Pistons and connecting rods — removal and installation Ford F150
Removal
Note: Prior to removing the piston/connecting rod assemblies, remove the cylinder head and oil pan (see V6 engines or V8 engines).
Before you try to remove the pistons, use a ridge reamer to remove the raised material (ridge) from the top of the cylinders
1. Use your fingernail to feel if a ridge has formed at the upper limit of ring travel (about 1/4-inch down from the top of each cylinder). If carbon deposits or cylinder wear have produced ridges, they must be completely removed with a special tool (see illustration). Follow the manufacturer’s instructions provided with the tool. Failure to remove the ridges before attempting to remove the piston/connecting rod assemblies may result in piston breakage.
2. After the cylinder ridges have been removed, turn the engine so the crankshaft is facing up.
Note: To access the main bearing caps and piston rod caps, remove the engine block skirt stiffener. On V6 engines remove the main bearing cap support brace (see Crankshaft – removal and installation).
Checking the connecting rod endplay (side clearance)
3. Before the main bearing cap assembly and connecting rods are removed, check the connecting rod endplay with feeler gauges. Slide them between the first connecting rod and the crankshaft throw until the play is removed (see illustration). Repeat this procedure for each connecting rod. The endplay is equal to the thickness of the feeler gauge(s).
Note: Check with an automotive machine shop for the endplay service limit (a typical endplay limit should measure between 0.005 to 0.015 inch [0.127 to 0.381 mm]). If the play exceeds the service limit, new connecting rods will be required. If new rods (or a new crankshaft) are installed, the endplay may fall under the minimum allowable. If it does, the rods will have to be machined to restore it. If necessary, consult an automotive machine shop for advice.
i.4 If the connecting rods and caps are not marked, mark the caps to the rods by cylinder number (for example, this would be the No. 4 connecting rod)
4. Check the connecting rods and caps for identification marks. If they aren’t plainly marked, use paint or marker to clearly identify each rod and cap (1, 2, 3, etc., depending on the cylinder they’re associated with) (see illustration).
5. Remove the connecting rod cap bolts evenly.
Note: Obtain new bolts for final installation, but save the old bolts for the oil clearance check that will be performed later.
6. Remove the number one connecting rod cap and bearing insert. Don’t drop the bearing insert out of the cap.
7. Remove the bearing insert and push the connecting rod/piston assembly out through the top of the engine. Use a wooden or plastic hammer handle to push on the upper bearing surface in the connecting rod. If resistance is felt, double-check to make sure that all of the ridge was removed from the cylinder.
8. Repeat the procedure for the remaining cylinders.
9. After removal, reassemble the connecting rod caps and bearing inserts in their respective connecting rods and install the cap bolts finger-tight. Leaving the old bearing inserts in place until reassembly will help prevent the connecting rod bearing surfaces from being accidentally nicked or gouged.
10. The pistons and connecting rods are now ready for inspection and overhaul at an automotive machine shop.
Piston ring installation
11. Before installing the new piston rings, the ring end gaps must be checked. It’s assumed that the piston ring side clearance has boen checked and verified correct.
12. Lay out the piston/connecting rod assemblies and the new ring sets so the ring sets will be matched with the same piston and cylinder during the end gap measurement and engine assembly.
Install the piston ring into the cylinder then push it down into position using a piston so the ring will be square in the cylinder
13. Insert the top (number one) ring into the first cylinder and square it up with the cylinder walls by pushing it in with the top of the piston (see illustration). The ring should be near the bottom of the cylinder, at the lower limit of ring travel.
With the ring square in the cylinder, measure the ring end gap with a feeler gauge
14. To measure the end gap, slip feeler gauges between the ends of the ring until a gauge equal to the gap width is found (see illustration). The feeler gauge should slide between the ring ends with a slight amount of drag. A typical ring gap should fall between 0.010 and 0.020 inch [0.25 to 0.50 mm] for compression rings and up to 0.030 inch [0.76 mm] for the oil ring steel rails. If the gap is larger or smaller than specified, double-check to make sure you have the correct rings before proceeding.
If the ring end gap is too small, clamp a file in a vise as shown and file the piston ring ends — be sure to remove all raised material
15. If the gap is too small, it must be enlarged or the ring ends may come in contact with each other during engine operation, which can cause serious damage to the engine. If necessary, increase the end gaps by filing the ring ends very carefully with a fine file. Mount the file in a vise equipped with soft jaws, slip the ring over the file with the ends contacting the file face and slowly move the ring to remove material from the ends. When performing this operation, file only by pushing the ring from the outside end of the file towards the vise (see illustration).
