Oil on a Spark Plug? How to Diagnose and Fix Spark Plug Tube Gaskets

If you find oil on a spark plug, on the spark plug threads, or in the spark plug well, oil is leaking from the spark plug well gaskets. Oil collected in the spark plug well, also known as the spark plug tube, is a problem since it can pile up on the ignition coil and spark plug until it causes runability issues and possibly a check engine light. This post covers the signs of a spark plug tube gasket leak, why oil would cover a spark plug or ignition coil, and how you can fix it.

How to Fix Oil in the Spark Plug Well

Symptoms of a Spark Plug Well Gasket Leak

Oil in a spark plug well
Oil in a spark plug well
  • Engine performance issues like high oil consumption or misfires
  • Check engine light
  • Oil collected in the spark plug tube, on the spark plugs, or on the ignition coils
Oil on an ignition coil
Oil on an ignition coil

If the spark plug tube’s o-ring is leaking oil, it can cause problems with engine performance like misfires or consistently low oil levels from excessive oil consumption. A check engine light could also appear on the dash. You may also notice oil on the spark plugs and ignition coils, or find it inside the spark plug tube.

Causes of Oil on the Spark Plugs

Cams, lifters, and valve cover with spark plug well gaskets
Camshafts, lifters, and a valve cover with spark plug well gaskets

Oil lubricates the camshafts and lifters, and these moving parts sputter the oil up against the valve cover so it can fall back to the oil pan. The valve cover has gaskets to prevent oil from collecting inside the spark plug well. If the spark plug tube gaskets are worn, stiff, or damaged, there will be a weak seal, and oil will collect inside of the spark plug tube.

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How to Fix a Spark Plug Well Gasket Leak

Steps for How to Fix a Spark Plug Well Gasket Leak

  1. Remove the Valve Cover

    The easiest way to replace the spark plug well’s o-rings is on a bench with the valve cover removed. Remove the valve cover to access the spark plug well gaskets

  2. Remove the Spark Plug Well Gasket

    Place a flat blade screwdriver between the valve cover and the gasket and tap the screwdriver to wedge it. Then pry up the gasket with a flat blade screwdriver without damaging the metal.

  3. Install a New Spark Plug Well Gasket

    Apply a thin amount of engine oil or grease to the outside of the gasket before installing. Line the gasket into place on the valve cover. Place a socket that covers the size of the gasket on top and press the gasket in by tapping the socket with a hammer. Once the gasket is fully pressed all the way in to the valve cover, repeat this process for the remaining o-rings.

  4. Replace the Valve Cover Gasket

    Once all the o-rings are replaced, replace the valve cover gasket before reinstalling the valve cover

  5. Clean the Spark Plug Tube with Sandpaper

    Before installing the valve cover, clean the spark plug tube of any dark build-up with sandpaper

  6. Replace the Valve Cover

    Tighten the valve cover once the gaskets are replaced and the spark plug tube is clean

  7. Remove Oil from the Spark Plug Well

    Depending on the amount you can vacuum the oil out, clean it out with a cloth rag, or clean it with a cloth rag and a blow gun.

    To clean the spark plug tube with a cloth and blow gun, stuff the cloth and blow gun into the spark plug well so it can catch any oil trying to escape as the air is pumped in. Remove any oil that may have landed on the valve cover.

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Oil on a Spark Plug? How to Fix Spark Plug Tube Gaskets - 1A Auto
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Oil on a Spark Plug? How to Fix Spark Plug Tube Gaskets - 1A Auto
Description
If you noticed oil is on the spark plugs, the ignition coil, or in the oil well, find out what causes it and how to fix it with these steps from expert mechanics.
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1A Auto
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