Pirep on Lycoming Case Leak Repair Technique

[Paul Millner]

Wow,
It’s always something, isn’t it? After 16 years and 1500 hours, I need to replace an exhaust valve system part on my IO-550N. At least the valves themselves are holding up and all 6 cylinders looked good as of Wednesday’s borescope. Like everything engine, all I’ll say is it has behaved…so far. Next time it runs could always be something else.

Hope this all isn’t too painful for you.

Warm regards,
Andy

Thanks Andy. Not painful... but the reassembly continues. There's been a few supply chain problems, but the bigger problem has been my busy schedule! Winding up a five week "introduction to Europe" trip with the great-nephew. Then I'll be home 5 days before it's time to head to Durden's Cadillac floatplane extravaganza, Oshkosh, and a week in the 1,000 Islands (address for sympathy cards available on request).

I've missed lots of hangar time consulting for AOPA and FAA on unleaded avgas, too... both interesting organizations to see from the inside after all these decades!

Paul

[A. Niemyer]

Wow,
It’s always something, isn’t it? After 16 years and 1500 hours, I need to replace an exhaust valve system part on my IO-550N. At least the valves themselves are holding up and all 6 cylinders looked good as of Wednesday’s borescope. Like everything engine, all I’ll say is it has behaved…so far. Next time it runs could always be something else.

Hope this all isn’t too painful for you.

Warm regards,
Andy

[Paul Millner]

OK, end of test after almost three years... no leak, but the engine needed to come apart for prop strike inspection. We found case fretting and a flat cam lobe, but no prop strike damage...

[Tom Charlton]

Just changed all four cylinders at annual... 18 months since the fix. Engine still dry!

Hi Paul,
Good to hear that!
I’ve kept this innovative solution in mind ever since you’d first posted. Don’t see why it wouldn’t work on a Continental also should the need arise.

Regards,
Tom Charlton

[Paul Millner]

Just changed all four cylinders at annual... 18 months since the fix. Engine still dry!

paul

[Gary_Risley]

Great info. I am forwarding this to my A&P who is working on someone else's Lycoming with this problem.

[Jeff Hartmann]

I was wondering if some of the locktite could get into an oil passage, or did none of it go all the way through the seam?

[Ralph Jones]

It would appear that your technique sucks...;-)

[Paul Millner]

Wow!

Still dry, but now we’re changing a cylinder... see if we screw it up!

Paul

[John O'Shaughnessy [FCM]]

Wow!

[Paul Millner]

Folks,

As recommended by Ed Kollin of Camguard, and further amplified by CFO member Vince Endter who learned of this technique during his recent Lycoming engine school in Williamsport, we put a vacuum on the case via an industrial vacuum duct-taped to the oil filler tube.

We then removed the case-half bolts along the spine of the engine where we had a BAD oil leak (1/2 quart per hour). Then, the area, including the bolt holes and along the spine, were cleaned with MEK to get rid of any oil.

We then used kind-of-pricey Loctite 290 to seal the area. Applying the Loctite to the spine, we could see it wicking down past the open bolt holes. We made roughly three passes with the Loctite, then turned off the vacuum cleaner. We then reinstalled the hardware, and left the plane to sit overnight.

On ground run up, and now after a dozen hours or so of flight operation, the entire area is as dry as a new engine. Amazingly good results! Thank you Ed, Vince, and Lycoming for letting us know about this new technique... we were really surprised by how well it worked!

I'll keep you advised as time progresses, but for now, I'm going flying!

Paul

Pirep on Lycoming Case Leak Repair Technique