Peugeot 205 Manual
Piston/connecting rod assembly - removal and inspectionEngine removal and overhaul procedures / Piston/connecting rod assembly - removal and inspection
XV, XW and XY series engines 1 With the cylinder head removed, unscrew and remove the bolts which hold the crankcase half sections together. Split the crankcase and keep the main bearing shells with their crankcase web recesses if the shells are to be used again (see illustration).
7.1 Undo the bolts and split the crankcase half sections - XV, XW and XY series engines
2 Remove the crankshaft oil seal.
3 Mark the rim of the cylinder liners in respect of their position and orientation in the block.
Note that No 1 cylinder liner is at the transmission (flywheel) end of the engine.
4 Mark the big-end caps and the connecting rods so that they can be refitted in their original sequence and the correct way round.
A centre punch or hacksaw blade is useful for this purpose.
5 Unscrew the big-end nuts and remove the caps (see illustration). If the bearing shells are to be used again, keep them taped to their respective cap.
7.5 Remove the big-end bearing caps
6 Using a hammer handle, push the piston up through the bore, and remove it from the top of the cylinder liner. Recover the bearing shell, and tape it to the connecting rod for safekeeping.
7 Loosely refit the big-end cap to the connecting rod, and secure with the nuts - this will help to keep the components in their correct order.
XU and TU series engines 8 Remove the cylinder head, sump and oil pump as described in Part B or C of this Chapter (as applicable).
9 Using a hammer and centre-punch, paint or similar, mark each connecting rod and bigend bearing cap with its respective cylinder number on the flat machined surface provided; if the engine has been dismantled before, note carefully any identifying marks made previously (see illustration).
7.9 Marks made on connecting rod and bearing cap - XU and TU series engines
Note that No 1 cylinder is at the transmission (flywheel) end of the engine.
10 Turn the crankshaft to bring pistons 1 and 4 to BDC (bottom dead centre).
11 Unscrew the nuts from No 1 piston bigend bearing cap. Take off the cap, and recover the bottom half bearing shell (see illustration). If the bearing shells are to be reused, tape the cap and the shell together.
7.11 Removing a big-end bearing cap and shell
12 To prevent the possibility of damage to the crankshaft bearing journals, tape over the connecting rod stud threads.
13 Using a hammer handle, push the piston up through the bore, and remove it from the top of the cylinder block/liner. Recover the bearing shell, and tape it to the connecting rod for safe-keeping.
14 Loosely refit the big-end cap to the connecting rod, and secure with the nuts - this will help to keep the components in their correct order.
15 Remove No 4 piston assembly in the same way.
16 Turn the crankshaft through 180° to bring pistons 2 and 3 to BDC (bottom dead centre), and remove them in the same way.
17 Before the inspection process can begin, the piston/connecting rod assemblies must be cleaned, and the original piston rings removed from the pistons.
18 Carefully expand the old rings over the top of the pistons. The use of two or three old feeler blades will be helpful in preventing the rings dropping into empty grooves (see illustration).
7.18 Using old feeler blades to assist removal of the piston rings
Be careful not to scratch the piston with the ends of the ring. The rings are brittle, and will snap if they are spread too far.
They are also very sharp - protect your hands and fingers. Note that the third ring may incorporate an expander. Always remove the rings from the top of the piston. Keep each set of rings with its piston if the old rings are to be re-used.
19 Scrape away all traces of carbon from the top of the piston. A hand-held wire brush (or a piece of fine emery cloth) can be used, once the majority of the deposits have been scraped away.
20 Remove the carbon from the ring grooves in the piston, using an old ring. Break the ring in half to do this (be careful not to cut your fingers - piston rings are sharp). Be careful to remove only the carbon deposits - do not remove any metal, and do not nick or scratch the sides of the ring grooves.
21 Once the deposits have been removed, clean the piston/connecting rod assembly with paraffin or a suitable solvent, and dry thoroughly. Make sure that the oil return holes in the ring grooves are clear.
22 If the pistons and cylinder liners/bores are not damaged or worn excessively, the original pistons can be refitted. Normal piston wear shows up as even vertical wear on the piston thrust surfaces, and slight looseness of the top ring in its groove. New piston rings should always be used when the engine is reassembled.
23 Carefully inspect each piston for cracks around the skirt, around the gudgeon pin holes, and at the piston ring “lands” (between the ring grooves).
24 Look for scoring and scuffing on the piston skirt, holes in the piston crown, and burned areas at the edge of the crown. If the skirt is scored or scuffed, the engine may have been suffering from overheating, and/or abnormal combustion which caused excessively high operating temperatures. The cooling and lubrication systems should be checked thoroughly. Scorch marks on the sides of the pistons show that blow-by has occurred. A hole in the piston crown, or burned areas at the edge of the piston crown, indicates that abnormal combustion (preignition, knocking, or detonation) has been occurring. If any of the above problems exist, the causes must be investigated and corrected, or the damage will occur again.
The causes may include incorrect ignition timing, or a carburettor or fuel injection system fault.
25 Corrosion of the piston, in the form of pitting, indicates that coolant has been leaking into the combustion chamber and/or the crankcase. Again, the cause must be corrected, or the problem may persist in the rebuilt engine.
26 On aluminium-block engines with wet liners, it is not possible to renew the pistons separately; pistons are only supplied with piston rings and a liner, as part of a matched assembly (see Section 9). On cast-iron block engines, pistons can be purchased from a Peugeot dealer.
27 Examine each connecting rod carefully for signs of damage, such as cracks around the big-end and small-end bearings. Check that the rod is not bent or distorted. Damage is highly unlikely, unless the engine has been seized or badly overheated. Detailed checking of the connecting rod assembly can only be carried out by a Peugeot dealer or engine repair specialist with the necessary equipment.
28 On XU series engines, due to the tightening procedure for the connecting rod big-end cap retaining nuts, it is highly recommended that the big-end cap nuts and bolts are renewed as a complete set prior to refitting.
29 On all engines, the gudgeon pins are an interference fit in the connecting rod smallend bearing. Therefore, piston and/or connecting rod renewal should be entrusted to a Peugeot dealer or engine repair specialist, who will have the necessary tooling to remove and install the gudgeon pins.