Loctite to seal crankcase leaks

[PeterNSteinmetz]

So the O-360 on my Cardinal has developed a slow leak on the aft top side. I have heard that one can clean thoroughly, apply vacuum to the crankcase, and then apply LocTite 290 and get a good seal until next overhaul.

My mechanic is a bit skeptical however. Does anyone know of more official advice on this being a reasonable procedure?

 

[rotorwrench]

Does anyone know of more official advice on this being a reasonable procedure?

A number of years ago this technique made the rounds that was supposedly taught at Lycoming field maintenance training. Given the leak you mention was a "feature" of some engines it was "plausible." However, I and others have never seen any official docs on this which does go against current Lycoming guidance on case half sealants. As I recall you also need to loosen/remove the case-half hardware in addition to the items you mention before applying the Loctite. A big question was how does one control the depth of the Loctite as it gets drawn into the split? Regardless, I had better than 50% success by using ProSeal over the top of the split line once the area was properly prepped and all engine case hardware was torque checked to include the cylinder through bolts.