- Remove the cylinder head as outlined in the appropriate preceding section.
- Remove the oil pan and pump.
- Ream the ridge from the top of the cylinder bore (See Ridge Removal and Honing).
- Unbolt the connecting rod caps, after match marking each cap to its connecting rod.
- Place pieces of rubber hose over the rod bolts, to protect the cylinder walls and crank journals from scratches. Push the connecting rod and piston up and out of the cylinder from the bottom using a wooden hammer handle.
- Mark each connecting rod with the number of the cylinder from which it was removed.
CLEANING AND INSPECTION
Connecting Rod and Bearings
While the piston and rod assemblies are still installed, measure the rod thrust clearance with a dial indicator, while moving the connecting rod back and forth. Compare readings with the Engine Rebuilding Specification Chart. If the thrust clearance is greater than the maximum specification, replace the connecting rod and/or crankshaft.
To check the connecting rod, use a rod aligner and feeler gauge. Check the rod for bending. If the bend is greater than the maximum listed in the Engine Rebuilding Specification Chart, replace the connecting rod and cap as a set. Check for twist. If the twist is greater than the maximum listed in the Engine Rebuilding Specification Chart, replace the connecting rod and cap as a set.
To check the rod bearing oil clearance, remove the rod bearing (See Rod Bearing Replacement), then clean the crankpin and bearing with solvent. Check the surfaces for pitting or scratches. Lay a strip of Plastigage® across the crank pin. Install the rod cap and torque the nuts to specifications, making sure not to turn the crankshaft. Remove the rod cap and measure the Plastigage® to determine the oil clearance. Compare with specifications. If the clearance is too large, replace the bearings. Several sizes of standard sized bearings are available, identified by "Mark 1," "Mark 2," etc., without necessarily having to machine the crankshaft to achieve the proper clearances. If necessary, grind or replace the crankshaft to achieve the proper clearances.Pistons and Rings
Clean the piston after removing the rings, by first scraping any carbon from the piston top. Do NOT scratch the piston in any way during cleaning. Use a ring cleaning tool to clean out the ring grooves. Clean the entire piston with solvent and a brush (not a wire brush). Check the piston for cracks or other damage.RING END GAP
To check ring end-gap, insert a compression ring into the cylinder. Lightly oil the cylinder bore and push the ring down into the cylinder with a piston, to the bottom of its travel. Measure the ring end-gap with a feeler gauge. If the gap is not within specification, replace the ring; Do NOT file the ring ends.RING SIDE CLEARANCE
Once the piston is thoroughly cleaned, insert the side of a good piston ring (both No. 1 and No. 2 compression on each piston) into its respective groove. Using a feeler gauge, measure the clearance between the ring and its groove. If clearance is greater than the maximum listed under Ring Side Clearance in the Piston and Ring Chart, replace the ring(s) and if necessary, the piston.PISTON OIL CLEARANCE
- First, using a cylinder gauge, measure the cylinder bore diameter at positions A, B and C in the thrust and axial directions. The proper specifications depend on the size of the standard bore diameter, usually marked 1, 2 and 3 on the top of the cylinder block (See Engine Rebuilding Specification Chart).
- If the diameter is greater than maximum, rebore the 4 cylinders or replace the block.
Using a micrometer, measure the piston diameter at right angles to the piston pin center line:
- Measure at the proper distance from the piston head on the following engines: 0.886 in. (22.5mm) on the 4A-FE engine, 1.185 in. (30.1mm) on the 3S-GTE engine, 1.00 in. (25.4mm) on the 3S-FE engine or 0.925 in. (23.5mm) on the 5S-FE engine.
- Measure 0.59 in. (15mm) below the piston pin hole center line on the 2S-E engine.
- Measure 0.43 in. (11mm) above the piston pin hole center line on the 3S-GE engine.
- Compare this measurement to specifications for the particular size of the piston, usually marked 1, 2 or 3 on the top of the piston (See Engine Rebuilding Specification Chart).
- Subtract the piston diameter measurement from the cylinder bore diameter measurement to obtain the measured oil clearance. If not within specifications, replace the pistons and, if necessary, the cylinder block to achieve the proper clearances.
As the cylinder bore wears, a ridge is formed at the top of the cylinder, where the rings never scrape. Removing this ridge makes piston and ring removal easier. A ridge reamer is installed into the cylinder, tightened, then the cutters of the reamer are moved upward as the threaded portion of the reamer is rotated.
When new piston rings are installed in an engine, the cylinder bore must have a cross-hatch pattern finish. This allows the rings and bore to wear in together and in the long run provide better oil control and compression. This cross-hatch pattern is achieved by honing. No more than 0.0008 in. (0.02mm) should be removed during this process, since the finished roundness of the cylinder will be destroyed.
RIDGE REMOVAL AND HONING
PISTON PIN REPLACEMENT
Wrist pin and/or connecting rod small-end bushing wear can be checked by rocking the piston at a right angle to the wrist pin by hand. If any movement is felt, the pin, piston and/or rod must be replaced. The piston and pin are replaced as a set.2S-E, 3S-FE and 4A-FE Engines
- Remove the piston rings (See Piston Ring Replacement). Mark the fronts of the pistons and the rods for reassembly.
- Using a shop press and the proper adapters, press out the piston pin from the connecting rod.
- Coat the piston pin and pin holes of the piston with engine oil.
- Align the marks on the piston and rod, then install the rod pin with a shop press.
- Remove the piston rings (See Piston Ring Replacement). Mark the fronts of the pistons and rods for reassembly.
- Using a small tool, remove the snapring from the piston.
- Heat the cylinder pistons to 176°F (80°C) in a bath.
- Using a plastic-faced hammer, driver and holding device, lightly tap the wrist pin out of the piston. Remove the piston from the connecting rod.
- If necessary, replace the connecting rod bushing by removing with a press.
- Align the oil holes of the bushing and rod, then press the bushing into the rod. Machine the bushing, if necessary, to obtain the proper oil clearance (See Engine Rebuilding Specification Chart).
- Coat the pin with engine oil, then reverse the removal procedures to complete installation.
PISTON RING REPLACEMENT
- Using a piston ring expander, mark and remove the two compression rings one by one.
- Remove the two side rails and oil ring expander by hand. Always remove and replace the rings of each piston before going on to the next. This helps avoid mixing up the rings.
- Install the rings using the ring expander, starting with the top compression ring and working down. Make sure the code marks are facing up on each ring.
- Position the rings so that the ring and gaps are evenly spaced as in the illustration. Do NOT align the end gaps.
ROD BEARING REPLACEMENT
When the rod bearings are replaced, the bearing claw must fit in the groove of the connecting rod and cap. This prevents the bearing from spinning as the crankshaft rotates.
The pistons are marked with an arrow or notch in the piston head. When installed in the engine, the markings must be facing towards the front of the engine.
The connecting rods should be installed in the engine with the protrusion facing the front of the engine.
- Apply a light coating of engine oil to the pistons, rings, and outer ends of the wrist pins.
- Examine the piston to ensure that it has been assembled with its parts positioned correctly. Be sure that the ring gaps do NOT overlap.
- Place pieces of rubber hose over the connecting rod bolts, to keep the threads from damaging the crank journal and cylinder bore. Install the pistons, using a ring compressor, into the cylinder bore. Be sure that the appropriate marks on the piston are facing the front of the engine.
- Install the connecting rod bearing caps and tighten them to the torque figures given in the Torque Specifications Chart. Install the remaining components, using the proper procedures.