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Engine Mechanical: Diagnosis Suzuki Forenza I

Mechanical 1 illustration ~644 words

Compression Test

WARNINGDisconnect the Crankshaft Position (CKP) Sensor connector to disable the fuel and the ignition systems.

Test the compression pressure for each cylinder. Low compression pressure may be the fault of the valves or the pistons. The following conditions should be considered when you check the cylinder compression

  1. The engine should be at normal operating temperature.
  2. The throttle must be wide open.
  3. All the spark plugs should be removed.
  4. The battery must be at or near full charge.
  1. Place approximately three squirts of oil from a plunger-type oiler into each spark plug port.
  2. Insert the engine compression gauge into each spark plug port.
  3. Crank test each cylinder with four to five compression strokes using the starter motor.
  4. The lowest reading should not be less than 70% of the highest reading. The compression gauge reading should not be less than 689 kPa (100 psi) for any of the cylinders.
  5. Examine the gauge readings obtained after the four "puffs" per cylinder are obtained from cranking the starter motor. The readings are explained in the following descriptions: Normal Condition - Compression builds up quickly and evenly to the specified compression on each cylinder. Piston Rings Faulty - Compression is low on the first stroke and tends to build up on following strokes, but the compression pressure does not reach normal. The compression pressure improves considerably with the addition of oil into the cylinder. Valves Faulty - Low compression pressure on the first stroke. The compression pressure does not tend to build up on the following strokes. The compression pressure does not improve much with the addition of oil into the cylinder.

Connecting Rod Bearing Noise Symptom

StepActionValue(s)YesNo
1Is a knock noise heard under all engine speeds?Step 2 System OKSystem OK
2Inspect the crankshaft connecting rod journal. Is the crankshaft connecting rod journal worn?Go to Crankshaft Disassembly and Assembly .Go to Step 3
3Check the oil pump pressure. Is the oil pump pressure low?Go to OIL PRESSURE TEST .Go to Step 4
4Inspect the crankshaft connecting rod journals. Are the journals out-of-round?Go to Crankshaft Disassembly and Assembly .Go to Step 5
5Inspect the connecting rods. Is there a misaligned connecting rod?Go to Pistons and Rods Removal and Installation .Go to Step 6
6Inspect the connecting rod bolts. Are the connecting rod bolts torqued properly?System OKGo to Pistons and Rods Removal and Installation .

CONNECTING ROD BEARING NOISE SYMPTOM CHART

Crankshaft Bearings and Connecting Rod Bearings - Gauging Plastic Inspection

Tools Required

KM-470-B Angular Torque Gauge

Scheme 3

Scheme 3
Scheme 3
  1. Coat the crankshaft bearings with engine oil.
  2. Install the upper crankshaft bearings into the engine block crankshaft journals.
  3. Install the lower crankshaft bearings into the crankshaft bearing caps.
  4. Install the crankshaft.
  5. Inspect the crankshaft end play with the crankshaft bearings installed.
  6. Check for permissible crankshaft end play. Refer to «Engine Specifications»(ref-257073-S42207845222007062900000) .
  7. With the crankshaft mounted on the front and rear crankshaft bearings, check the middle crankshaft journal for permissible out-of-round (runout). Refer to «Engine Specifications»(ref-257073-S42207845222007062900000) .
  8. Inspect all of the crankshaft bearing clearances using a commercially available plastic gauging (ductile plastic threads).
  9. Cut the plastic gauging threads to the length of the bearing width. Lay them axially between the crankshaft journals and the crankshaft bearings.
  10. Install the crankshaft bearing caps.
  11. Install the crankshaft bearing cap bolts. Tighten: Tighten the crankshaft bearing cap bolts to 50 N.m (37 lb-ft). Using the angular torque gauge KM-470-B, tighten the crankshaft bearing cap bolts another 45° plus 15°.
  12. Remove the crankshaft bearing caps.
  13. Measure the width of the flattened plastic thread of the plastic gauging using a ruler. (Plastic gauging is available for different tolerance ranges.)
  14. Inspect the bearing clearances for permissible tolerance ranges. Refer to «Engine Specifications»(ref-257073-S42207845222007062900000) .

Inspection - Connecting Rods

  1. Coat the connecting rod bearings with engine oil.
  2. Install the upper connecting rod bearings into the connecting rod journals.
  3. Install the lower connecting rod bearings into the connecting rod bearing caps.
  4. Inspect all of the connecting rod bearing clearances using a commercially available plastic gauging (ductile plastic threads).
  5. Cut the plastic gauging threads to the length of the bearing width. Lay them axially between the connecting rod journals and the connecting rod bearings.
  6. Install the connecting rod bearing caps.
  7. Install the connecting rod bearing cap bolts. Tighten: Tighten the connecting rod bearing cap bolts to 35 N.m (26 lb-ft). Using the angular torque gauge KM470-B, tighten the connecting rod bearing cap bolts another 45° plus 15°.
  8. Remove the connecting rod bearing caps.
  9. Measure the width of the flattened plastic thread of the plastic gauging using a ruler. (Plastic gauging is available for different tolerance ranges.)
  10. Inspect the bearing clearance for permissible tolerance ranges. Refer to «Engine Specifications»(ref-257073-S42207845222007062900000) .

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