R107 Valve Cover Gasket Replacement

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Valve cover gaskets are the most common oil leak on R107 V8s. Oil running down the heads onto the exhaust manifolds causes smoke and smell, and it makes every other leak harder to find. The job is straightforward.

Leak signs

• Oil wetting the side of the head under the cover edge
• Burning oil smell or wisps of smoke after a drive
• Oil in the spark plug wells or on plug wires
• Oily residue on the exhaust manifold

Parts needed

• Valve cover gasket set for your engine (includes the cover gasket and the seals for the mounting bolts)
• Half-moon or cam plug seals if your engine uses them
• Spark plug tube seals where fitted
• Gasket sealant only where the manual calls for it, usually at the corners where the timing cover meets the head

Step-by-step removal

1. Let the engine cool. Disconnect the battery.
2. Remove the air cleaner and anything mounted over the cover: throttle linkage, vacuum lines, wiring and hoses. Photograph them first.
3. Remove the cover nuts and their sealing washers.
4. Lift the cover; tap gently with a rubber mallet if it sticks. Do not pry against the sealing surface.
5. Clean the cover and head surfaces with a plastic scraper and solvent. No gasket material should fall into the engine.

Sealing tips

• Use a thin dab of sealant at the joint between the head and the timing cover area if specified; too much squeezes into the engine.
• Make sure the new gasket is seated in its groove all round.
• Replace the rubber washers under the nuts; old ones are the cause of many leaks after a new gasket.

Torque

Tighten the cover nuts gradually and evenly to the factory torque, which is low. Over-tightening crushes the gasket and distorts the cover. Recheck after the first heat cycle.

How long it takes

Allow about two to three hours for both sides on a V8 if you are careful with the linkage and wiring. The right side is often more crowded.

While the cover is off, look at the cam lobes, the timing chain and upper guide rail. It is the best chance to spot wear early; see timing chain interval.

Related reading

• R107 oil leaks
• R107 Heater Valve (Monovalve/Duovalve): No Heat or Heat Stuck On
• Best Car Cover for an R107 (Indoor and Outdoor)

Quick answers

• Should I use RTV on the whole gasket? No. Use sealant only where the manual specifies, usually at the joints. A full bead of RTV can squeeze into the engine.
• Why is it still leaking after a new gasket? Common reasons: old rubber washers under the nuts, a bent cover flange, over-tightening, or the leak was actually coming from somewhere else, like the timing cover or cam plugs.
• Can I reuse the old gasket? Not worth it. A new set costs little compared with the time to do the job twice.
• Do I need to remove the fuel lines? On most R107 V8s, some injection lines or linkage must move. Plan to replace any sealing washers you disturb.