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  1. Check the top deck of the block for distortion by running a straightedge along both sides, both ends, and diagonally. Check for distortion exceeding 0.006 in. (0.15mm), by attempting to insert an appropriate size flat feeler gauge between the block deck and the lower edge of the straightedge all along its length, in every direction shown. If distortion exceeds the limit, have the block top deck ground by a competent machine shop or, if distortion is excessive, replace the block.

    Fig. 1: A telescoping gauge or inside micrometer may be used to measure the cylinder diameter bore

    Fig. 2: Measure the diameter of each cylinder at three different depths; also, take three additional readings, perpendicular to the first ones

    Fig. 3: Measure the piston's outside diameter using a micrometer

  2. Also inspect the block for cracks or wetness, indicating coolant has leaked through the cracks. If you have any doubt about such problems, you should have the block inspected by the Zyglo® , Magnaflux® or similar process, to ensure it can be reused without risk of leakage. Pressure testing is another means by which the block may be tested for cracks.

    NOTE: The Zyglo® process coats parts with a fluorescent dye penetrant that is suitable for any material. Magnaflux® is a magnetic process applicable only to ferrous materials.

  3. Measure the diameter of each cylinder at the six locations shown. Subtract the minimum dimension from the maximum dimension. If this difference exceeds 0.0059 in. (0.15mm), or the difference between cylinders exceeds 0.0007 in. (0.01778mm), cylinders must be bored and oversize pistons installed. If boring is required, you should base the amount that you remove on the dimensions of an oversize piston. When one cylinder is bored, all other cylinders must be bored the same amount. Any time this type of machining is done, it should be documented. Wall scoring or signs of piston seizure also mean cylinders must be rebored.

    NOTE: Even if only one cylinder is damaged, all must be bored and the same oversize pistons installed (for balance). Pistons are offered in oversizes of 0.010 in. (0.254mm) and 0.020 in. (0.508mm) for most engines.

    Fig. 4: Measure piston diameter at the position shown

    Fig. 5: Use a ring expander tool to remove the piston rings

    Fig. 6: Clean the piston grooves using a ring groove cleaner . . .

    Fig. 7: . . . or part of a broken piston ring. Be careful, since the ring is sharp

  4. On 2.0L (Code FE), 2.2L and 3.0L engines, test the oscillation torque of the rod by holding the piston in a horizontal position, and raising the rod until it touches the piston skirt, then releasing it. The rod should descend freely; otherwise, replace the piston and/or piston pin. If replacement is indicated, press the piston pin out with tools designed for this purpose.

    NOTE: This procedure requires the use of a hydraulic press that produces and measures total pressures of 1,100–3,300 lbs. (500–1,500 kg). You may wish to remove the piston/rod assemblies yourself and have the pressing operations performed at a competent automotive machine shop.

  5. On gasoline engines, other than the 1.3L engine, if the pressure required to press the pin from the piston is less than 1,100 lbs. (500 kg), replace the piston pin or the connecting rod.
  6. Measure piston diameter in the thrust direction, below the bottom of the oil ring groove and 90 degrees from the piston pin, as shown in the illustration. This dimension must compare with cylinder diameter so as to produce piston-to-cylinder clearance that is within specifications. If clearance exceeds the maximum wear specification, all cylinders must be bored and appropriate oversize pistons must be installed. If the clearance is within specification, only light finish honing is required.
  7. Using a ring expander tool, as illustrated, remove the piston rings. The various rings on each piston are not identical. Be careful not to mix them up, in case they may be reused.

    NOTE: If the piston is to be replaced, also install new piston rings.

  8. Clean the pistons thoroughly with a suitable solvent or in a dip tank. All the ring lands must be free and clear of any carbon deposits. Use a ring groove cleaning tool or a broken piston ring, which allows you to reach the innermost part of the land. DO NOT use a file or wire brush to clean the piston. Inspect the rings for damage or cracks and measure side clearance, as shown, using a new piston ring. Also measure end-gap, as shown, with the rings near the bottom of the cylinder — below the area of ring wear. This should be done even for new rings.
  9. Install the connecting rods in a jig designed to test straightness and check that the bend or twist does not exceed 0.0016 in. (0.04mm) per 3.94 in. (100mm) of length on all 1978–88 gasoline engines. On 1989 1.6L engines, the bend or twist should not exceed 0.0078 in. (0.20mm) per 3.94 in. (100mm), and on 1989 2.2L and 3.0L engines, the limit is 0.0024 in. (0.06mm).
  10. Measure the piston pin diameter and the piston pin hole diameter each in eight places, as illustrated. Compare the readings and replace any out-of-round components. Also, if pin-to-hole clearance is beyond the specified limit, replace the piston and/or piston pin.

    Fig. 8: Check the piston ring side clearance using a new ring and a feeler gauge

    Fig. 9: Measure ring end-gap by placing the ring inside the cylinder, in the area of ring-induced wear. Use an inverted piston to keep the ring from cocking

    Fig. 10: Use an inside caliper to measure the piston pin hole diameter in eight places

    Fig. 11: Use a micrometer to take eight measurements of a piston pin

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