See Figures 1 through 6
See Figures 7 and 8
This procedure requires removal of most of the engine parts, including the head and pan. While it can be performed in the vehicle, removing the engine from the vehicle makes the job much easier. Mount the engine on an engine stand so that it may be rotated or moved about the work area. Before removing the piston assemblies, connecting rod bearing clearance and side clearance should be checked. Refer to the Connecting Rod Inspection procedure in this section.
- Remove the cylinder head.
- Remove the oil pan and pump.
- Position a cylinder ridge reamer into the top of the cylinder bore. Keeping the tool square, ream the ridges from the top of the bore. Clean out the ridge material with a solvent-soaked rag, or blow it out with compressed air.
- Remove the oil strainer. Use a numbered die set to mark each cap and connecting rod with its cylinder number. Unbolt the connecting rod caps.
- 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. Use a wooden hammer handle to push on the bottom of the piston top.
- Keep the piston and bearing cap together.
CLEANING AND INSPECTION
See Figures 9, 10, 11 and 12
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 broken piston ring or ring cleaning tool to clean out the ring grooves. Clean the entire piston with solvent and a stiff bristle brush (NOT a wire brush).
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.
Place a rag over the crankshaft journals (the part the rods connect to). Wipe out each cylinder with a clean, solvent-soaked rag. Visually inspect the cylinder bores for roughness, scoring or scuffing; also check the bores by feel. Measure the cylinder bore diameter with an inside micrometer, or a telescope gauge and micrometer. Measure the bore at points parallel and perpendicular to the engine centerline at the top (below the ridge) and bottom of the bore. Subtract the bottom measurements from the top to determine cylinder taper.
Measure the piston diameter with a micrometer; since this particular micrometer may not be part of your tool kit you may wish to have the pistons measured at a machine shop. Take the measurements at right angles to the wrist pin center line, about an inch down the piston skirt from the top. Compare this measurement to the bore diameter of each cylinder. The difference is the piston clearance. If the clearance is greater than that specified in the Piston and Ring Specifications chart, have the cylinders honed or rebored and replace the pistons with an oversize set.
Wash the connecting rods in cleaning solvent and dry them with compressed air. Check for twisted or bent rods and inspect for nicks or cracks. Replace the connecting rods that are damaged.
RIDGE REMOVAL AND HONING
- Before the piston is removed from the cylinder, check for a ridge at the top of the cylinder bore. This ridge occurs because the piston ring does not travel all the way to the top of the bore, thereby leaving an unused portion of cylinder bore.
- Clean away any carbon buildup at the top of the cylinder with sand paper, in order to see the extent of the ridge more clearly. If the ridge is slight, it will be safe to remove the pistons without damaging the rings or piston ring lands. If the ridge is severe, and easily catches your fingernail, it will have to be removed using a ridge reamer.
- Install the ridge removal tool in the top of the cylinder bore. Carefully follow the manufacturers instructions for operation. Only remove the amount of material necessary to remove the ridge.
- After the piston and connecting rod assembly have been removed, check the clearances as explained in the piston and connecting rod cleaning and inspection procedure, to determine whether boring and honing or just light honing are required. If boring is necessary, consult an automotive machine shop. If light honing is all that is necessary, proceed to the next step.
Honing is best done with the crankshaft removed, to prevent damage to the crankshaft and to make post-honing cleaning easier, as the honing process will scatter metal particles. However, if you do not want to remove the crankshaft, position the connecting rod journal for the cylinder being honed as far away from the bottom of the cylinder bore as possible, and wrap a shop cloth around the journal.
Honing can be done either with a flexible glaze breaker type hone or with a rigid hone that has honing stones and guide shoes. The flexible hone removes the least amount of metal, and is especially recommended if your piston-to-cylinder bore clearance is on the loose side. The flexible hone is useful to provide a finish on which the new piston rings will seat. A rigid hone will remove more material than the flexible hone and requires more operator skill.
- Regardless of which type of hone you use, carefully follow the manufacturers instructions for operation.
- The hone should be moved up and down the bore at sufficient speed to obtain a uniform finish. A rigid hone will provide a definite cross-hatch finish; operate the rigid hone at a speed to obtain a 45-65° included angle in the cross-hatch. The finish marks should be clean but not sharp, free from embedded particles and torn or folded metal.
- Periodically during the honing procedure, thoroughly clean the cylinder bore and check the piston-to-bore clearance with the piston for that cylinder.
- After honing is completed, thoroughly wash the cylinder bores and the rest of the engine with hot water and detergent. Scrub the bores well with a stiff bristle brush and rinse thoroughly with hot water. Thorough cleaning is essential, for if any abrasive material is left in the cylinder bore, it will rapidly wear the new rings and the cylinder bore. If any abrasive material is left in the rest of the engine, it will be picked up by the oil and carried throughout the engine, damaging bearings and other parts.
- After the bores are cleaned, wipe them down with a clean cloth coated with light engine oil, to keep them from rusting.
PISTON PIN REPLACEMENT
See Figures 13 through 19
Wrist pin and/or connecting rod (small-end) bushing wear can be checked by rocking the piston at right angles to the wrist pin by hand. If more than very slight movement is felt, the pin and/or rod bushing must be replaced.
