Crazy or stupid? Oil leak revealed

[BDPetersen]

Hmmm. Which one of you is Heather?

[cliffy]

Old timers use Titeseal on gaskets :-)

There is one type of RTV that is designed for fuel and oil environments, ALL the others deteriorate on contact with either. 

[Mkruger2021]

On 6/4/2022 at 7:07 AM, A64Pilot said:

I like Copper Coat, very sticky, does help seal never hardens so it’s easy to remove. It and silk thread have worked well on case halves for me.

In my opinion silicone has no place on gaskets, the reason is because the way it reacts to fuel or oil, they soften it and it swells up.

However a thin layer of grease has always worked well for paper gaskets too for those adverse to any king of goo, and they have a point, good clean surfaces and properly installed you shouldn’t need anything, anything is really sort of a band aid unless the manufacturer specs something, just Copper Coat had worked so well for me especially on copper head gaskets on high performance motorcycle engines that I like it

A bit confused, so don’t use the paper gasket? Just copper seal and silk thread?

 

[Guest]

32 minutes ago, Mkruger2021 said:

A bit confused, so don’t use the paper gasket? Just copper seal and silk thread?

 

Aircraft engine case halves and a few other special places use sealant and a silk thread, almost everything else uses some form of paper gasket.

Clarence

[EricJ]

16 hours ago, Mkruger2021 said:

A bit confused, so don’t use the paper gasket? Just copper seal and silk thread?

 

Use what the overhaul manual or IPC says if you want to be legal.    That won't be silk thread on the sump interface.

[A64Pilot]

On 6/7/2022 at 7:08 PM, Mkruger2021 said:

A bit confused, so don’t use the paper gasket? Just copper seal and silk thread?

 

No, sorry case halves, they have no gasket, metal to metal as it needs to be a perfect tight fit, but metal to metal and they often seep, so someone likely before I was born used silk thread with sealant and it worked. To be honest I don’t know if it’s approved or not.

I think it may be like assembly lube, I use Lubriplate motor assembly grease, others use other things like STP, book I think says use motor oil.

Edited June 9, 2022 by A64Pilot

[A64Pilot]

On 6/8/2022 at 11:53 AM, EricJ said:

Use what the overhaul manual or IPC says if you want to be legal.    That won't be silk thread on the sump interface.

If you want to be legal and not leak, cause I’m not sure how well the silk thread thing would work here.

Lord no, follow the book always, if something seems incorrect give Lycoming help desk a call, they will help. Home brew remedies have caused real problems

This may be of interest

https://www.aviationpros.com/home/article/10387221/silk-thread-incorrect-use-can-lead-to-disaster

Edited June 9, 2022 by A64Pilot

[carusoam]

Expect that we still have silk thread between the case halves….

And when it leaks…. There is a small chance it can be fixed without having to split the case….

 

PP memory only, stuff I have read around here….

Best regards,

-a-

[1964-M20E]

7 hours ago, carusoam said:

Expect that we still have silk thread between the case halves….

And when it leaks…. There is a small chance it can be fixed without having to split the case….

 

PP memory only, stuff I have read around here….

Best regards,

-a-

curious how do you to attempt to stop an oil leak on case without split?

 

[A64Pilot]

37 minutes ago, 1964-M20E said:

curious how do you to attempt to stop an oil leak on case without split?

 

If your asking what I think you are, it’s possible to retorque ALL the bolts around the perimeter of the case, maybe one or two lost torque and that’s the leak.

In my opinion it’s worth a try. To get to all of the bolts may require removal of some baffling etc

[amillet]

Our original factory new engine developed a leak at the case half seam on the top somewhere around 1500 hours since new. The through bolts had loosened up, but retightening them did not completely stop the seap. The local A&P/IA applied some kind of gray sealant to the seam from the outside which stopped the leak.  (Until the engine started making some metal  at 1818 hours and was replaced with factory rebuilt)

[EricJ]

2 hours ago, 1964-M20E said:

curious how do you to attempt to stop an oil leak on case without split?

