Lycoming IO-360-A1A oil film

[Cody Stallings]

I'm a propeller guy, not a power plant guy. So I need some advice

My company has a 67F, an it has started to leave a little film of oil on top of the starter,oil sump, an the servo. Was doing a dynamic balance on it this week an after shutting it down on the second run, there was smoke venting out of the front cowl opening, so I started investigating. The moist spot where the most oil is accumulated is between #2&#4 cyld.. I have checked the tq on the cylinder flange bolts, all seems well. Went as far as using Eddy Current looking for cracks in the area.

The oil consumption has been about the same 5hr=1qt.

The mechanic says all airplane engines leak oil. He has many yrs of dealing with round engines. So it looks like I'm gonna be dealing with this solo.

Your thoughts would be great....thanks

[Bkingnorth]

1. Through stud?
   

[N201MKTurbo]

If you can figure out how to make it stop let me know.

I have maintained and operated 4 different Lycoming IO-360 engines for over 4000 hours all together. I'm not saying that it is impossible to make this engine leak free, but I've never seen it.

If it is a through stud, you can clean your engine periodically, or spend 5 to 10 K to have the engine R&R ed, disassembled and reassembled.

[fantom]

If a Lycoming isn't spewing a bit of oil, ther's none in it.

[N601RX]

I assume you looked the drain tubes over good. The early through through studs to not use any seals. They rely an an interference fit to stop the oil. If it is the through studs you can get a couple of oversized studs and install them in the field. If I remember correctly the .001 can be installed with out reaming while the .003 requires reaming 1st. If they are loose be careful, the case halves will fret. If this has happened bad enough you can close up the main bearing clearance when retorquing the cylinders. There is a service bulleting that deals with the and stopping leaks around the through studs.

When I overhauled my engine I had oring pockets machined into the case half to prevent oil from leaking out past the through bolts.

[Cody Stallings]

I was thinking through bolt or ,maybe a cylinder base Oring. Do they have a problem leaking too?

The leak is not a huge deal, but I can't handle when something on a plane is not just right.

I am not going to break the engine down to fix this. It was just done 370 hrs ago.

Sense the oil consumption is unchanged, I may be pouting about something that's not that big of a deal.

[scottfromiowa]

There is NOTHING better than two southern gentlemen discussing the particulars of their engines. I fly into my sisters "Sharp County Regional CVK" and always think about how beautiful it is. I bet "Mountain View" is not to shabby either.

[fantom]

, I may be pouting about something that's not that big of a deal.

That happens a lot around here ;-)

[Cody Stallings]

Mt. View is only 25 miles southwest of CVK. An it's a lot more fun to get into on a windy day.....

Stop in sometime for the bluegrass music, shopping an trout fishing.

Stop in the propshop an say hey.

[N201MKTurbo]

Just think about it as automatic external corrosion protection

[Cody Stallings]

Well that's what's strange. There is not much on the belly. I hope I can get it figured out pretty soon.

Speaking of the corrosion protection....

Before we were graced with this awesome flying machine with the backwards tail, I would have to fly a cessna product out to do jobs. That leaked oil so bad cause some one forgot the silk thread at the back of the case.

Now when your going into an Agstrip to work on a Air tractor, no big deal.

But I wanted to run an hide when I would say pull up at million air or Wilson at memphis intl, to work on a KingAir or something along those lines,an it would dump oil all over the ramp.

It was so bad, you could tell what direction the plane was parked.

So glad we have the F now. Hope it don't get that bad.....

[1964-M20E]

It appears that I have a cylinder base O-ring oil leak.  I noticed more oil leaking from the engine lately and after doing some cleaning I was able to see the following.  I plan on removing the cylinder and putting a new O-ring on it.  We torqued the bolts at annual a month ago but no luck.

 

 

 

 

[N201MKTurbo]

The oil looks better then the blue stuff....

