Gaskets oil seals should be replaced

Gaskets and oil seals should be replaced if worn or leaking, or whenever removed during servicing. Replacement is simple, but some engine dismantling may be necessary to reach them. Buy gasket sets from a dealer for the make of car, and state clearly for what parts they are needed.
Replacing a rocker or cam-cover gasket
Before removing the cover, note the positions of any pipes and wires round it or fixed to it, which have to be removed before it can be freed.
Replacing gaskets and oil seals
You may need to take off the air cleaner (See Air filter change), which may also have pipe connections.ring seal.
The cover is fixed by nuts or bolts on top, or by screws round the edge. Loosen them all and remove them with their washers. If there are several oil-sealing washers under each fixing, note their order.
Carefully lift off the cover. If it sticks, gently tap it sideways with a soft-faced rawhide or nylon hammer, or with the heel of your hand.
Replacing gaskets and oil seals
If necessary, lever it gently with a broad screwdriver blade, but take care not to bend the flange or damage the head.
Take off the gasket from the cover flange or cylinder head, noting how it is attached. Some gaskets have tongues that fit cutouts in the flange; others are stuck to the flange with sealant; some just fit into the flange groove.
Cover the valve gear with a clean cloth to prevent dirt getting into the working parts of the engine.nok seal.
Replacing gaskets and oil seals
Use a piece of wood to scrape off all traces of the old gasket from the head and cover. If total removal proves difficult, use a broad screwdriver blade, but take care not to scratch the seating.
Lift off the cloth, making sure no debris falls into the valve gear.
Fit the new gasket to the cover or head — whichever the old gasket was fixed to.
Replacing gaskets and oil seals
If it was stuck to the cover, smear gasket sealant along the cover flange and upper gasket and leave it to dry for a few minutes.
Fit the gasket to the cover, making sure any screw holes line up. If the gasket has tongues, fit them into their cutouts.
Some gaskets are in two or three pieces dove-tailed together. Make sure the pieces join up properly.cap seal.
Replacing gaskets and oil seals
Refit the rocker or cam cover, aligning its fixing holes with those on the head. Check that the gasket edge aligns with the cover flange all round, and is not distorted. If necessary, adjust it gently with tweezers or long-nosed pliers. Tighten bolts evenly to just compress the gasket.
Refit all pipes and wires, and the air cleaner. Start the engine and check for oil leaks.