16. Excess end gap isn’t critical unless it’s greater than 0.040 inch (1.01 mm). Again, double-check to make sure you have the correct ring type.
17. Repeat the procedure for each ring that will be installed in the first cylinder and for each ring in the remaining cylinders. Remember to keep rings, pistons and cylinders matched up.
18. Once the ring end gaps have been checked/corrected, the rings can be installed on the pistons.
Note: Don’t use a piston ring installation tool on the oil ring side rails, as they may be damaged. Instead, place one end of the side rail into the groove between the spacer/expander and the ring land, hold it firmly in place and slide a finger around the piston while pushing the rail into the groove. Finally, install the lower side rail.
Installing the oil ring spacer in the piston oil ring groove
DO NOT use a piston ring installation tool when installing the oil control side rails (oil rings)
19. The oil control ring (lowest one on the piston) is usually installed first. It’s composed of three separate components. Slip the pacer/expander into the groove (see illustration). If an anti-rotation tang is used, make sure it’s inserted into the drilled hole in the ring groove. Next, install the upper side rail in the same manner (see illustration).
Caution: Don’t use a piston ring installation tool on the oil ring side rails, as they may be damaged. Instead, place one end of the side rail into the groove between the spacer/expander and the ring land, hold it firmly in place and slide a finger around the piston while pushing the rail into the groove. Finally, install the lower side rail.
20. After the three oil ring components have been installed, check to make sure that both the upper and lower side rails can be rotated smoothly inside the ring grooves.
21. The number two (middle) ring is installed next. It’s usually stamped with a mark which must face up, toward the top of the piston. Do not mix up the top and middle rings, as they have different cross-sections.
Note: Always follow the instructions printed on the ring package or box — different manufacturers may require different approaches.
Use a piston ring installation tool to install the number 2 and the number 1 (top) compression rings — be sure the directional mark on the piston ring(s) is facing toward the top of the piston
22. Use a piston ring installation tool and make sure the identification mark is facing the top of the piston, then slip the ring into the middle groove on the piston (see illustration). Don’t expand the ring any more than necessary to slide it over the piston.
23. Install the number one (top) ring in the same manner. Make sure the mark is facing up. Be careful not to confuse the number one and number two rings.
24. Repeat the procedure for the remaining pistons and rings.
Installation
25. Before installing the piston/connecting rod assemblies, the cylinder walls must be perfectly clean, the top edge of each cylinder bore must be chamfered, and the crankshaft must be in place.
26. Remove the cap from the end of the number one connecting rod (refer to the marks made during removal). Remove the original bearing inserts and wipe the bearing surfaces of the connecting rod and cap with a clean, lint-free cloth. They must be kept spotlessly clean.
Connecting rod bearing oil clearance check
27. Clean the back side of the new upper bearing insert, then lay it in place in the connecting rod.
28. Make sure the tab on the bearing fits into the recess in the rod. Don’t hammer the bearing insert into place and be very careful not to nick or gouge the bearing face. Don’t lubricate the bearing at this time.
29. Clean the back side of the other bearing insert and install it in the rod cap. Again, make sure the tab on the bearing fits into the recess in the cap, and don’t apply any lubricant. It’s critically important that the mating surfaces of the bearing and connecting rod are perfectly clean and oil free when they’re assembled.
i.30a Position the piston ring end gaps as shown here before installing the piston/connecting rod assemblies into the engine — V6 engines
i.30b Position the piston ring end gaps as shown here before installing the piston/connecting rod assemblies into the engine — V8 engines
30. Position the piston ring gaps at intervals around the piston as shown (see illustrations).
31. Lubricate the piston and rings with clean engine oil and attach a piston ring compressor to the piston. Leave the skirt protruding about 1/4-inch to guide the piston into the cylinder. The rings must be compressed until they’re flush with the piston.
32. Rotate the crankshaft until the number one connecting rod journal is at BDC (bottom dead center) and apply a liberal coat of engine oil to the cylinder walls.
33. With the weight designation mark on top of the piston facing the front (timing chain end) of the engine, gently insert the piston/ connecting rod assembly into the number one cylinder bore and rest the bottom edge of the ring compressor on the engine block. Install the pistons with the cavity mark(s) facing toward the timing chain.
