What causes liner peeling on the LA 46.

Lean runs ,crappy fuel , dodgy manufacturing. Pick one - or all of the above .

Brad

     This answer pretty much covers it. My opinion is that it was a cheap nickel type material applied really thin and then started to come loose when the engine over heats and/or runs too lean too long. The only case of this I have experienced, oddly enough, was on a OS .32F that had the coating come loos on the outside of the liner below the exhaust. Flakes got down into the rear bearing, and you shoulda heard the noises THAT made!! . I took the engine apart, polished the area down a bit to feather the edges of the coating, and put it back together. The piston/liner fit was still very good, and the affected area really didn't make any contact with the case, so I figured why not run it . Replacement liners are not that easy to find. The LA .46s I have been running have shown no sign of this, and I think if you chose props carefully, and watch you oil content to avoid too little or too much, I don't think you will have much problem.
   Type at you later,
   Dan McEntee

Thanks for the reply's, the motor in question was an RC version and had little use and no lean runs, it was gummed up and I stripped it down for a clean out, very thin liner in the LA 46. I have a Gardner P/L, guess it now has a home.

Someone told me the LA engines had a bad run of liner coatings at one time so, some are good and some not good. I had one or two go bad but others that ran good until they wore through to the brass. One thing to keep an eye on are the teflon pads on the wrist pin. Should be replaced if you're putting in a new P/L.

MM    

My understanding is that, around the time of the VF's, the Japanese govt banned the use of chrome due to the noxious chemicals required so nickel was next best replacement. An advantage was that the brass liner could be finish machined and only an extremely thin coating of nickel was needed and no further finish machining was needed. However I suspect if there was any trace of contamination on the liner then the nickel may not have been deposited securely to the brass. This is also why the liners are plated all over so there's no discontinuity in the plating. The best engines I've come across with nickel plating is the Enya CXR series which uses a nickel plated silicon carbide composite, usually called Nikasil but that's a trademarked name .

I have had some os liners look pretty gnarly and still ran ok .  I have a os 25 sf that has a big chunk of the nickel  slightly above the exhaust and it still runs fine. If I had not taken the head off I would not have known anything about it.  I had one 46fx that was being run on 50%nitro on a carrier model. Got away with it for several contest and then all of the sudden it started feeling quite crunchy.  So much for that engine.

Brett
        You are right, last time the motor ran it was fine and the piston looks good no damage.
Motor was gummed up and I like to check the wrist pin is free, which in this motor is was not.