Except for the 3VZ-E engine, the pistons for the engines covered here must be heated in hot water to expand them before the wrist pins can be removed and installed. The four cylinder pistons must be heated to a specific temperature range. This job can be performed at a machine shop if the idea of boiling pistons in the kitchen doesn't appeal to you. If you decide to do it, however, remember that each piston, pin and connecting rod assembly is a matched set and must be kept together until reassembly.
On the 3VZ-E, the piston pins can be removed or installed with a press, but special precautions must be observed. The tip of the press must be the diameter of the pin so that force is applied evenly. The piston must be supported on a broad surface with an opening below the pin hole. Force must be exerted precisely straight on to the pin; any cocking of the piston may result in cracking the piston.
Although this process can be accomplished if the correct tools are at hand, it is still recommended to have the pins pressed by either a dealer or machine shop; the slight cost outweighs the risk (and cost) of replacing an otherwise good piston.
- Using a small flat-bladded tool, pry out the 2 snaprings.
- On the 3VZ-E engines, use a press and SST 09221-25024 and 09221-00181 or equivalent to press the pin from the piston.
Excluding the 3VZ-E, gradually heat the piston to:
140°F (60°C)-22R, 22R-E and 5VZ-FE
- Using a plastic faced hammer and brass bar, lightly tap the pin out and remove the connecting rod.
The piston and pin are a matched set. Arrange the pistons, pins, rings, bearings and connecting rods in the correct order.To install:
- On the 3VZ-E engine, coat the piston pin and pin holes with engine oil. Align the front marks of the piston and connecting rod. (A1. B6, 1B, 8A, C3 or etc.) Using the SST or equivalent from removal, press in the piston pin.
- Excluding the 3VZ-E, install a new snapring on the one side of the piston pin hole. Gradually heat the piston to the correct temperature.
- Coat the pin with engine oil.
- Align the front marks of the piston and connecting rod, then push in the pin with your thumb.
- Install a new snapring on the other side of the hole.
PISTON RING REPLACEMENT
See Figures 20, 21, 22 and 23
The cylinder walls must be de-glazed (honed) when the piston rings are replaced. De-glazing insures proper ring seating and oil retention.
Using a piston ring expander, remove the rings one by one. Always remove and replace the rings of each piston before going on to the next. This helps avoid mixing up the rings. When the rings have been removed from each piston, perform the end gap procedure. The rings are marked on one side, the mark denoting the up side for installation.
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.
Install the rings using the ring expander, starting with the top compression ring and working down. Make sure the marks (T or N) are facing up on each ring. Position the rings so that the ring end gaps are staggered. Never align the end gaps nor with ANY gap facing the front of the cylinder.
ROD INSPECTION & BEARING REPLACEMENT
See Figures 24 and 25
Connecting rod side clearance and crankshaft bearing inspection/replacement should be performed while the rods are still installed in the engine. Determine the clearance between the connecting rod sides and the crankshaft using a feeler gauge. If clearance is below the minimum, check with a machinist about machining the rod to provide adequate clearance or replace the rod. If clearance is excessive, substitute an unworn rod and recheck; if clearance is still outside specifications, the crankshaft must be welded and reground, or replaced.
To check connecting rod bearing clearances, remove the rod bearing caps one at a time. Using a clean, dry shop rag, thoroughly clean all oil from the crank journal and bearing insert in the cap.
The Plastigage® gauging material is soluble in oil; any oil on the journal or bearing could result in an incorrect reading.
Place a strip of Plastigage® along the full length of the bearing insert (along the crank journal if the engine is out of the truck and inverted). Reinstall the cap and tighten to specifications listed in the Torque Specifications chart.
Remove the rod cap and determine the bearing clearance by comparing the width of the now flattened Plastigage® to the scale on the Plastigage® envelope. Journal taper is determined by comparing the width of the Plastigage® strip near its ends. Rotate the crankshaft 90° and retest, to determine journal eccentricity.
Do not rotate the crankshaft with the Plastigage® installed.
If the bearing insert and crank journal appear intact and are within tolerances, no further service is required and the bearing caps can be reinstalled (remove Plastigage® before installation). If clearances are not within tolerances, the bearing inserts in both the connecting rod and rod cap must be replaced with undersize inserts, and/or the crankshaft must be reground.
To install the bearing insert halves, press them into the bearing caps and connecting rods. Make sure the tab in each insert fits into the notch in each rod and cap. Lube the face of each insert with engine oil prior to installing each rod into the engine.
The connecting rods can be further inspected when they are removed from the engine and separated from their pistons. Rod alignment (straightness and squareness) must be checked by a machinist, as the rod must be set in a special fixture. Many machine shops also perform a crack checking service, a process that shows up any tiny cracks in the metal.
See Figures 26 and 27
- Apply a light coating of engine oil to the pistons, rings, and outer ends of the wrist pins (piston pins).
- Examine the piston to insure that it has been assembled with its parts positioned correctly. Be sure that the ring gaps are not pointed toward the thrust face of the piston and that the gaps are not aligned.
- 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 cylinder.
It is important that the pistons, rods, bearing, etc., be returned to the same cylinder bore from which they were removed.
- Remove the protective rubber hoses. Make certain the connecting rod and cap have the bearings correctly installed. Fit the cap to the rod bolts; tighten them to the torque figures given in the Torque Specifications chart.
Be sure that the mating marks on the connecting rods and rod bearing caps are aligned.
- The rest of the removal procedure is performed in the reverse order of installation.