Oily grime in cylinders

[wwdwgs]

I looked inside the cylinders with borescope and found that internals are covered with oily grime/soot, especially in number 1 and 4.
Also - oil deposits inside the intake.
Is it due to bad o-rings of Air-Oil Separator?

cyl 1




cyl 2




cyl 3




cyl 4 (grime is scratched with borescope)



Videos will be available here: https://cloud.degoo.com/share/8OfYGMDbhk6u8EMe5NKnMw

[OK-944]

Have you looked at your spark plugs? Lots of info online about how to check spark plug contacts for signs of oil or gas fouling, pre-ignition, etc. The key here is to make sure you mark the plugs as you remove them, to identify which cylinder each plug belongs to.

Otherwise, while your photos imply that you might need to check the condition of your AOS...the throat of the throttle body looks pretty clean - but you may still want to check around for signs of oil ingress upstream of the intake plenum. Another thing about oil ingress into the throttle body is that oil can breach a compromised (old/dry/cracked) TPS gasket and interfere with the TPS function.

My gut is telling me that you are looking at a refresh (thorough cleanup) and reseal of your cylinder head (valve guide seals in particular). and possibly a gentle lapping of valve faces/seats. All of this is quite straightforward.

If it were me I'd be checking the plugs, and if there were signs of oil fouling I'd be pulling the cam tower and cylinder head to get a better look at things, including taking dial-gauge readings of cylinder inside diameters to see if these are at or close to specs, and turning the crank so that I could get a good assessment of the condition of cylinder walls.

[wwdwgs]

Plug #4 was covered with a black, oily layer. I cleaned it, check the gap and put it back. Did basic tune-up.
Put about 200 miles last year. Last November I decided to replace a water pump, belts, front end seals, cam shaft housing seals.
I really don't want to pull head.
I didn't expect THIS condition inside the cylinders.
Throat of the throttle body is clean, because I wiped it off some time ago.
Now, in order to service Air-Oil separator, I have to remove intake manifold.

[djnolan]

Yes check those spark plugs and post a picture of all 4. #1 & #4 look either fuel or oil fouled. It could be caused by a leaking injector on #1 & #4. Next you could do a compression and leak down test to check for a cracked ring. If that checks out OK, then you could have a bad valve guide seal on #1 and #4. A bad valve guide seal could be caused by a broken inner valve spring. Or a combination of those things. Good Luck

[OK-944]

Removing the intake manifold would give you a chance to check and possibly replace some cracked vacuum hoses underneath - as well as getting you closer to addressing possible AOS and/or injector issues.

[wwdwgs]

Fuel injectors are out, I cleaned them, but didn't check them yet.
I suspected AOS "clogged" when I first discovered oily deposits inside intake manifold (observing thru throttle body).

Djnolan - I didn't take spark plug pictures, and cleaned #4 already. If I could find the old pictures, I'll post them.

OK-944 - yes, I think that removing intake manifold is a necessary "evil".
I just didn't expect to be SO MUCH involved in it.

Note: all cylinders "receive" oil from intake manifold, but #1 and, especially, #4 are "Oily".

Next steps will be:
observing spray patterns of all injectors
getting to AOS and cleaning it, replacing all rubber o-rings.
reinstalling new intake manifold gaskets etc, maybe replacing throttle body to intake manifold gaskets.

Also, thick vacuum hoses could be cleaned or replaced, I don't know their condition yet.

There's no way, I can think of, to clean inside of cylinders without removing head.

What else? Am I missing something?

Also, I assume that the oil pan is grimy, too.