ORIGINAL: wcmorrison
Six gallons is about 12 hours of flying time at burning one ounce per minute. I'd say it is worn out. I speculate that the liner did not peel but just wore away. That much time on an engine is a lot. But then I also would not use Coo Power even with extra added Castor oil.
Good luck,
Chip
I know of some engines that are just getting nicely broken in by the 6 gallon mark.
I run the snot out of engines, a lot for testing blends. There is not one OS nickle plated engine (including the 46AX & 55AX) that I have not been able to peel the liner out of. Most of the time if its going to happen, it will be in the first gallon or so, and frequently on the first few tanks. I have never peeled an ABN Thunder Tiger or Webra.
OS has not perfected the ABL/ABN process and really should look at the way TT or Webra do it. There are some that say its a small percentage of engines that peel but consider that a few companies over the years (Just Engines, Saturn Hobbies and one other) have made chrome plated sleeves specificaly for the 46FX engines and no brands. Even the Late George Aldrich plated over 100 peeled 46FX liners before he died.
I agree with XJet and a couple others, well designed and manufactured ABN engines will easily last 50+ gallons and I've had several go over the hundred gallon mark.