See Figures 1 through 8
- Drain the cooling system and the crankcase.
- Remove the cylinder head.
- Remove the oil pan, the oil pump inlet tube and the oil pump.
- Turn the crankshaft until the piston to be removed is at the bottom of its travel and place a cloth on the piston head to collect filings. Using a ridge reaming tool, remove any ridge of carbon or any other deposit from the upper cylinder walls where piston travel ends. Do not cut into the piston ring travel area more than 1 / 32 inch; (0.8mm) while removing the ridge.
- Mark all of the connecting rod caps so that they can be reinstalled in the original positions from which they are removed and remove the connecting rod bearing cap. Also identify the piston assemblies as they, too, must be reinstalled in the same cylinder from which removed.
- With the bearing caps removed, the connecting rod bearing bolts are potentially damaging to the cylinder walls during removal. To guard against cylinder wall damage, install 4 inch; (101.6mm) or 5 inch; (127mm) lengths of 3 / 8 inch; (9.5mm) rubber tubing onto the connecting rod bolts. These will also protect the crankshaft journal from scratches when the connecting rod is installed, and will serve as a guide for the rod.
- Squirt some clean engine oil into each cylinder before removing the pistons. Using a wooden hammer handle, push the connecting rod and piston assembly out of the top of the cylinder (pushing from the bottom of the rod). Be careful to avoid damaging both the crank journal and the cylinder wall when removing the rod and piston assembly.
- Drain the cooling system and the crankcase.
- Remove the intake manifold.
- Remove the cylinder heads.
- Remove the oil pan.
- Remove the oil pump.
- Turn the crankshaft until the piston to be removed is at the bottom of its travel, then place a cloth on the piston head to collect filings.
- Remove any ridge of deposits at the end of the piston travel from the upper cylinder bore, using a ridge reaming tool. Do not cut into the piston ring travel area more than 1 / 32 inch; (0.8mm) when removing the ridge.
- Make sure that all of the connecting rod bearing caps can be identified, so they will be reinstalled in their original positions.
- Turn the crankshaft until the connecting rod that is to be removed is at the bottom of its stroke and remove the connecting rod nuts and bearing cap.
- With the bearing caps removed, the connecting rod bearing bolts are potentially damaging to the cylinder walls during removal. To guard against cylinder wall damage, install four or five inch lengths of 3 / 8 inch; (0.8mm) rubber tubing onto the connecting rod bolts. These will also protect the crankshaft journal from scratches when the connecting rod is installed, and will serve as a guide for the rod.
- Squirt some clean engine oil into each cylinder before removing the piston assemblies. Using a wooden hammer handle, push the connecting rod and piston assembly out of the top of the cylinder (pushing from the bottom of the rod). Be careful to avoid damaging both the crank journal and the cylinder wall when removing the rod and piston assembly.
- Remove the bearing inserts from the connecting rod and cap if the bearings are to be replace, and place the cap onto the piston/rod assembly from which it was removed.
The connecting rod and bearing caps are numbered from 1 to 4 in the right bank and from 5 to 8 in in the left bank, beginning at the front of the engine. The numbers on the rod and cap must be on the same side when they are installed in the cylinder bore. Also, the largest chamfer at the bearing end of the rod should be positioned toward the crank pin thrust face of the crankshaft and the notch in the head of the piston faces toward the front of the engine.
PISTON AND ROD DISASSEMBLY
See Figures 9, 10 and 11
All of the Ford gasoline engines covered in this guide utilize pressed-in wrist pins, which can only be removed by an arbor press. The diesel pistons are removed in the same way, only the pistons are heated before the wrist pins are pressed out. On both gasoline and diesel engines, the piston/connecting rod assemblies should be taken to an engine specialist or qualified machinist for piston removal and installation.
A piston ring expander is necessary for removing the piston rings without damaging them; any other method (screwdriver blades, pliers, etc.) usually results in the rings being bent, scratched or distorted, or the piston itself being damaged. When the rings are removed, clean the ring grooves using an appropriate ring groove cleaning tool, using care not to cut too deeply.
CLEANING AND INSPECTION
See Figures 12, 13 and 14
Thoroughly clean all carbon and varnish from the piston with solvent.
The piston should also be checked in relation to the cylinder diameter. Using a telescoping gauge and micrometer, or a dial gauge, measure the cylinder bore diameter perpendicular (90 degrees) to the piston pin, 2 1 / 2 inch; (64mm) below the cylinder block deck (surface where the block mates with the heads). Then, with the micrometer, measure the piston, perpendicular to its wrist pin on the skirt. the difference between the two measurements is the piston clearance. If the clearance is within specifications or slightly below (after the cylinders have been bored or hones), finish honing is all that is necessary. If the clearance is excessive, try to obtain a slightly larger piston to bring clearance to within specifications. If this is not possible, obtain the first oversize piston and hone (or if necessary, bore) the cylinder to size. Generally, if the cylinder bore is tapered 0.005 inch; (0.127mm) or more or is out-of-round 0.003 inch; (0.076mm) or more, it is advisable to rebore for the
smallest possible oversize piston and rings.