34. Tap the top edge of the ring compressor to make sure it’s contacting the block around its entire circumference.
Use a plastic or wooden hammer handle to push the piston into the cylinder
35. Gently tap on the top of the piston with the end of a wooden or plastic hammer handle (see illustration) while guiding the end of the connecting rod into place on the crankshaft journal. Caution: Do not force the piston into the cylinder — you might break a ring and/or the piston. Note: The piston rings may try to pop out of the ring compressor just before entering the cylinder bore, so keep some downward pressure on the ring compressor. Work slowly, and if any resistance is felt as the piston enters the cylinder, stop immediately. Find out what’s hanging up and fix it before proceeding.
36. Once the piston/connecting rod assembly is installed, the connecting rod bearing oil clearance must be checked before the rod cap is permanently installed.
Place Plastigage on each connecting rod bearing journal parallel to the crankshaft centerline
37. Cut a piece of the appropriate size Plastigage slightly shorter than the width of the connecting rod bearing and lay it in place on the number one connecting rod journal, parallel with the journal axis (see illustration).
38. Clean the connecting rod cap bearing face and install the rod cap. Make sure the mating mark on the cap is on the same side as the mark on the connecting rod (see illustration 4).
39. Install the old rod bolts, at this time, and tighten them to the torque listed in this Chapter’s Specifications.
Note: Use a thin-wall socket to avoid erroneous torque readings that can result if the socket is wedged between the rod cap and the bolt. If the socket tends to wedge itself between the fastener and the cap, lift up on it slightly until it no longer contacts the cap. DO NOT rotate the crankshaft at any time during this operation.
40. Remove the fasteners and detach the rod cap, being very careful not to disturb the Plastigage. Discard the cap bolts at this time as they cannot be reused.
Note: You MUST use new connecting rod bolts.
Use the scale on the Plastigage package to determine the bearing oil clearance — be sure to measure the widest part of the Plastigage and use the correct scale; it comes with both standard and metric scales
41. Compare the width of the crushed Plastigage to the scale printed on the Plastigage envelope to obtain the oil clearance (see illustration). The connecting rod oil clearance is usually about 0.001 to 0.002 inch. Consult an automotive machine shop for the clearance specified for the rod bearings on your engine.
42. If the clearance is not as specified, the bearing inserts may be the wrong size (which means different ones will be required). Before deciding that different inserts are needed, make sure that no dirt or oil was between the bearing inserts and the connecting rod or cap when the clearance was measured.
Note: Recheck the journal diameter. If the Plastigage was wider at one end than the other, the journal may be tapered. If the clearance still exceeds the limit specified, the bearing will have to be replaced with an undersize bearing.
Caution: When installing a new crankshaft always use a standard size bearing.
Final installation
43. Carefully scrape all traces of the Plastigage material off the rod journal and/or bearing face. Be very careful not to scratch the bearing — use your fingernail or the edge of a plastic card.
44. Make sure the bearing faces are perfectly clean, then apply a uniform layer of clean moly-base grease or engine assembly lube to both of them. You’ll have to push the piston into the cylinder to expose the face of the bearing insert in the connecting rod.
45. Slide the connecting rod back into place on the journal, install the rod cap, install the new bolts and tighten them to the torque listed in this Chapter’s Specifications.
Caution: Install new connecting rod cap bolts. Do NOT reuse old bolts — they have stretched and cannot be reused .
46. Repeat the entire procedure for the remaining pistons/connecting rods.
47. The important points to remember are:
- Keep the back sides of the bearing inserts and the insides of the connecting rods and caps perfectly clean when assembling them.
- Make sure you have the correct piston/ rod assembly for each cylinder.
- The mark on the piston must face the front (timing chain end) of the engine.
- Lubricate the cylinder walls liberally with clean oil.
- Lubricate the bearing faces when installing the rod caps after the oil clearance has been checked.
48. After all the piston/connecting rod assemblies have been correctly installed, rotate the crankshaft a number of times by hand to check for any obvious binding.
49. As a final step, check the connecting rod endplay, as described in Step 3. If it was correct before disassembly and the original crankshaft and rods were reinstalled, it should still be correct.
Note: If new rods or a new crankshaft were installed, the endplay may be inadequate. If so, the rods will have to be removed and taken to an automotive machine shop for resizing.
50. On 2.7L engines, install the engine block skirt stiffener and, on 3.3L and 3.5L engines, install the main bearing cap support brace (see Crankshaft – removal and installation).