[1964-M20E]

The blue is just blue chalk line chalk mixed with lacquer thinner to a paint like consistency and painted on. Clean the area well, paint the blue on, run the engine for a few minutes and the oil leak shows itself. It is leaking enough to warrant doing something relatively quickly.

The blue washes off very easily with any engine cleaning solvent you want to use.

[mike_elliott]

I was thinking through bolt or ,maybe a cylinder base Oring. Do they have a problem leaking too?

The leak is not a huge deal, but I can't handle when something on a plane is not just right.

I am not going to break the engine down to fix this. It was just done 370 hrs ago.

Sense the oil consumption is unchanged, I may be pouting about something that's not that big of a deal.

Cody, 

Have the engine completely cleaned, then get some Magnaflux developer or in a pinch, use some spray athletes foot powder and spray it all over the suspected area. Then do a 5 minute hard run of the engine. Your source will be revealed.

Make sure you include the oil return lines. #2 on a IO360 likes to rub against some Scat tubing and a small pin hole can develop.

Good luck, but it shouldn't be too hard to find.

[Marauder]

It appears that I have a cylinder base O-ring oil leak. I noticed more oil leaking from the engine lately and after doing some cleaning I was able to see the following. I plan on removing the cylinder and putting a new O-ring on it. We torqued the bolts at annual a month ago but no luck.

I began noticing leaks here last year. My engine has around 900 hours. How many on your's? Sent from my iPad using Tapatalk

[Marauder]

Cody,

Have the engine completely cleaned, then get some Magnaflux developer or in a pinch, use some spray athletes foot powder and spray it all over the suspected area. Then do a 5 minute hard run of the engine. Your source will be revealed.

Make sure you include the oil return lines. #2 on a IO360 likes to rub against some Scat tubing and a small pin hole can develop.

Good luck, but it shouldn't be too hard to find.

The oil returns line on my plane were replaced at the annual this year for exactly this reason.

Sent from my iPad using Tapatalk

[DaV8or]

It appears that I have a cylinder base O-ring oil leak.  I noticed more oil leaking from the engine lately and after doing some cleaning I was able to see the following.  I plan on removing the cylinder and putting a new O-ring on it.  We torqued the bolts at annual a month ago but no luck.

 

I have a cylinder base leak too, but not as bad as yours. Mine just seems to mist out under pressure when the engine is running. It doesn't drip, or leave puddles. I'm just going to live with mine as long as I can. I would love to see pictures of yours when it's apart. I'd like to have a better understanding of how this seal fails. Thanks!

[DaV8or]

I have maintained and operated 4 different Lycoming IO-360 engines for over 4000 hours all together. I'm not saying that it is impossible to make this engine leak free, but I've never seen it.

 

I kid you not, when I bought my plane, the engine didn't leak a drop. It was dry everywhere. It had about 400 hours on the engine at that time I think. I was very pleased to have a non leaking airplane engine because I knew that was rare.

 

Well, those new owner good times only lasted maybe 20-30 hours. I have been chasing leaks ever since. My rule now is, if the oil never makes it to the hangar floor, I'm OK with it.

[N601RX]

It may be leaking around the through bolt instead of the cylinder oring. If the case hasn't been modified to use an oring around the throughbolt the only seal is the interference fit between the bolt and case. I think I still have the oversized throughbolts that we removed from my engine when we overhauled it. I had my case converted to use hollow dowels and orings.

[Cody Stallings]

It turned out being the through bolt. Had lots of damage from yrs of driving them in an out. My A&P reamed it an installed the oversized. It's dry as can be........ For now!

[1964-M20E]

It turned out being the through bolt. Had lots of damage from yrs of driving them in an out. My A&P reamed it an installed the oversized. It's dry as can be........ For now!

Well it looks like I need to do the same.

 

[Cody Stallings]

You have a place that you trust that can put the oversized stud in?

[1964-M20E]

Working with my MX we just tried pulling the cylinder and changing the o-ring but it appears not to have helped much.

 

I would do it with my MX unless you know if something that  is a got ya?

[1964-M20E]

Where did you get the reamer?