After measuring, mark pistons with a felt tip pen for reference and for assembly.
Cylinder honing and/or boring should be performed by a reputable, professional mechanic with the proper equipment. In some cases, clean-up honing can be done with the cylinder block in the car, but most excessive honing and all cylinder boring must be done with the block stripped and removed from the truck. Before honing the diesel cylinders, the piston oil cooling jets must be removed. This procedure should be handled by a diesel specialist, as special tools are needed. Jets cannot be reused; new jets should be fitted.Measuring the Old Pistons
See Figure 15
Check used piston-to-cylinder bore clearance as follows:
- Measure the cylinder bore diameter with a telescope gauge.
- Measure the piston diameter. When measuring the pistons for size or taper, measurements must be made with the piston pin removed.
- Subtract the piston diameter from the cylinder bore diameter to determine piston-to-bore clearance.
- Compare the piston-to-bore clearances obtained with those clearances recommended. Determine if the piston-to-bore clearance is in the acceptable range.
- When measuring taper, the largest reading must be at the bottom of the skirt.
- If the used piston is not acceptable, check the service piston size and determine if a new piston can be selected. (Service pistons are available in standard, high limit and standard oversize.
- If the cylinder bore must be reconditioned, measure the new piston diameter, then hone the cylinder bore to obtain the preferred clearance.
- Select a new piston and mark the piston to identify the cylinder for which it was fitted. (On some vehicles, oversize pistons may be found. These pistons will be 0.010 inch; (0.254mm) oversize).
See Figures 16 and 17
- When cylinders are being honed, follow the manufacturer's recommendations for the use of the hone.
- Occasionally, during the honing operation, the cylinder bore should be thoroughly cleaned and checked for correct fit with the selected piston.
- When finish-honing a cylinder bore, the hone should be moved up and down at a sufficient speed to obtain a very fine uniform surface finish in a cross-hatch pattern of approximately 45-65 degrees included angle. The finish marks should be clean but not sharp, free from imbedded particles and torn or folded metal.
- Permanently mark the piston for the cylinder to which it has been fitted and proceed to hone the remaining cylinders.
- Thoroughly clean the bores with hot water and detergent. Scrub well with a stiff bristle brush and rinse thoroughly with hot water. It is extremely essential that a good cleaning operation be performed. If any of the abrasive material is allowed to remain in the cylinder bores, it will rapidly wear the new rings and cylinder bores. The bores should be swabbed several times with light engine oil and a clean cloth and then wiped with a clean dry cloth. CYLINDERS SHOULD NOT BE CLEANED WITH KEROSENE OR GASOLINE! Clean the remainder of the cylinder block to remove the excess material spread during the honing operation.
PISTON RING END GAP
See Figure 18
Piston ring end gap should be checked while the rings are removed from the pistons. Incorrect end gap indicates that the wrong size rings are being used; ring breakage could occur.
Compress the piston rings to be used in a cylinder, one at a time, into that cylinder. Squirt clean oil into the cylinder, so that the rings and the top 2 inch; (51mm) of cylinder wall are coated. Using an inverted piston, press the rings approximately 1 inch; (25mm) below the deck of the block (on diesels, measure ring gap clearance with the ring positioned at the bottom of ring travel in the bore). Measure the ring end gap with the feeler gauge, and compare to the Ring Gap chart in this section. Carefully pull the ring out of the cylinder and file the ends squarely with a fine file to obtain the proper clearance.
PISTON RING SIDE CLEARANCE CHECK AND RIND INSTALLATION
See Figures 19, 20 and 21
Check the pistons to see that the ring grooves and oil return holes have been properly cleaned. Slide a piston ring into its groove, and check the side clearance with a feeler gauge. On gasoline engines, make sure you insert the gauge between the ring and its lower land (lower edge of the groove), because any wear that occurs forms a step at the inner portion of the lower land. On diesels, insert the gauge between the ring and the upper land. If the piston grooves have worn to the extent that relatively high steps exist on the lower land, the piston should be replaced, because these will interfere with the operation of the new rings and ring clearance will be excessive. Piston rings are not furnished in oversize widths to compensate for ring groove wear.
Install the rings on the piston, lowest ring first, using a piston ring expander. There is a high risk of breaking or distorting the rings, or scratching the piston, if the rings are installed by hand or other means.
Position the rings on the piston; spacing of the various piston ring gaps is crucial to proper oil retention and even cylinder wear. When installing new rings, refer to the installation diagram furnished with the new parts.
