Peugeot 205 Manual
Cylinder head - dismantling, cleaning, inspection and reassemblyEngine removal and overhaul procedures / Cylinder head - dismantling, cleaning, inspection and reassembly
Note: New and reconditioned cylinder heads are available from the manufacturer, and from engine overhaul specialists. Be aware that some specialist tools are required for the dismantling and inspection procedures, and new components may not be readily available.
It may therefore be more practical and economical for the home mechanic to purchase a reconditioned head, rather than dismantle, inspect and recondition the original head.
1 Remove the cylinder head as described in Part A, B or C of this Chapter (as applicable).
2 If not already done, remove the inlet and exhaust manifolds with reference to the relevant Part of Chapter 4.
3 Remove the camshaft, followers and shims (as applicable) as described in Part A, B or C of this Chapter.
4 Using a valve spring compressor, compress each valve spring in turn until the split collets can be removed. Release the compressor, and lift off the spring retainer, spring and spring seat. Using a pair of pliers, carefully extract the valve stem oil seal from the top of the guide (see illustrations).
6.4a Compress the valve spring with a compressor and remove the split collets . . .
6.4b . . . Release the compressor and remove the spring retainer . . .
6.4c . . . spring . . .
6.4d . . . spring seat and valve stem oil seal
5 If, when the valve spring compressor is screwed down, the spring retainer refuses to free and expose the split collets, gently tap the top of the tool, directly over the retainer, with a light hammer. This will free the retainer.
6 Withdraw the valve through the combustion chamber (see illustration).
6.6 Withdraw the valve through the combustion chamber
7 It is essential that each valve is stored together with its collets, retainer, spring, and spring seat. The valves should also be kept in their correct sequence, unless they are so badly worn that they are to be renewed. If they are going to be kept and used again, place each valve assembly in a labelled polythene bag or similar small container (see illustration).
6.7 Place each valve and its associated components in a labelled polythene bag
Note that No 1 valve is nearest to the transmission (flywheel/driveplate) end of the engine.
8 Thoroughly clean all traces of old gasket material and sealing compound from the cylinder head upper and lower mating surfaces. Use a suitable cleaning agent together with a soft putty knife; do not use a metal scraper or the faces will be damaged.
9 Remove the carbon from the combustion chambers and ports, then clean all traces of oil and other deposits from the cylinder head, paying particular attention to the bearing journals, cam follower bores (where applicable), valve guides and oilways.
10 Wash the head thoroughly with paraffin or a suitable solvent. Take plenty of time and do a thorough job. Be sure to clean all oil holes and galleries very thoroughly, dry the head completely and coat all machined surfaces with light oil.
11 Scrape off any heavy carbon deposits that may have formed on the valves, then use a power-operated wire brush to remove deposits from the valve heads and stems.
Note: Be sure to perform all the following inspection procedures before concluding that the services of an engineering works are required. Make a list of all items that require attention.
12 Inspect the head very carefully for cracks, evidence of coolant leakage, and other damage. If cracks are found, a new cylinder head should be obtained.
13 Use a straight-edge and feeler blade to check that the cylinder head gasket surface is not distorted. If it is, it may be possible to have it machined. Seek the advice of a Peugeot dealer or engine overhaul specialist if distortion is suspected.
14 Examine the valve seats in each of the combustion chambers. If they are severely pitted, cracked, or burned, they will need to be renewed or re-cut by an engine overhaul specialist. If they are only slightly pitted, this can be removed by grinding-in the valve heads and seats with fine valve-grinding compound, as described below.
15 Check the valve guides for wear by inserting the relevant valve, and checking for side-to-side motion of the valve. A very small amount of movement is acceptable. If the movement seems excessive, remove the valve.
Measure the valve stem diameter (see below), and renew the valve if it is worn. If the valve stem is not worn, the wear must be in the valve guide, and the guide must be renewed. The renewal of valve guides is best carried out by a Peugeot dealer or engine overhaul specialist, who will have the necessary tools available.
16 If renewing the valve guides, the valve seats should be re-cut or re-ground only after the guides have been fitted.
17 Examine the head of each valve for pitting, burning, cracks, and general wear. Check the valve stem for scoring and wear ridges. Rotate the valve, and check for any obvious indication that it is bent. Look for pits or excessive wear on the tip of each valve stem. Renew any valve that shows any such signs of wear or damage.
18 If the valve appears satisfactory at this stage, measure the valve stem diameter at several points using a micrometer (see illustration).
6.18 Measuring the valve stem diameter
Any significant difference in the readings obtained indicates wear of the valve stem. Should any of these conditions be apparent, the valve(s) must be renewed.
19 If the valves are in satisfactory condition, they should be ground (lapped) into their respective seats, to ensure a smooth, gastight seal. If the seat is only lightly pitted, or if it has been re-cut, fine grinding compound only should be used to produce the required finish. Coarse valve-grinding compound should not be used, unless a seat is badly burned or deeply pitted. If this is the case, the cylinder head and valves should be inspected by an expert, to decide whether seat recutting, or even the renewal of the valve or seat insert (where possible) is required.
20 Valve grinding is carried out as follows.
Place the cylinder head upside-down on a bench.
21 Smear a trace of (the appropriate grade of) valve-grinding compound on the seat face, and press a suction grinding tool onto the valve head (see illustration).
6.21 Grinding-in a valve
With a semirotary action, grind the valve head to its seat, lifting the valve occasionally to redistribute the grinding compound. A light spring placed under the valve head will greatly ease this operation.
22 If coarse grinding compound is being used, work only until a dull, matt even surface is produced on both the valve seat and the valve, then wipe off the used compound, and repeat the process with fine compound. When a smooth unbroken ring of light grey matt finish is produced on both the valve and seat, the grinding operation is complete. Do not grind-in the valves any further than absolutely necessary, or the seat will be prematurely sunk into the cylinder head.
23 When all the valves have been ground-in, carefully wash off all traces of grinding compound using paraffin or a suitable solvent, before reassembling the cylinder head.
24 Examine the valve springs for signs of damage and discoloration. No minimum free length is specified by Peugeot, so the only way of judging valve spring wear is by comparison with a new component.
25 Stand each spring on a flat surface, and check it for squareness. If any of the springs are damaged, distorted or have lost their tension, obtain a complete new set of springs.
It is normal to renew the valve springs as a matter of course if a major overhaul is being carried out.
26 Renew the valve stem oil seals regardless of their apparent condition.
27 Lubricate the stems of the valves, and insert the valves into their original locations (see illustration). If new valves are being fitted, insert them into the locations to which they have been ground.
6.27 Lubricate the valve stems prior to refitting
28 Refit the spring seat then, working on the first valve, dip the new valve stem seal in fresh engine oil. Carefully locate it over the valve and onto the guide. Take care not to damage the seal as it is passed over the valve stem.
Use a suitable socket or metal tube to press the seal firmly onto the guide (see illustration).
6.28 Fitting a valve stem oil seal using a socket
29 Locate the valve spring on top of its seat, then refit the spring retainer.
30 Compress the valve spring, and locate the split collets in the recess in the valve stem.
Release the compressor, then repeat the procedure on the remaining valves.
31 With all the valves installed, place the cylinder head face down on blocks on the bench and, using a hammer and interposed block of wood, tap the end of each valve stem to settle the components.
32 Refit the camshaft, followers and shims (as applicable) as described in Part A, B or C of this Chapter.
33 The cylinder head can then be refitted as described in Part A, B or C of this Chapter.