Oil Leak Fix Story

Dave_G

Well-Known Member
I know this doesn't have much to do with off road stuff but I thought this might spark some ingenuity in some folks for future reference.

A few days ago I was flying my airplane back from Santa Maria to Rialto when I encountered a slight inflight problem. As I was level at 9500' I started to see little specks of something on the windshield that soon became streaks of oil. As most can guess, oil on the windshield of an airplane is NOT a good sign and usually generates a pucker factor that exceeds the normal scale. A quick PAN call to SoCal controllers gave me vectors to several nearby airports but the GPS said I was only 17 minutes from home so I elected to continue to Rialto based on the (flow rate ;-) and landed safely.

After landing and pushing the airplane back into the hangar I removed the cowling to try to find the source of the oil leak. I sprayed the engine down with AVGAS and rolled it outside and ran the engine up to try and see where the oil was coming from. Low and behold it was coming from the centerline case seam near the back accessory cover. Now, for those that are not familiar with a Lycoming O-360 engine it is almost just like a Volkswagen engine. Flat pancake style four cylinger air cooled motor.

On an aircraft engine like mine the case halves are sealed together with a single silk thread between the case halves. This thread had apparently broken and the only remedy was to split the case halves and reseal it. Well, that costs about $12K with an overhaul and homey wasn't about to part with that kind of money so I enlisted the help of a really good A&P mechanic who said he could fix it for a lot less.

The end result was that we connected a vacuum pump to the engine and plugged the breather line to generate a vacuum enviroment in the engine case. This caused the the leaking case split line to leak from the outside in. While it was sucking air we applied a small line of super glue ( Zap-A Gap to be exact..) to the case split line and the vacuum sucked it into the case halves sealing them. We then applied a thin film of fuel tank sealer over it for good measure.

AND IT WORKED!!

Just goes to show that a little ingenuity and experience goes a long way in solving a problem that is not as bad as you think it is.

Just thought I'd share that kind of a fix......

Dave

"I started out with nothing and still have most of it left"
 

ACID_RAIN28

Well-Known Member
dully noted, I would have just JB welded it, but that is me.

"Everything you do is triggered by an emotion of either desire or fear."
 

Greg

Well-Known Member
You should've just put Pro-Long oil tratment in it then drained all the oil and run it like that, it works for them in the infomercials.

Greg
 

Dave_G

Well-Known Member
Re:"I would have just JB welded it, but that is me."

Actually, the fuel tank sealer is mean stuff. It's also very plyable to put up with all the expansion and contraction when the engine warms up and cools down.

Dave

"I started out with nothing and still have most of it left"
 

tedmales

Well-Known Member
there are a series of events that lead to catastrophe and i do believe that you might have created one. i do not blame you for not wanting to spend the big bucks to get it fixed right, but superglue is something you use to get yourself off of the side of the road, not a repair for an airplane. i would not sign off on that plane to save my life.good luck. hope no faa guys read this thread.

life is too short to be small
 

BlueCoyote

Well-Known Member
Superglue is also good for fixiing seeping rivits on wet wings.
As for the case leak we used to use a old style can opener to scribe the seam, then a thin bead of fuel tank sealer.
I might be a bit more concerned as how that much oil was being puked - sounds like a lot of case pressure. Might be a good idea to check the breather (since aircraft engines do not have PCV valves) and front crank seal as well. As an added precaution we used to slit the breather hose about 2" to allow for pressure release in the event the breather plugged up, the case pressure would not blow the front seal (catastrophic).
Glad you got back safley

Who are you calling Coyote ugly?
84 Toyota p/u Rokrawlr
86 4rnr
84 Toyota 7s Project
 

Dave_G

Well-Known Member
RE:"sounds like a lot of case pressure. Might be a good idea to check the breather"

It's not a case of excess pressure in the crank case at all. It has to do with the negative pressure generated on the aft side of the cowl baffling that actually sucks oil from the seam. If you run the engine on the ground with the cowling off it won't leak without the negative pressure. It is a very common problem with Lycoming and Continental engines.