CONNECTING ROD BEARING INSPECTION
Connecting rod bearings for the engines covered in this guide consist of two halves or shells which are interchangeable in the rod and cap. When the shells are placed in position, the ends extend slightly beyond the rod and cap surfaces so that with the rod bolts torqued the shells will be clamped tightly in place to insure positive seating and to prevent turning. A tang holds the shells in place.
The ends of the bearing shells must never be filed flush with the mating surfaces of the rod and cap.
If a rod bearing becomes noisy or is worn so that its clearance on the crank journal is sloppy, a new bearing of the correct undersize must be selected and installed since there is no provision for adjustment.
Inspect the rod bearings while the rod assemblies are out of the engine. If the shells are scored or show flaking, they should be replaced. If they are in good shape, check for proper clearance on the crank journal (see below). Any scoring or ridges on the crank journal means the crankshaft must be reground and fitted with undersized bearings, or replaced.
CHECKING BEARING CLEARANCE AND REPLACING BEARINGS
See Figures 22 and 23
Make sure connecting rods and their caps are kept together, and that the caps are installed in the proper direction.
Replacement bearings are available in standard size, and in undersizes for reground crankshaft. Connecting rod-to-crankshaft bearing clearance is checked using Plastigage® at either the top or bottom of each crank journal. Plastigage® has a range of 0 to 0.003 inch; (0.076mm).
- Remove the rod cap with the bearing shell. Completely clean the bearing shell and the crank journal, and blow any oil from the oil hole in the crankshaft.
The journal surfaces and bearing shells must be completely free of oil, because Plastigage® is soluble in oil.
- Place a strip of Plastigage® lengthwise along the bottom center of the lower bearing shell, then install the cap with shell and torque the bolt or nuts to specification. DO NOT TURN the crankshaft with the Plastigage® installed in the bearing.
- Remove the bearing cap with the shell. The flattened Plastigage® will be found sticking to either the bearing shell or crank journal. Do not remove it yet.
- Use the printed scale on the Plastigage® envelope to measure the flattened material at its widest point. The number within the scale which most closely corresponds to the width of the Plastigage® indicated bearing clearance in thousandths of an inch.
- Check the specifications chart in this section for the desired clearance. It is advisable to install a new bearing if clearance exceeds 0.003 inch; (0.076mm); however, if the bearing is in good condition and is not being checked because of bearing noise, bearing replacement is not necessary.
- If you are installing new bearings, try a standard size, then each undersize in order until one is found that is within the specified limits when checked for clearance with Plastigage®. Each under size has its size stamped on it.
- When the proper size shell is found, clean off the Plastigage® material from the shell, oil the bearing thoroughly, reinstall the cap with its shell and torque the rod bolt nuts to specification.
With the proper bearing selected and the nuts torqued, it should be possible to move the connecting rod back and forth freely on the crank journal as allowed by the specified connecting rod end clearance. If the rod cannot be moved, either the rod bearing is too far undersize or the rod is misaligned.
PISTON AND CONNECTING ROD ASSEMBLY AND INSTALLATION
See Figures 24 through 30
Install the connecting rod to the piston making sure piston installation notches and any marks on the rod are in proper relation to one another. Lubricate the wrist pin with clean engine oil and install the pin into the rod and piston assembly by using an arbor press as required. Install the wrist pin snaprings if equipped, and rotate them in their grooves to make sure they are seated. To install the piston and rod assemblies:
- Make sure the connecting rod big bearings (including end cap) are of the correct size and properly installed.
- Fit rubber hoses over the connecting rod bolt to protect the crankshaft journals, as in the Piston Removal procedure. Coat the rod bearings with clean oil.
- Using the proper ring compressor, insert the piston assembly into the cylinder so that the notch in the top of the piston faces the front of the engine on all but the 8-360/390. On these engines, the V-shaped indentation faces inwards (towards the center of the engine. This assumes that the dimple(s) or other markings on the connecting rods are in correct relation to the piston notch(s).
- From beneath the engine, coat each crank journal with clean oil. Pull the connecting rod, with the bearing shell in place, into position against the crank journal.
- Remove the rubber hoses. Install the bearing cap and cap nuts and torque to specification.
When more than one rod and piston assembly is being installed, the connecting rod cap attaching nuts should only be tightened enough to keep each rod in position until all have been installed. This will ease the installation of the remaining piston assemblies.
- Check the clearance between the sides of the connecting rods and the crankshaft using a feeler gauge. Spread the rods slightly with a screwdriver to insert the gauge. If clearance is below the minimum tolerance, the rod may be machined to provide adequate clearance. 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.
- Replace the oil pump if removed, and the oil pan.
- Install the cylinder head(s) and intake manifold.