Note: A special reference piston is required for checking piston protrusion. The following paragraphs are meant as a guide for use with this too/. If you do not have this tool, the check should be done by a Peugeot dealer.
1. Before refitting the cylinder head, measure piston crown protrusion in relation to the upper face of the cylinder block, in order to determine the correct piston height size group. Proceeds as follows:
2. Fit the No 4 cylinder connecting rod to the reference piston. The reference piston does not have grooves for the gudgeon pin circlips.
3. Place a new bearing shell on the big-end bearing and slide the piston/connecting rod assembly into No 4 cylinder.
4. With a new bearing shell in place, refit the bearing cap. Tighten the cap retaining nuts uniformly and progressively to the specified torque wrench setting.
5. In order that the crankshaft can be turned, insert the timing belt sprocket retaining bolt temporarily.
6. Mount a dial gauge and stand on the cylinder head gasket surface of the cylinder block so that the probe touches the central boss of the reference piston.
7. Turn the crankshaft to bring the reference piston exactly to TDC, then set the dial gauge to zero.
8. Move the dial gauge and stand sideways so that the probe touches the cylinder block gasket surface, and note down the degree of piston protrusion displayed on the dial gauge.
9. Proceed as above for the three other cylinders, using the corresponding connecting rods.
10. Choose the correct piston height size group from the table below. Note that the groups are identified by the letters stamped on their crown.
| Reference piston protrusion (mm) | Piston group-original fitment |
| Above 2.5 | Non standard: check dimensions of individual components |
| 2.5 to 2.4 | A |
| 2.43 to 2.33 | B |
| 2.36 to 2.26 | c |
| Below 2.26 | Non standard: check dimensions of individual components |
| Reference piston protrusion (mm) | Piston group-repair components |
| Above 2.3 | Non standard: check dimensions of individual components |
| 2.3 to 2.2 | X |
| 2.23 to 2.13 | Y |
| 2.16 to 2.06 | Z |
| Below 2.06 | Non standard: check dimensions of individual components |
11. After the height size group of each piston has been determined, fit the piston rings and connecting rods, and slide the piston/connecting rod assemblies into the cylinders (see Section 16).