Oil leak

Hi guys.
Just throwing an issue out there for some thoughts.
Recently I've noticed the bottom of my RV is getting a streak of clean looking oil along the exit ramp and the general bottom of the belly is getting a little discoloured, brown oily look. I pulled the cowls (hate that job) and found the lower left internal cowl oily, the oil stain starting from the front cylinder (left side from pilots view). I noted some oil hanging off the induction tube bolts and the tube surface was oily as well. Pulled the induction tube off the engine after a run a& found some oil residue inside the tube, looked a bit oily up in the intake port as well. After shut down I hear what sounds like a pressure relief valve activating, gurgling sound around the front of the cowl opening. Cleaned it all up ran it and a after 2 hrs it's come back. I suspect a crack perhaps in the intake port somewhere or oil ring issues? No oil showing externally on the cylinder itself. Oil consumption seems to be slightly more than usual, about 8 hrs per Quart where is was usually 8.5-9 hrs per Quart.

Comps are good and the engine (IO360, 600 hrs) runs sweet.

Thoughts guys?

If there is oil inside the cowl and drips observed on the bottom of points on the underside of the engine, there is a leak. I have chased and found a number of small leaks on my engine since first flight - and 100 hrs. I found the factory new M1B had no gasket under the vacuum pump plate just recently.

An experienced mechanic said start at the top of the engine fix the leaks and keep working your way down. Oil drips downward. A single hanging drop of oil is an indication of a leak above it. Look above the intake pipes, like rocker cover gaskets.

Keep looking carefully, it might take a while. It is measurable in oil consumption, but I can see more variable than you mention just in ground operation differences (oil temps) before take off.

I may change my mind and give up, but no proper engine should leak.

I have found the little rubber connections in the oil return tubes to be a common source of leaks similar to what you describe. And depending on how the clamps were installed, either very easy or nearly impossible to tighten!
Andy

N729LS said:

I have found the little rubber connections in the oil return tubes to be a common source of leaks similar to what you describe. And depending on how the clamps were installed, either very easy or nearly impossible to tighten!
Andy

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We're the only humans on the planet dumb enough to accept slotted hose clamps on $30,000 engines.

The rubber extrudes through the slots, the clamp loses pressure, and the hose leaks.

So what clamps should we be using in these circumstances, taking into account the access limitations. I too suffered leaks here in the first few hours.
Tom
RV-7
IO360-m1B

tgmillso said:

So what clamps should we be using in these circumstances, taking into account the access limitations. I too suffered leaks here in the first few hours.
Tom
RV-7
IO360-m1B

Click to expand...

I used these spring clamps.

Hose Clamp, Dia 17mm x0.85mm from Grainger.com item #2UTG4

It was an experiment with 6000 hose from Spruce. It is dry as a bone for last 100 hrs, at least from the return hoses.

Excellent. Thanks.
Tom.

I did the same. Used new spring clamps and oil rated hose from the auto parts store.

"Power Steering Return" hose is good for this application: hot oil under low pressure. I installed mine 16 years ago and it still looks like new.

correct clamp

is oetiker stepless, in stainless. available in US through Grainger, amazon - but check source from the latter, and do not select the '2-ear' variety. You will need the oetiker pliers for install/ removal. This avoids relying on 'spring' in spring clamps, over years of use.

https://www.grainger.com/category/brand/oetiker

ymmv but the only screw clamps left in my a/c are on the defroster tube ['cuz I ain't got to them yet]