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While inspecting the front 3 spark plugs (bank 2) on a 2GR-FE (2009 Toyota Venza), I noticed the spark plugs have oil along the entirety of their threads.

There was no oil pooling the the spark plug tube or on the ignition coil packs (just a few drops/smears here or there).

There was wetness at the spark plug tube seals and when I blew it out with an air compressor, some oil droplets splattered everywhere.

There is no perceived drop in oil level between oil changes.

Seems not ideal, but does it look like it's ok to forgo opening up the valve cover(s) and replacing spark plug tube seals for now? Since there was no pooling I'm thinking it could be a slow leak due to age.

Pics:

Some oil glistening on spark plug tube seal at valve cover, and a drop of oil at the spark plug, but no pooling: enter image description here

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Oil residue on seat and threads, with spark plug removed: enter image description here

Spark plug for cylinder #6: enter image description here

Spark plug for cylinder #4: enter image description here

Spark plug for cylinder #2: enter image description here

Just for fun, endoscope images from inside the cylinders:

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EDIT: Pics of cylinder walls and cylinder head taken with a 45 degree mirror in front of the endoscope. Only the middle 1/3 crescent in the images is relevant.

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adatum
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1 Answers1

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If the valve cover gaskets are leaking, then there will be oil pooling in the bottom of the spark plug well. That's not happening and so that's not where the oil on the threads of your plug is coming from.

In this case it certainly appears to be coming up from the combustion chamber. The two most common ways of oil getting in are:

  1. Leaking intake valve guides which allows oil to leak from the cylinder head, down the stem of the valve, and into the chamber.

  2. Leaking piston rings that don't properly scrape oil from the cylinder wall and allows oil to remain on the cylinder wall as the piston does its down stroke.

In either case that oil is compressed and forced up around the threads of the spark plug. You also get the carbon buildup you are showing on the top of the piston.

It's possible there is some oil leaking into the well around the valve cover gasket but to my eye that doesn't appear to be the main source of oil here.

jwh20
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