 37: Component Failure Analysis
VI. Component Failure Analysis Fuel System Nozzle Holder component failure Description: Broken coil on the holder spring directly related to large amounts of carbon build – up on the nozzle spring. Carbon build-up can also be seen on the push rod. This condition is directly related to combustion gases passing through the nozzle holder spring chamber. - Page 38 VI. Component Failure Analysis Fuel System Nozzle component failure (continued) Description: Corrosive abrasion of the pintal nozzle edge caused by direct contact with blow-by of the combustion gases in the combustion chamber. Description: Nozzle seat damage caused by metal contaminants in the fuel that pressed onto the seat area.
- Page 39 VI. Component Failure Analysis Fuel System Nozzle component failure (continued) Description: Damage to the nozzle seat and spray hole sections when the nozzle holder is over tightened. Cylinder Block Description: Damaged head gasket, cylinder head, pistons, connecting rods and crankshaft caused by poor cylinder block casting, cooling system cavitation, or cooling system electrolysis.
- Page 40 VI. Component Failure Analysis Piston Description: Piston Failure due to reusing a previously cracked piston skirt. Description: Broken piston skirt tang due to excessive piston to wall clearance. (Creates piston slap sound). Description: Seized piston skirt due to insufficient piston to wall clearance. (a.k.a. piston galling).
- Page 41 VI. Component Failure Analysis Piston Failure Description: A wrist pin seized in this bore due to a previously used bent wrist pin or damaged piston pin bore. Description: (Normal piston skirt wear) L-Series Diesel...
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Page 42: Nozzle Troubleshooting Guide
VII. Appendix – Miscellaneous Service Information NOZZLE L-Series Diesel... -
Page 43: Nozzle Performance & Diagnosis
VII. Appendix – Miscellaneous Service Information L-Series Diesel... -
Page 44: Nozzle Holder Tightening Specifications
VII. Appendix – Miscellaneous Service Information L-Series Diesel... - Page 45 VII. Appendix – Miscellaneous Service Information L-Series Diesel...
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Page 46: Turbo Diagnosis
VII. Appendix – Miscellaneous Service Information Turbocharger Boost Pressure Diagnosis Listen below are suggested checks for determining the cause of lowered turbo boost pressure (in the sequence they should be performed). To obtain maximum boost pressure, the engine must be operated at rated RPM under a full load condition. Boost pressure is measured with a mercury manometer. -
Page 47: Exhaust Temperature
The results of all three of these tests will vary between engine models and between specifications of the same model. To find the specifications applicable to your particular engine, reference American Isuzu Motors Inc. Engine & Components Operations Publication #SV-5013-00 (“Engine Service Specifications Manual”). -
Page 48: Used Oil Analysis
VII. Appendix – Miscellaneous Service Information Used Oil Sample Data (Limits) Item Unit of Limit Measurement Kinematic Viscosity -20 to 50% of new oil (@ 98.9°C (CST)/210° F Total Base No. KOH mG/G 1 (min.) Total Acid No. KOH mG/G 3 (max.) B-Heptane Insoluble Wt %... -
Page 49: Isuzu Technology: L-Series Direct Injection
With the new DI three cylinder model 3LD2 displacing 1499 cc and the four cylinder 4LE2 displacing 2179 cc, the L- Series is the smallest series that Isuzu manufactures today. The 3LD2 has a bore and stroke of 83.1 x 92 mm and a maximum output of 34.8 hp at 3000 rpm, with peak torque of 73.5 lb.ft. - Page 50 The L-Series reputation for leak-free operation should be continued, always a strong point for Isuzu. The fuel system is also self-bleeding and self-priming, meaning that should the operator run out of fuel, he can just add fuel and restart the engine.
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