Mitsubishi Pajero Sport (Montero Sport) 2.5 DI-D 4D56 (2014): Installing the No. 1 Cylinder Piston

Part numbers are from the manufacturer's original catalogue. Check them against your VIN before ordering.

• Socket set and ratchet
• torque wrench (up to 200 N·m (148 lb-ft))
• angle gauge for angle tightening
• piston ring compressor
• bore gauge and micrometer
• feeler gauge
• dial indicator with stand
• plastic drift
• clean rags
• engine oil for lubrication

1. Drain the engine oil and coolant, and disconnect the negative battery terminal. Remove the cylinder head, oil pan and oil pickup tube. On the more powerful 178 hp versions, removal of the front timing drive may be required: follow the marks during removal and then set the shafts to the marks during assembly.
2. Check by hand whether there is a wear ridge at the top of the cylinder. If there is, remove the carbon deposits from the upper part of the cylinder (with a ridge reamer or scraper), otherwise the rings will break when the piston is pushed out.
3. Check the cylinder with a bore gauge: out-of-round and taper must be within tolerance (check the manufacturer's service manual). If wear is significant, the cylinder will need to be bored and an oversize piston used.
4. Inspect the new piston: select it to match the cylinder diameter and check the piston-to-cylinder clearance against the service manual. Make sure the pin and the connecting rod bushing fit each other and that the small end of the connecting rod is undamaged.
5. Install the rings on the piston. The order from bottom to top is: oil control ring (expander and two steel rails), second compression ring, top ring. Point the "TOP" marking or code on the ring upward. Check the end gap of each ring in the cylinder (in the unworn lower part of the cylinder, pushing the ring down with the piston) and the ring side clearance in the groove.
6. Stagger the ring gaps evenly around the piston, about 120° apart. Do not place the gaps over the piston pin axis or line them up with each other. Lubricate the piston, rings and cylinder wall with clean engine oil.
7. Position the crankshaft so that the No. 1 cylinder journal is at bottom dead center (BDC). This makes installation easier and protects the journal from scratches. Put protective sleeves or pieces of hose over the connecting rod bolts.
8. Determine the piston orientation: the arrow or mark on the piston crown must point forward, toward the timing drive (the crankshaft pulley). The combustion bowl in the crown is asymmetrical, and incorrect installation will cause damage at startup. Orient the mark on the connecting rod and rod cap (if present) as specified in the service manual.
9. Fit the ring compressor over the piston and tighten it until the rings are compressed. Rest the compressor against the block deck and carefully press the piston into the cylinder with a wooden hammer handle, without striking it. If you feel resistance, stop: a ring has most likely slipped out of the compressor.
10. Install the upper bearing shell in the connecting rod and the lower shell in the cap, after first cleaning the seats with a degreased rag. Install the shells dry on the seats and oil only the working surface. Pull the rod onto the journal and fit the cap, matching the marks.
11. Tighten the new connecting rod bolts in two or three stages using the torque and angle specified in the service manual for the 4D56 (typically a torque of about 30-40 N·m (22-30 lb-ft) followed by an additional angle; verify the exact values before tightening). Rotate the crankshaft: it should turn freely without binding.
12. Check the connecting rod side clearance on the journal with a feeler gauge. It must be within the service manual tolerance.
13. Measure the piston protrusion above the block deck with a dial indicator at TDC. Measure at two points (along and across the engine axis) for each piston and take the largest value. Use it to select the cylinder head gasket thickness (indicated by notches on the gasket edge): refer to the manufacturer's service manual for the range values.
14. Clean the block and cylinder head surfaces of any remaining old gasket material (without scratching them), blow out the cylinder head bolt holes and remove any oil and coolant from them.
15. Reassemble in reverse order: oil pickup tube with a new gasket, oil pan with sealant, and the cylinder head with a new gasket of the correct thickness and new bolts, tightened in sequence from the center outward, in several stages with the angle tightening specified in the service manual.
16. Set the camshafts to the marks, install the belt or chain, and check the marks after turning the crankshaft by hand through two full revolutions. Fill with oil and coolant.
17. Before starting, crank the engine with the starter for 10-15 seconds without fuel delivery (remove the pump fuse or unplug the connector) to build oil pressure. Then start the engine, check for leaks and knocking, bring the fluids to the proper level, and retighten the cylinder head if the service manual requires it.

• Piston installation on a diesel engine is very sensitive to clearances and protrusion: a mistake in choosing the head gasket or in piston orientation can cause the valves or piston to hit the head and destroy the engine
• If you have no experience with a bore gauge and dial indicator, or lack the proper equipment, have the assembly done by a specialized engine shop
• Do not reuse fasteners marked as single-use