Oil leak first runs

Well it was actually the second run. The first engine run happened yesterday for my plane. The first was short maybe 3 min, CHT only 160 or so. Climbed out and inspected everything and there were no leaks.

I went off to fly my first flight profile with my Flight Adviser and when I returned I did another engine run and this one was maybe 5 min max CHT 270. (Engine was totally cool before this second run)

What I found on post run inspection is a tiny bit of oil on top of the nut on two different cylinder #2 and #3. Both are the lower left nuts (the large one). The oil appears to becoming up through the threads, oil on top of the nut but not the sides. I have not yet done another run. When I cleaned off the oil no more appears to seep out.

Anyone out there seen this and have any ideas? I am grounded, which is a disappointment, I was really excited to do the first flight today weather permitting, but now I want to run this leak down.

Cheers
Mike

Mike,
I hope some experts will chime in with advice more credible than mine.
Having done twice what you are about to do for the first time, I don't think you have an oil leak.
Real oil leaks are more common on fittings that weren't tight. Having a drop of oil show up somewhere on a nut or thread is more likely a remnant of spilled oil
working its way out of whatever crevice it was in while sitting on the ground.
I would worry about a drip, but not a drop appearing somewhere especially not on a cylinder nut.
I am meticulous with oil and installation and even a little oil somewhere bugs me. As careful as I am, I spill a drop or two once in a while and although I wipe it clean, some of it will eventually show up later in the form of a drop or a slight smear along the bottom of the engine.
Run it up again and if it does not leak you are good to go. Remember to keep these ground runs short to prevent overheating and cylinder glazing.
Good luck on your first flight

A couple of drops of oil on a cylinder base nut wouldn't bother me, and certainly wouldn't keep me from making a first, second, third, or thousandth flight.

Unfortuately, Lycomings can and do leak oil. If the leaks persist and are enough to bother you, speak to your engine builder.

Relief

Thanks for the input guys, I had built this up in my mind last night into something really bad. I would still appreciate other opinions, but for now it seems that another engine run and if no worse then perhaps a first flight. Monday has promise weather wise, yesterday was awesome, cool, calm and high overcast, but I needed dual time to fulfill an insurance requirement and still had to install some fairings.

Again please post your opinion, I like to gather as much information then make a measured decision based on all inputs.

Cheers
Mike

Tighten oil drain back tube clamps.

Mike - I have had similar evidence of little "leaks" in the same spot from day one and still do today. (550 hours). It has never been enough to even spot the floor. I am no expert for sure but I seriously doubt you have a problem.

The lower left 1/2x20 nut is on a case stud not a through bolt. (In other words, it's holding the jug on the case, but it's not part of the system that holds the case together.) As someone suggested, very possibly collecting there but not leaking there. Checking the runback tube is good advice. If that doesn't clear it up, clean well, and spray some talc, foot powder, or dye penetrant developer in the area. Where the leak is coming from will show up better.

Dan

After my early flights, I had drops of oil appearing everywhere. I only had one leak, though, the steel fitting coming out of the oil cooler (or going into the oil cooler, I forget which) and it wasn't even that big of a leak. But whatever magic happens in that cowling put a drop of oil in all sorts of interesting places that were nowhere near the place from which it was actually coming.

I'm not saying that's what's happening here -- there's no way for me to know that -- just that to doublecheck the actual oil lines first.

Leaks

I have rarely seen an aircraft engine that didn't leak oil. Then it was a matter of "yet"

When you torque Lycoming jug nuts the manual calls for them to be lubetorqued. This means the builder applies a couple drops of oil to each stud just before torquing. That sits in there and when it warms up and you shake it, out it comes. Keep wiping it away and it should chill out soon.

its your past coming back to haunt you

Nemo, it must be all that Tomcat time, all the runs, drips and entertainment there has followed you to here. what was that old adage, if it ain't leaking something it must be empty?

seriouly tho, i agree with the thought to clean it off, likely residual, run it , fly it, monitor. on mine, i had a bit of seepage where the oil filler tube screwed into the engine, solved with a realgasket.

enjoy that first flight, it will be awesome!

Funny

Stump said:

Nemo, it must be all that Tomcat time, all the runs, drips and entertainment there has followed you to here. what was that old adage, if it ain't leaking something it must be empty?

seriouly tho, i agree with the thought to clean it off, likely residual, run it , fly it, monitor. on mine, i had a bit of seepage where the oil filler tube screwed into the engine, solved with a realgasket.

enjoy that first flight, it will be awesome!

Click to expand...

Stump, you make a good point, The Rhino, Tomcat and even the Eagle all had drips. I remember the JP-8 that would drip out of the Eagle. I had a Russian Test pilot tell me the Eagle was a bad design when I was sitting with the Jet at the Paris Air Show. All while I am looking at the Foxhound that looked like the rivets where set by a third grader with a hammer.

It rained all day today so no engine run, I will try one tomorrow and a short Taxi, looks like I might get a break in the weather in the next few days, I plan to spend the day at the airport just in case there is an hour or two of good weather. Sure wish I had gotten this done two months ago, oh well.

Cheers

Fairly Sure of location

DanBaier said:

The lower left 1/2x20 nut is on a case stud not a through bolt. (In other words, it's holding the jug on the case, but it's not part of the system that holds the case together.) As someone suggested, very possibly collecting there but not leaking there. Checking the runback tube is good advice. If that doesn't clear it up, clean well, and spray some talc, foot powder, or dye penetrant developer in the area. Where the leak is coming from will show up better.

Dan

Click to expand...

Dan,

I meticulously looked over the engine after this first engine run, there was not oil even on the side of these nuts and none anywhere else, it definitely seeped out of the threads.

Thanks you for the ideas though, I will keep this in my bag of tricks for future use.

Praying to the weather gods for some dry days ahead.

Cheers