Valve Cover Gasket – What Can Go Wrong And Why

Valve Cover Gaskets
Valve Cover Gaskets

The valve cover sits on top of the cylinder head and does just what its name suggests, covers the valves.

The valve cover gasket is what seals this cover to the cylinder head.

Most valve cover gaskets are from molded rubber.

The valve cover gasket has several jobs:

  • Protects cylinder head parts from the elements
  • Stops important lubricating oil from leaking externally
  • Controls air leaks to help promote proper PCV operation

The valve cover gasket is very delicate and prone to oil leaks. Over time the gasket becomes brittle and will crack due to exposure to dirt, debris, heat and other elements. When this occurs, the gasket can lose its integrity and leak. If not replaced in time, a bad valve cover gasket can lead to complete engine failure.

First let’s make sure you actually have a leak coming from your valve cover gasket.

Luckily valve cover gaskets can usually be pretty easy to diagnose.

The valve cover gasket is almost always the highest seal in the engine.

If a vehicle’s oil is not changed often enough sludge develops, clogging the drainage holes and placing a lot of pressure on the valve cover gasket.

When the gasket is unable to function properly, oil leaks often occur.

Valve Cover Gasket Leak
Valve Cover Gasket Leak

Always Start With A Visual Inspection:

  • Loose or missing bolts or screws
  • Cracks in the valve cover
  • Part of the gasket sticking out from under the valve cover
  • Evidence of a leak in the form of oil or black residue around the edge of the valve cover

Once you’ve proved you have a valve cover gasket oil leak you need to decide how to move forward.

If you have a missing bolt or screw, it should be replaced immediately. Make sure to torque the bolts to the factory recommended torque. So, If you tighten them too much, you can risk breaking the valve cover, and too loose, they can leak.

Common Warning Signs Of A Faulty Valve Cover Gasket:

The Smell Of Burning Oil

  • While the engine is running, the excess oil will drip on other components. These are all hot components that will burn the oil and produce a burning oil smell that is easily recognizable.

Valve Cover Is “Caked” With Dirt And Is Leaking Oil

  • The quickest indication of this problem is when the valve cover/cylinder head is very dirty. Oil attracts dirt and will appear to be “caked” on where its leaking. If you look under your hood and discover that the valve cover is dirty, it’s most likely a leaking gasket.

Oil Level Is Low

  • As oil leaks from the valve cover gasket, it leaves the oil pan. When this happens frequently, it can cause the Engine Oil Light to appear on your dashboard. Consequently, If the engine oil is low, it will reduce its ability to properly lubricate internal engine components. This can build up excessive heat inside the motor and cause serious engine damage.

Engine Is Misfiring

  • Oil On Spark Plug
    Oil On Spark Plug

    Sometimes oil can leak all the way down to the spark plug and eventually seep inside the spark plug tubes. This will cause a misfire or reduce engine performance. It can also cause a fire under your hood if it goes unrepaired.


Proper, regular maintenance and routine oil changes can help reduce the problems outlined above. Consequently, helping you avoid further damage to primary engine components, essentially preventing damage and leaks before they happen.

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