 

This is why you often see RTV on the seam.   It's usually a sign of kludgy maintenance.   Once in a while it apparently works.

There are some better ways already mentioned, like retorquing.

[cliffy]

Just last year I had a small leak develope top center. I found the case bolts had loosened. Retorqued them and the leak went away,

Now on the othe rhand if the leak doesn't go away decades ago I know of a small airline with TIO-540 Lycs that "repaired" the case leaks with 

5 minute epoxy. Worked great back then. 

As I noted a while back I know of only one formulation og RTV that is petroleum safe. All the others will deteriorate in the presence of oils and fuels. 

[EricJ]

2 hours ago, amillet said:

Our original factory new engine developed a leak at the case half seam on the top somewhere around 1500 hours since new. The through bolts had loosened up, but retightening them did not completely stop the seap. The local A&P/IA applied some kind of gray sealant to the seam from the outside which stopped the leak.  (Until the engine started making some metal  at 1818 hours and was replaced with factory rebuilt)

I wonder if the grey stuff was from an oyl-tite stick.   That stuff is pretty decent and might work well on a case seam that still leaked after re-torquing.  

[cliffy]

Used many "crayons" of leak stop sticks on Boeing 707s under wings with leaky rivits back in the late 60s  :-)

Some of them looked as if it was raining underneath- old tired 707s with C6 turbojets and water injection to get off the ground

[A64Pilot]

2 hours ago, EricJ said:

I wonder if the grey stuff was from an oyl-tite stick.   That stuff is pretty decent and might work well on a case seam that still leaked after re-torquing.  

I’d bet fuel tank sealant, we used it everywhere assembling the crop duster, it’s about the best “caulk” there is and takes paint well. Just don’t use it for things like a windshield install, because it will be nearly impossible to remove. It’s not legitimately a structural adhesive, but used on patches etc it sure acts like it is.

[vik]

I also had to pull the engine to fix a similar static leak from the oil sump gasket.

What I discovered was that somebody messed with the engine 8 years ago to change the oil pump impeller (there is an AD on that). They pulled the accessory case leaving the oil sump in. Sure enough, the oil sump gasket was ruined. The exposed part of the oil sump was poorly cleaned from the old gasket, leaving some scratches on the mating surface. The corresponding piece was cut from a new gasket and put in place. A new accessory case gasket was installed with some sealant.

The whole thing was probably executed with the engine in place. On a Mooney!!! That is how we get those static oil leaks.

I ended up pulling the engine, pulling the oil sump and accessory case, cleaning all mating surfaces. New gaskets and just a bit of a blue sealant to fill scratches in aluminum and where the accessory case and the oil sump gaskets meet.

Once you pull the engine, you want to paint the engine mount, replace the rubber vibration absorbers etc etc.

Have fan!

Vik

 

[Joe Hood]

Silk is what Lycoming still uses. RTV is an ugly fix. I've heard if you induce a vacuum inside the case, you can suck in a variant of Loctite to seal the case.

[BDPetersen]

On 6/15/2022 at 9:37 PM, vik said:

I also had to pull the engine to fix a similar static leak from the oil sump gasket.

What I discovered was that somebody messed with the engine 8 years ago to change the oil pump impeller (there is an AD on that). They pulled the accessory case leaving the oil sump in. Sure enough, the oil sump gasket was ruined. The exposed part of the oil sump was poorly cleaned from the old gasket, leaving some scratches on the mating surface. The corresponding piece was cut from a new gasket and put in place. A new accessory case gasket was installed with some sealant.

The whole thing was probably executed with the engine in place. On a Mooney!!! That is how we get those static oil leaks.

I ended up pulling the engine, pulling the oil sump and accessory case, cleaning all mating surfaces. New gaskets and just a bit of a blue sealant to fill scratches in aluminum and where the accessory case and the oil sump gaskets meet.

Once you pull the engine, you want to paint the engine mount, replace the rubber vibration absorbers etc etc.

Have fan!

