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What A Nightmare!


alextstone

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Spoiler alert, this was a really bad dream, not reality.  I dreamt last night that during my routine inspection of the engine and accessories while changing the oil and filter, I found several cracks near two spark plugs in the cylinders. Although it did not happen, the thought led me to wonder if there is any data out there on the incidence of cylinder or case cracking.  Are there certain engines that are significantly more prone the the same and if so, why?  

Also, for those of you who have Bravo experience (Lycoming TIO-540-AF1B) it seems that every time I un-cowl the engine, I find a pesky oil leak at a fitting in an oil return line or exhaust valve guide oil line (not a bad dream, reality).  Is this common or am I just still running down consequences of past dormancy?

Alex

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20 minutes ago, alextstone said:

Spoiler alert, this was a really bad dream, not reality.  I dreamt last night that during my routine inspection of the engine and accessories while changing the oil and filter, I found several cracks near two spark plugs in the cylinders. Although it did not happen, the thought led me to wonder if there is any data out there on the incidence of cylinder or case cracking.  Are there certain engines that are significantly more prone the the same and if so, why?  

Also, for those of you who have Bravo experience (Lycoming TIO-540-AF1B) it seems that every time I un-cowl the engine, I find a pesky oil leak at a fitting in an oil return line or exhaust valve guide oil line (not a bad dream, reality).  Is this common or am I just still running down consequences of past dormancy?

Alex

I have the occasional oil return line leak although it’s so minor (bit of dried oil residue) it’s not enough to do something about.  After I bought my plane the valve guide oil line to #1 had a small leak.  It turned out that the washer needed to be changed in the fitting and it’s been dry ever since.

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2 hours ago, alextstone said:

Also, for those of you who have Bravo experience (Lycoming TIO-540-AF1B) it seems that every time I un-cowl the engine, I find a pesky oil leak at a fitting in an oil return line or exhaust valve guide oil line (not a bad dream, reality).  Is this common or am I just still running down consequences of past dormancy?

Probably a little bit of both. Every connection is a potential for a leak and with an oil line going to the head of every cylinder plus some more t-fittings there are a lot of opportunities for leaks. When we did the Bravo conversion on my engine on the first run-up oil was pouring out. One of the oil lines was not put on square and ruined the threads on the hose fitting. Thankfully I had another identical hose and that corrected it. At every oil change I make sure they are snug and my valve covers (with silicone gaskets) are snug. 

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Other than in between the exhaust port area fins, cylinder head cracks are rare on Lycomings. However, six cylinder wide deck Lycomings are known to develop cracks at lower forward stud on the #2 cylinder, and the upper forward stud of the #6 cylinder. Your nightmare can be focused on these areas.

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I've had the exhaust valve guide feed connectors leak twice (2&4, then #2 a year or so later), they just needed to be snugged up.   Just check them at the oil change.   Lycomings ooze oil from the crankcase split, so there will always be some on the belly.   Nothing other than that. 

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