Difference between revisions of "NG 900/9-3 Valve Cover Gasket"

Latest revision as of 08:10, 10 August 2010

Overview

Valve cover leaks are common. Sources include the grommet at the valve cover opening for the PCV system, the valve cover plug at the end of one of cam used for the distributor shaft on non-turbo engines, and the valve cover gasket itself. Most valve cover gaskets lose their elasticity eventually and start to leak. Replacement is fairly straight forward, and a good opportunity to inspect the valve cover for oil deposits which form in many engines by 100k miles.. There are relatively few tools required (T25 and T30 bits, a small ratchet with a bit holder, a new set of gaskets (there is an inner and outer gasket, sold as a kit), and optionally some gasket sealer or gasket "dressing".

Removal and Replacement

Tools

• 3/8 drive ratchet
• T-30 bit or driver (ignition cassette)
• T-40 bit (valve cover bolts)
• 10-mm socket
• Torque wrench (optional)
• Solvent (cleaner)
• Wire brush (valve cover groove)
• Grease or gasket dressing
• Permatex gasket sealer

Torque Wrench Settings

• Ignition cassette, 8 lb-ft
• Valve cover bolts, 11 lb-ft

Parts

• Valve Cover Gasket Kit - p/n 8822041

Access

Ignition Module (IDM or DIC)

The plastic cover over the intake manifold and the Ignition Module have to be removed first. The ignition module (IDM, a.k.a. the DIC) is held in place by T30 screws and an electrical connector.

Fig. 1 - Ignition Module (IDM or DIC)

Other Components

• Air filter box, 10-mm nuts
• Air intake hose, hose clamps
• PCV Nipple, unplug from valve cover
• PCV pipe screw, T-30 torx
• Oil filler tube bracket, 10-mm hex bolts

Fig. 2 - Other Components

Removal

Valve Cover Bolts

The valve cover is attached by 16 T-40 torx bolts. Eleven bolts on the outside of the valve cover, and five on the inside. The bolts are fairly tight, and have to be removed using a small ratchet with a short extension and a T-40 bit holder. Clearance for the bit holder is tight near the PCV pipe and the oil filler tube.

Fig. 3 - Valve Cover

Valve Cover

The old gasket usually sticks to both the valve cover and the head. It may take a tap with a rubber mallet to break the seal, and some careful prying with a screwdriver before the valve cover comes loose, and can be lifted off. The top of the engine, timing chain, timing gears etc. can now be inspected.

Fig. 4 - Valves

Assembly

Gasket Replacement

The valve cover groove should be cleaned and dried before inserting a new gasket. It can be coated with a few dabs of tacky grease or gasket sealer/dressing to help hold the gasket in place when the cover is turned over for assembly. The surface at the head where the valve cover will be seated should also be clean and dry before reassembly.

Fig. 6 - Valve Cover Gaskets

Gasket Sealer

Sometimes a new gasket is not engough to stop the leaks. In that case, small amounts of silicone gasket sealer may have to be used in areas where the cover leaks, like the half-moon seals which close off openings in the block. Otherwise some tacky grease or gasket dressing is sufficient.

Fig. 7 - "Half-moon" seals to be filled with Gasket Sealer

Valve Cover Plug

If the plug was also leaking, it can be replaced or sealed with Permatex sealer, as shown on the left. For more details on the plug:

Fig. 8 - Valve Cover Plug

Valve Cover Plug Repair

Valve Cover

The valve cover is turned over carefully with the gasket in place and replaced on the engine. Use two bolts to locate the cover in the correct position. Next check the position of the half-moon seals. Finally, tighten valve cover bolts to about 11 lb-ft, in the sequence shown at left.

Fig. 9 - Valve Cover Bolt Tightening Sequence

Remaining Parts

Reassemble in reverse order,

• Oil tube bracket
• PCV pipe
• PCV nipple, clean and insert into the valve cover bushing
• Air box
• Air Intake hose
• Ignition Cassette