Oil splatter from intake tube?

[EricJ]

Maybe my inexperience is showing, but I have multiple cylinders making little oil splatters that appear to be coming from the region of the intake tube connection with the cylinder.   It's not a lot of oil, but it's been consistent that there are these little splatters in the vicinity of the tube, sometimes on the inside of the cowl when removed.    This time I noticed that there's actually a little bead of oil on one of the intake tube fasteners.

Is this common or something that needs attention?

[201Steve]

Curious what your bottom plugs look like. I looked into why I would be getting oil into my intake sump not long ago... best I could come up with was oil seepage from rocker box through the intake valve guide, and into the intake. Combination of failed oil return ring AND a stuck intake valve? Highly unlikely.  In your case, even a more radical idea to suggest it's happening on more than one cylinder. To that end, I would be very suspect about it coming from another source and squirting or blowing onto the location you find it. A simple way to check would be to inspect your intake sump drain hose coming off the sniffle valve on the bottom of the intake manifold to see if oil is accumulating inside the manifold. Ideally you would pull the sniffle valve for a sure fire sign, but most of them require you drop the exhaust to access (depending on clearance). Just some misc thoughts.

[carusoam]

I think splatter is the right term for this...

Looks like an external leak is getting the oil blasted towards the intake tube...

Some is landing on the cooling fin above, lots o drops are hitting the tube...

All of it is heading down with gravity...

Start with all the obvious spots to begin with...

Like the oil fill tube seal...

That’s too big to be a challenging leak...  

Wash clean, apply the foot powder/spray deodorant...

PP thoughts only, good luck with the hunt.

Best regards,

-a-

[PT20J]

Doesn't look right. Oil at the top end usually comes from pushrod seals, rocker cover gaskets or drain back tubes. At the museum where we have a lot of leaky radials, when one leaks more than usual, the mechanic has us wash it down thoroughly with solvent and let it dry and then ground run it up to temp and shut down and see what's oozing. Might be worth a try.

Skip

[EricJ]

It's still uncowled and I plan to fly tomorrow, so will clean it up before the cowl goes back on.   I checked the drain-back tubes, pushrod tubes, valve cover gaskets, and the rocker shaft cover gaskets.   Nothing looks like an obvious source, although there's a slight possibility it could be oozing down from the rocker shaft covers, but I don't know what's making it splatter like that other than maybe vibration.   Whatever it is, it doesn't do it very much because that's about as much as shows up between oil changes.   

Thanks for the input so far.

Edited February 6, 2021 by EricJ

[Bartman]

In the past I have added some UV Dye and after though cleaning did one trip around the pattern and looked for leaks with the UV light. It’s pretty obvious where it is coming from. 

[Ragsf15e]

I recently had a leak from the pushrod gaskets.  The oil was seeping into the upper cooling fins and then the cooling airflow from top to bottom was splattering it onto the intake tubes below.  Wasn’t as much as yours.  My mechanic pointed out the seep from the gasket into the fins.  Before that it wasn’t visible to me.  Reasonably easy fix.

[larrynimmo]

On mine...Lycomming installed stainless steel screw clamps (lime the old fuel line or radiator hose). I tightened those clamps and greatly reduced amount of oil leaking

[Yetti]

orange valve gasket covers?   usually the drain back tubes leak at the top and or the bottom.   Last one I fixed I tried using permatex on the threads.   You bottom plug looks clean.