ArtVandelay Posted February 22, 2019 Report Share Posted February 22, 2019 Engine sent in for overhaul, crack (by alternator) was discovered, probably source of my persistent oil leak: Is this common for Lycomings? Tom Quote Link to comment Share on other sites More sharing options...
Runway37 Posted February 22, 2019 Report Share Posted February 22, 2019 Sorry to hear about your cracked case. My IO 360 (A1A ?) case cracked and was deemed "not weldable" by someone (happened in 1978 or so). It presented as a small oil leak on my 1964 M20E. I can't remember if just one half or both halves were replaced but I ended up doing a major overhaul. Good luck, I hope you can get it welded. A supporter though it doesn't show as such Quote Link to comment Share on other sites More sharing options...
carusoam Posted February 22, 2019 Report Share Posted February 22, 2019 Tom, Cracks are not very common... But there is one location that is most common if it is to occur... One of the cylinder locations... searching on the word case crack will probably find the details... PP thoughts, not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Shadrach Posted February 22, 2019 Report Share Posted February 22, 2019 I had a similar crack on our IO360 A1A. It was on the passenger side case half. It started at the outside of the bolt boss and propagated from there into the case. It was the first bolt boss aft of the Gen/Alt mount pad. It leaked profusely. Case with overhauled and reinforced by Crankcase Services of Tulsa, OK. That was nine years ago. No problems. Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted February 22, 2019 Author Report Share Posted February 22, 2019 It wasn’t repairable.Tom 2 Quote Link to comment Share on other sites More sharing options...
bradp Posted February 22, 2019 Report Share Posted February 22, 2019 Places I’ve heard of having cracks (haven’t experienced one yet) are starter mounting pad, cylinder flange, engine hoist part. Haven’t heard of a alternator crack yet but I’m no A&P. Quote Link to comment Share on other sites More sharing options...
Shadrach Posted February 23, 2019 Report Share Posted February 23, 2019 5 hours ago, ArtVandelay said: It wasn’t repairable. Tom It may have been had it been diagnosed earlier. When did the “persistent” leak show up? Ours was dropping oil right on the exhaust so it was obvious at shut down. The engine maybe had 2hrs between first noticing a leak and diagnosing the crack. Engine was pulled immediately. Quote Link to comment Share on other sites More sharing options...
Shadrach Posted February 23, 2019 Report Share Posted February 23, 2019 (edited) 9 hours ago, bradp said: Places I’ve heard of having cracks (haven’t experienced one yet) are starter mounting pad, cylinder flange, engine hoist part. Haven’t heard of a alternator crack yet but I’m no A&P. There are two small pads machined into the case fot the gen/alt brackets. My crack occurred just aft of the aft gen pad. In the pic below you can see the rear gen mount is still attached. The crack is identified with red marker. It started on the outer edge of the parting flange and propagated inward. The cost to clean, repair and overhaul the case was $800.00 in 2010. Edited February 23, 2019 by Shadrach 1 Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted February 23, 2019 Author Report Share Posted February 23, 2019 It may have been had it been diagnosed earlier. When did the “persistent” leak show up? Ours was dropping oil right on the exhaust so it was obvious at shut down. The engine maybe had 2hrs between first noticing a leak and diagnosing the crack. Engine was pulled immediately. It’s been a while, but everyone said that’s normal. 3 different APs looked at during annual and didn’t see it.My alternator wasn’t standard Prestolite, was a larger (+2lbs), I believe added because of extra load from wing lights mod.Tom Quote Link to comment Share on other sites More sharing options...
Shadrach Posted February 23, 2019 Report Share Posted February 23, 2019 (edited) 3 hours ago, ArtVandelay said: It’s been a while, but everyone said that’s normal. 3 different APs looked at during annual and didn’t see it. My alternator wasn’t standard Prestolite, was a larger (+2lbs), I believe added because of extra load from wing lights mod. Tom Given the location of the crack, I am surprised that your muffler wasn’t coated with a layer of cooked on oil. General Aviation engines leak, but that does not mean those leaks should not be addressed. My engine is oil tight at this time. Those A&Ps did you no favors by not investigating.. Edited February 23, 2019 by Shadrach Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted February 23, 2019 Author Report Share Posted February 23, 2019 Giveen the location of the crack, I am surprised that your muffler wasnt coated with a layer of cooked on oil. General Aciation engines leak, but that’s does not mean tear those leaks should not be addressed. My engine is oil tight at this time. Those A&Ps did you no favors by not investigating.. I had oil on the muffler in one spot where there is an indentation, but the turbulence of the air flow resulted in oil everywhere on the bottom, I’m guessing the crack hidden. I did send the pictures to my current AP.Tom Quote Link to comment Share on other sites More sharing options...
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