Volkswagen Golf/Jetta 2 manual

Cylinder head - dismantling and overhaul
Engine repair procedures - 1.05 and 1.3 litre pre August 1985 / Cylinder head - dismantling and overhaul


Dismantling
1 Remove the cylinder head and camshaft, as described in the previous Sections.

2 Using a valve spring compressor, compress each valve spring in turn until the split collets can be removed. Release the compressor and remove the retainers and springs (see illustrations). If the retainers are difficult to remove, do not continue to tighten the compressor but gently tap the top of the tool with a hammer. Always make sure that the compressor is held firmly over the retainer.

11.2a Compressing a valve spring to remove split collets
11.2a Compressing a valve spring to remove split collets

11.2b Removing valve springs and retainers . . .
11.2b Removing valve springs and retainers . . .

3 Remove each valve from the cylinder head, keeping them identified for location.

4 Prise the valve seals from the valve guides and remove the lower spring seats (see illustration).

11.4 . . . and valve spring lower seats
11.4 . . . and valve spring lower seats

5 Do not remove the cam follower ball-studs unless they are unserviceable. They are likely to be seized in the head.

Overhaul
6 Use a scraper to carefully remove any carbon from the cylinder head. Remove all traces of gasket then wash the cylinder head thoroughly in paraffin and wipe dry.

7 Use a straight-edge and feeler blade to check that the cylinder head mating surface is not distorted. If it is, then it must be resurfaced by a suitably equipped engineering works. If the cylinder head face is to be resurfaced, this will necessitate the valve seats being re-cut so that they are recessed deeper by an equivalent amount to that machined from the cylinder head. This is necessary to avoid the possibility of the valves coming into contact with the pistons and causing serious damage and is a task to be entrusted to a suitably equipped engine recondition specialist. (see illustration).

11.7 Measure cylinder head depthbetween points indicated
11.7 Measure cylinder head depthbetween points indicated

Minimum allowable depth a = 119.3 mm

8 Examine the valve heads for pitting and burning. Renew any valve which is badly burnt. Examine the valve seats at the same time. If the pitting is very slight, it can be removed by grinding the valve heads and seats together with coarse, then fine, grinding paste. Note that the exhaust valves should not be re-cut, they should be renewed if the sealing face is excessively grooved as a result of regrinding.

9 Where excessive pitting has occurred, the valve seats must be re-cut or renewed by a specialist.

10 Valve grinding is carried out as follows.

Place the cylinder head upside down on a bench with a block of wood at each end.

Smear a trace of coarse carborundum paste on the seat face and press a suction grinding tool onto the valve head. With a semi-rotary action, grind the valve head to its seat, lifting the valve occasionally to redistribute the grinding paste. When a dull matt even surface is produced on both the valve seat and the valve, wipe off the paste and repeat the process with fine carborundum paste as before. A light spring placed under the valve head will greatly ease this operation. When a smooth unbroken ring of light grey matt finish is produced on both the valve and seat, the grinding operation is complete.

11 Scrape away all carbon from the valve head stem and clean away all traces of grinding compound. Clean the valves and seats with a paraffin-soaked rag, then wipe with a clean rag.

12 Check for wear in the valve guides. This may be detected by fitting a new valve in the guide and checking the amount that the rim of the valve will move sideways when the top of the valve stem is flush with the top of the valve guide. The rock limit for the inlet valve is 1.0 mm and 1.3 mm for the exhaust valve.

This can be measured with feeler blades if you use a clamp as a datum but it must be with a new valve. If the rock is at or below this limit with your old valve then this indicates that the existing guide(s) do not need renewal. Check each valve guide in turn but note that the inlet and exhaust valve stem dimensions differ, so do not get them confused. If the rock exceeds the limit with a new valve, this will indicate the need for new valve guides as well. The removal and refitting of new guides is a task which must be entrusted to a specialist.

13 If possible, compare the length of the valve springs with new ones and renew them as a set if any are shorter.

14 If the engine is still in the vehicle, clean the piston crowns and cylinder bore upper edges but make sure that no carbon drops between the pistons and bores. To do this, locate two of the pistons at the top of their bores and seal off the remaining bores with paper and masking tape. Press a little grease between the two pistons and their bores to collect any carbon dust which can be wiped away when the piston is lowered. To prevent carbon build-up, polish the piston crown with metal polish but remove all traces of the polish afterwards.


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