Valve (Rocker) Cover Oil Leak

[Nicolas Aristodemou]

Since the major overhaul of my engine 6 months ago I am struggling to address the annoying problem of oil leaks (in 3 locations) from the valve cover gasket. I have replaced the gasket with new MB part twice this year but still I see the perimeter of three  of my spark plugs  wet with fresh engine oil which subsequently drips down the cylinder block and messes the garage floor. Not too much but annoying enough.

It is such a trivial issue and yet so hard to fix. The 3 fixing bolts on the valve cover are tight enough and fix securely the cover on the block with the gasket tightly sandwiched in place.

I didn’t try any sealant since rocker cover is taken out frequently for valve adjustment, cylinder head retorquing etc.

But if this is what other people do to have an oil tight seal then I would try and use a sealing paste.

[Charles 230SL]

hello Nicolas, are you sure its the valve cover that's leaking and not a couple of ball stud adjusters?

..I have replaced the gasket with new MB part twice this year but still I see the perimeter of three  of my spark plugs  wet with fresh engine oil which subsequently drips down the cylinder block and messes the garage floor..

Leaking ball stud adjuster threads will leak oil onto/around the spark plugs.

[Nicolas Aristodemou]

Hi Charles and thanks for your input.

 The oil leak is external, around the spark plugs cavity where the plugs are threaded and tightened on the cylinder head. When I remove the spark plugs their whole  thread is bone dry and the electrode appearance grey as it should be.

Even if the threads of the ball adjusters leaked how could this oil find its way externally onto the cylinder head? Surely any external oil leak should go passed the cover gasket.

Unless there is something else that I don’t see...

[ja17]

The threaded holes of the ball studs emerge  above the spark plug outside the head! If you remove one of the plugs and feel above the spark plug opening you can actually feel the bottom of the ball stud. If the threads are not sealed, then you can have a leak around the spark plug. Removing the leakers and re-sealing them will solve the issue. It is a bit of work with some remote risk of damage to the threads in the head. Unfortunately there is no easy way to know if the threaded ball studs are leaking on the other side of the head. In this case the treaded holes emerge in the exhaust ports of the head. If these leak the oil simply burns off with the exhaust, resulting in some mysterious oil usage.

[Nicolas Aristodemou]

Thank you Joe, I had no idea about that! It seems very inconvenient to get it fixed so maybe I should learn to live with it. I have no measurable oil consumption between oil changes (every 3000km) but even a slight drop on my non porous ceramic garage floor looks very big since it spreads out and stays there till I wipe it clean.

Thanks to you and Charles for pointing me to this direction.