Friday, March 26, 2010


The engine oil and strainer should be attended to (never change the oil without also cleaning the strainer). The textbook method of changing the engine oil starts with the advice to warm the engine thoroughly in order to thin the oil and so help more of it drain. The author sees two drawbacks to this working method. Firstly, the oil (which plays a part in cooling the engine) will be very hot indeed and quite capable of burning you. Old engine oil can cause problems if it is allowed to come into contact with your skin; these will probably be exacerbated if you pre-heat the oil! Secondly, if the oil change is carried out after the car has been standing idle overnight, then the oil will have had plenty of time to drain down to the sump. Whichever method you choose is up to you.
You will need a receptacle for the old engine oil. You can buy special containers with deeply dished sides for this purpose, and they do offer you the advantage of being able to seal them once the oil has drained. However, an old five litre oil can, with one side cut away, serves just as well. Old engine oil is a very good rust preventative when painted onto steel surfaces. If you can find no use for the old oil, however, then dispose of it properly; most garages will accept it on your behalf for recycling.
To drain the oil, place the receptacle underneath the sump drain plug and then undo the plug. The oil will start to drain. To increase the flow rate, unscrew the oil filler cap. Leave the oil draining for fifteen minutes or longer if possible.
When the bulk of the oil has drained, you can attend to the strainer. The strainer assembly is to be found underneath the centre of the crankcase, where it is secured by six nuts. Place an oil receptacle under the strainer base plate (it will already be in the correct position on some cars, because the drain plug is situated in the centre of the base plate) and undo the nuts, taking care to keep oil off your hands.
Remove the strainer assembly. Clean off any of the old gasket material and wash the strainer in neat petrol. When refitting, use new gaskets.
Check the tension of the generator drive belt and, if it deflects more than % in. under firm thumb pressure, tighten it. To do this, lock the generator by inserting a thin screwdriver through the hole in the front pulley half against one of the screws in the generator, then remove the pulley nut. There should be a number of shims between the two halves of the pulley, and removing some of these will increase the belt tension (and vice versa). Keep the spare shims under the pulley nut on the outside of the pulley. If you do not save the shims and decide to fit a new belt (if the existing one becomes frayed or cut) then you will have to obtain and fit shims; otherwise the belt would be too highly tensioned and it would place unacceptably high strain on the generator bearings.
Disconnect the high tension (HT) leads from their respective spark plugs; if you are unsure about which plug connects with which lead then either place a folded masking tape tag on each lead and write onto this the relevant cylinder number, or mark 1,2,3 or 4 bands on each lead (according to which cylinder it runs to) itself using typist's correction fluid. The illustration shows the cylinder numbers (the pulley end is at the rear of the car, the flywheel is inboard) and the firing order.
The valve clearances have to be adjusted – happily, this is one of the few tasks which can be accomplished easily with the engine still in the car. Chock the front wheels, raise the rear of the car and support it on axle stands.
The engine should be cold. Begin by cleaning all dirt from the two rocker covers, and ensure that no dirt from nearby components can fall onto the valve mechanism. Disconnect the HT leads (mark them if appropriate with the relevant cylinder number to aid correct replacement) and remove the spark plugs. The rocker covers are held by spring clips, prise these away and lift out the covers. Take the car out of gear.Remove the distributor cap, then turn the engine until the rotor arm is pointing where the number one cylinder HT lead terminates in the distributor cap – do this either by pulling the generator drive belt or with a spanner on the generator pulley bolt (if the engine will not turn over then the drive belt is slipping and should be tightened before carrying on). The rotor arm should be pointing at a notch in the distributor body rim. Thenotch in the crankshaft pulley should be pointing upwards, in line with the crankcase centre join or, if there are two notches, they should be slightly to the right of this line.
Check the valve clearances for number one cylinder. Try to gently place a feeler gauge of 0.006 in. (0.15 mm) in between the rocker arm and the top of the valve stem; if it will not go in or if it is very slack then the clearance
has to be adjusted. Undo the locknut on the adjuster screw, then place the feeler gauge in position and tighten the adjuster screw until very slight drag can be felt on the gauge when it is moved. Remove the gauge, hold the adjuster in position with a screwdriver and tighten the locknut using a ring spanner. Re-check and re-adjust if necessary.
Turn the engine anti-clockwise until the crankshaft has gone through 180 degrees (the rotor arm will have travelled through 90 degrees and be pointing at the position of number two HT lead within the distributor cap). Check and, if necessary, adjust the clearances for number two cylinder. Repeat the anti-clockwise movement as before (rotor arm 90 degrees, crankshaft 180 degrees) and check and adjust the clearances for cylinder number three, then repeat the process for cylinder four.
There is also a quicker method, which must only ever be used when the engine is stone cold. Turn the engine over until the crankshaft pulley notch is at top dead centre. On one cylinder head, three rockers will have movement, on the other, just one. Adjust those valve clearances, then turn the crank pulley through a complete rotation, when the previously engaged rockers will now have movement; adjust the valve clearances of these.
Re-fit the rocker box covers, using new gaskets.

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