Engine Mechanical: Diagnosis Isuzu Axiom I

ENGINE DIAGNOSIS

First of all the engine diagnose to check the fuel quantity, the engine level and the engine coolant level.

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Spark Test

Disconnect an ignition coil from any spark plug. Connect the spark plug tester (For example J-26792), start the engine, and check if a spark is generated in the spark plug tester. Before starting the engine, make sure that the spark plug tester is properly grounded. To avoid electrical shock, do not touch the part where insulation of the ignition coil is broken while the engine is running.

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ENGINE COMPRESSION TEST PROCEDURE

1. Start and run the engine until the engine reaches normal operating temperature.
2. Turn the engine off.
3. Remove all the spark plugs.
4. Remove ignition coil fuse (15A) and disable the ignition system.
5. Remove the fuel pump relay from the relay and fuse box.
6. Engage the starter and check that the cranking speed is approximately 300 RPM.
7. Install cylinder compression gauge into spark plug hole.
8. With the throttle valve opened fully, keep the starter engaged until the compression gauge needle reaches the maximum level. Note the reading.
9. Repeat the test with each cylinder.

If the compression pressure obtained falls below the limit, engine overhaul is necessary.

Limit; 1000 kPa (145 psi)

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Troubleshooting Procedure For Connecting Rods Or Connecting Rod Bearing Noise

Short out each spark plug in sequence using insulated spark plug wire removers. Locate cylinder with defective bearing by listening for abnormal noise that stops when spark plug is shorted out.

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Troubleshooting Procedure For Piston And Cylinder Noise

Abnormal noise stops when the spark plug on the cylinder with defective part is shorted out.

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Troubleshooting Procedure For Piston Pin Noise

Short out each spark plug and listen for change in engine noise.

TROUBLESHOOTING PROCEDURE FOR PISTON PIN NOISE

Troubleshooting Procedure For Slapping Or Hitting ETC Noise

The slapping sound stops when spark plug on bad cylinder is shorted out.

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Inspection And Repair For Bearings

1. Inspect Crankshaft

Set the dial indicator as shown in the illustration and measure the crankshaft thrust clearance. If the thrust clearance exceeds the specified limit, replace the thrust bearings as a set.

Thrust Clearance

Standard: 0.06 mm - 0.24 mm (0.0024 in - 0.0094 in)

Limit: 0.30 mm (0.0118 in)

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1. Remove the bearing caps and measure the oil clearance.
2. Remove the main bearing cap fixing bolts in the sequence shown in the illustration. Arrange the removed main bearing caps in the cylinder number order. Remove the main bearings.
3. Remove the crankshaft. Remove the main bearings.
4. Clean the upper and lower bearings as well as the crankshaft main journal.
5. Check the bearings for damage or excessive wear. The bearings must be replaced as a set if damage or excessive wear is discovered during inspection.
6. Set the upper bearings and the thrust washers to their original positions. Carefully install the crankshaft.
7. Set the lower bearings to the bearing cap original position.
8. Apply plastigage to the crankshaft journal unit as shown in the illustration. NOTE: Do not set the plastigage on the oil hole.
9. Install main bearing caps, oil gallery and crank case bolts in the order shown, and tighten each bolt to the specified torque. NOTE: Do not apply engine oil to the crank case side bolts. Main bearing cap bolts. Torque: 39 N.m (29lb ft) Oil gallery fixing bolts. Torque: 1st step: 29 N.m (22 lb ft) 2nd step: 55°- 65° Crank case side bolts Torque: 39 N.m (29lb ft) NOTE: Do not allow the crankshaft to rotate.
10. Remove the main bearing caps in the sequence shown in the illustration.
11. Measure the plastigage width and determine the oil clearance. If the oil clearance exceeds the specified limit, replace the main bearings as a set and/or replace the crankshaft. Standard: 0.019 mm - 0.043 mm (0.0007 in - 0.0017 in) Limit: 0.08 mm (0.0031 in)
12. Clean the plastigage from the bearings and the crankshaft.

Remove the crankshaft and the bearings.

Crankshaft Inspection

Inspect the surface of the crankshaft journal and crank pins for excessive wear and damage. Inspect the oil seal fitting surfaces for excessive wear and damage. Inspect the oil ports for obstructions.

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1. Carefully set the crankshaft on the V-blocks. Slowly rotate the crankshaft and measure the runout. If the crankshaft runout exceeds the specified limit, the crankshaft must be replaced. Runout: 0.04 mm (0.0016 in)
2. Measure the diameter and the uneven wear of main journal and crank pin. If the crankshaft wear exceeds the specified limit, crankshaft must be replaced. Main journal diameter: 63.918 mm - 63.933 mm (2.5165 in - 2.5170 in) Crank pin diameter: 53.922 mm - 53.937 mm (2.1229 in. - 2.1235 in.) Uneven wear limit: 0.005 mm (0.0002 in)

Inspection and Repair

1. Remove the cylinder head gasket and any other material adhering to the upper surface of the cylinder block. Be very careful not to allow any material to accidentally drop into the cylinder block. Be very careful not to scratch the cylinder block.
2. Carefully remove the oil pump, rear oil seal retainer, and crankcase assembly installation surface seal.
3. Wipe the cylinder block clean.
4. Visually inspect the cylinder block. If necessary, use a flaw detector to perform a dye penetrate and hydraulic (or air pressure) test. If cracking or other damage is discovered, the cylinder block must either be repaired or replaced.