Vik

 

Yep, that’s me all over again. Did I mention re hanging engine also sucks? AI and I spent most of 2 hrs just getting hose to fuel pump re connected. Building ship in a bottle stuff. 

[cliffy]

3 hours ago, BDPetersen said:

Yep, that’s me all over again. Did I mention re hanging engine also sucks? AI and I spent most of 2 hrs just getting hose to fuel pump re connected. Building ship in a bottle stuff. 

But once you learn  all the intricacies of Mooney maintenance it ain't that bad after all!   :-)  Just different. 

Sure you can't stand behind the engine like you can in a 172 but it can be worked on anyway. 

If it was easy everyone would do it. We're an exclusive club of those who work on Mooneys. Anybody can work on Cessna's :-) (looking down nose)

[A64Pilot]

On 6/10/2022 at 12:53 PM, cliffy said:

Some of them looked as if it was raining underneath- old tired 707s with C6 turbojets and water injection to get off the ground

I’ve loaded a few C-5’s at Hunter Army Airfield is Savannah, and it did in fact rain under those big wings from cold fuel, this rain was water condensation though

[cliffy]

3 minutes ago, A64Pilot said:

I’ve loaded a few C-5’s at Hunter Army Airfield is Savannah, and it did in fact rain under those big wings from cold fuel, this rain was water condensation though

Yes but I'm talking Jet A leaks :-)   Had lots of heavy frost underneath the wings after coming in with cold fuel in the tank to a high humidity airport.  

Flew with a C-5 driver once and he said it would (if not careful) push the tanker away with its bow wave in flight.

[A64Pilot]

Just now, cliffy said:

Yes but I'm talking Jet A leaks :-)   Had lots of heavy frost underneath the wings after coming in with cold fuel in the tank to a high humidity airport.  

Flew with a C-5 driver once and he said it would (if not careful) push the tanker away with its bow wave in flight.

I understand.

 Early 80’s like maybe 1983 we had an SR-71 make a precautionary landing at HAAF, came in over the Savannah Mall, middle of the day. Taxied off to the end of the runway to a building we called Sabre hall, MP’s closed perimeter road and of course it’s presence was denied, but you can’t mistake an SR-71. Thing that surprised me was I swear it had white tires.

Anyway about a day or two later a special fuel truck showed up and refueled it and it left in the middle of the night. We went down to Saber hall and you could see where it was from the fuel still on the asphalt. Thing must leak like a sieve.

[cliffy]

It was normal to put large drip pans underneath SR 71s as they were designed to leak They expanded so much with heat at altitude from air friction that they grew IIRC about 12 inches longer in fast flight. The fuel was in fact a special blend 'only used in the SRs

The "white" tires were actually silver in color molded into the tire I presume for heat rejection

If you have never seen it go look up the utube of the LA Speed Story  Find the full length version He has an American flag shirt on in the video. 

[N201MKTurbo]

On 6/15/2022 at 6:37 PM, vik said:

I also had to pull the engine to fix a similar static leak from the oil sump gasket.

What I discovered was that somebody messed with the engine 8 years ago to change the oil pump impeller (there is an AD on that). They pulled the accessory case leaving the oil sump in. Sure enough, the oil sump gasket was ruined. The exposed part of the oil sump was poorly cleaned from the old gasket, leaving some scratches on the mating surface. The corresponding piece was cut from a new gasket and put in place. A new accessory case gasket was installed with some sealant.

The whole thing was probably executed with the engine in place. On a Mooney!!! That is how we get those static oil leaks.

I ended up pulling the engine, pulling the oil sump and accessory case, cleaning all mating surfaces. New gaskets and just a bit of a blue sealant to fill scratches in aluminum and where the accessory case and the oil sump gaskets meet.

Once you pull the engine, you want to paint the engine mount, replace the rubber vibration absorbers etc etc.

Have fan!

Vik

 

I’ve done the procedure you mentioned with perfect results. It depends on how much care you use doing it. Trimming the gaskets perfectly is important. I usually put the tiniest bit of Permatex in the two corners where the three gaskets come together.