Oil in weird spot in cabin
 

Noticed a couple drops of oil underneath the throttle cable where it meets the throttle lever in the cabin. In my RV-8, I have the side panel throttle quadrant mod, but for purposes of this discussion should be considered identical to a stock build.

The other end is connected to a Lyc IO360M1B. The end of the cable is in the vicinity of the low pressure oil return lines, so I decowled to investigate. There was a touch of moistness in that area but nothing more than usual, and certainly nothing obvious that caught my eye. I tightened the hose clamps and buttoned everything up.

Any thoughts? Am I missing something? I checked the other two cables - prop and mixture - and they are completely dry (none of them are in the vicinity of any moistness anyway).

Finally, do any of you replace those short runs of hose from the aluminum return lines to the case?

Here are some pix:

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MANY thanks in advance.

Jon Weiswasser
N898JW, RV-8

Any chance it could be brake fluid? I had an occasion once where I climbed to high altitude and a bubble in my brake lines burped out the reservoir, spilling a bit on the firewall. A few drops followed the brake line through the firewall where the reservoir penetrates it, and followed the line down to the right side master cylinder, where I observed it and thought I had a leaking master cylinder.

nope... pretty clearly motor oil.

A Prank?
 

A buddy playing a prank on you? I have "a friend" that used to do this from time to time with various mechanical devices of mine. It was really funny! :(

Lol. No prank.

Jon,

I can't tell by looking. Especially on my cell phone. Do you have an electronic oil pressure gauge with remote sender? Or rather does your oil pressure line come through the firewall to the gauge?

Jim

It's electronic (g3x) with a remote sender. the drops on the floor on the left are directly under the throttle cable termination where it joins the lever. the cable housing itself is a little moist with oil, so I don't think that its coming from somewhere else...

May be capillary action or high pressure bringing it in from the FWF portion of the cable? Oil leak somewhere on the engine and it collects on the cable or sheath in the high pressure area FWF and capillary action or high cooling air pressure pushes it through the cable channel into the low pressure area in the cabin?

Or the cable itself got (over)oiled at some point?

Yeah - thats my working hypothesis. It is routed and terminates in the area just inside of the induction tubes, between the tubes and the case and bounded at the top by the cylinder and the bottom by the oil pan. Ending there, it actuates a bell crank which then moves the throttle body arm (Van's design for an IO360M1B). I believe that oil oozing through those cheap, short, runs of automotive-type tubing from the aluminum part of the low pressure oil return lines to the case has wicked into the cable and through a combination of time and pressure worked itself back to the other end of the cable in the cabin.