Dave

"I started out with nothing and still have most of it left"
 

Dave_G

Well-Known Member
Re:"i would not sign off on that plane to save my life.good luck. hope no faa guys read this thread."

Ted,
The FAA guys can read all they want. I operate under an experimental type certificate and since I'm the builder of the airplane I don't need a signature from an IA orAP. As it turns out the type of repair that was done is a very common method and is even approved on certificated factory airplanes.

Dave

"I started out with nothing and still have most of it left"
 

ACID_RAIN28

Well-Known Member
I wasn't serious about the JB, Lets see a pic of the plane, and where did you get your flight training?

"Everything you do is triggered by an emotion of either desire or fear."
 

FABRICATOR

Well-Known Member
Actually that's very similar to what fleets and dealers do with star cracks on windshields from rock impacts. They use a suction cup and vacuum pump over the crack and pump it down. Then they release a clear epoxy into the vacuum and it gets sucked into the crack. It only works on fresh star cracks and it almost makes the crack invisible.

<font color=blue>"A Ship in the harbor is safe, but that's not what ships are built for"</font color=blue>
 

tedmales

Well-Known Member
nice plane. i did not know it was a homebuilt, been looking into a hp homebuilt, but no room, and not enough money to be able to do it an use it. stuck with the local 172, for now.

life is too short to be small
 

Dave_G

Well-Known Member
That be it. ;-)

Dave

"I started out with nothing and still have most of it left"
 

ntsqd

Well-Known Member
Dave, there is a Lock-tite or Permatex gasket product that is intended to wick into holes and seal them off. Not sure of the name or number, but it would work roughly the same as the CA did only would probably stay more pliable after curing.

TS

I used to swerve around my halucinations, now I drive right thru them.
 

Dave_G

Well-Known Member
I'm sure it's probably made by Lock-tite. Is there anything they dont make? ;-) I think the sealant you are thinking about is Lock-tites "Wick and Seal??"

I spent the day making custom O-rings for the new Herbst transmission's with Lock-tite's O-ring splicing kit. Really a nice kit except for the glueing fixture. It's made from plastic and the O-rings stick to it with the glue but I made a new fixture out of PTFE and solved that problem.

Dave

"I started out with nothing and still have most of it left"
 

michael_loomis

Well-Known Member
loctite / permatex = same company
 

ntsqd

Well-Known Member
Not any more. I understand Lock-tite & Permatex have had a divorce of some sort.

O-ring gluing fixture ? When I was working in ultra high vacuum I made a lot of O-rings. I just used my fingers. Square cuts (scalpels are the best for this), a drop of CA, and hold for a bit. Then I used a fine sandpaper type nail file to dress the down the glue bulge. Did the same thing on very rare occasions while prototyping something at wilwood.

TS

I used to swerve around my halucinations, now I drive right thru them.
 

CRAIG_HALL

Well-Known Member
Off subject,but thats a clean piper cub in the backround. My uncle has one, very cool plane. Anybody go to the riverside airshow a couple weeks ago? My uncle flys with the airforce in thier "heritage flight"with his mustang.
 

CRAIG_HALL

Well-Known Member
farther off topic but hers his plane
photo is from airforce site
 

Dave_G

Well-Known Member
RE: "O-ring gluing fixture ? "

Yea, it's nothing more than a plastic V-block. Really basic. Just allows you to get the ends aligned correctly during the glueing process. They also give you a clean up solvent to remove the excess glue and a sealer to protect the joint from moisture. Apparently moisture will degrade the CA so they warn you to brush it on before placing the O-ring into service.

Also,
Attached is a pic of my "Jed Clampet" repair on the engine case. ;-)

Dave

"I started out with nothing and still have most of it left"
 

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