My brother gave me a OS MAX 15 III with little use, if any,  and I have a few questions about it.

I ran the engine on the bench and noticed it is leaking between the Steel Fins and the Crank Case, is that normal for this engine?

I noticed that there is  only 3 screws that go all the way from the Head  down to the aluminum crank case to hold the Steel Fin/Liner and 3 screws that only fix the head to steel fins, is that how it is

The conrod does not have a bronze bushing and I am afraid it wear down quickly, is there a better conrod available out there that is a match for this engine?

Will it need Teflon pads for the wrist pin like the OS MAX 35S?


Thanks,

Martin

Hi Paul,

Thank you for your input. Did you notice in your engines any fuel leaking like I have described?

I have been looking for one of this Engines for some time and my Brother was kind to give me one. It is one of the lightest .15 I know and I plan to put to good use. Have a  few projects in mind for it:  Tiny, Nobler Jr. or Spitfire MK14 AeroFlite.

Martin

The FP/LA venturis will not fit.  The OD is .391".
The Max III needs a .351" OD.  You will probably need to make something out of alumumun, nylon, or even hardwood.  The are no beauty points.  The air only cares about the ID.

Leakage is NOT OK.  It should be a tight seal.  A little leakage is the step before totally blowing out the gasket, which woiuld be a bad thing.  

One big problem with those blackfin engines was that, once run, the gasket becomes fused in place and you can't take it apart with destroying and replacing the gasket.  Since you can't get a new gasket, it's become a bigger issue.  So tighten it well and hope it doesn't blow.

bummer!

replacing this gasket shouldn't be that hard. The engine ran once on the bench and when I saw leaking fuel I stop it.

I am thinking to disassemble the engine and use 0.012 aluminum sheet to make a replacement gasket and seal with high temperature silicone. Unless there is a better way to do this.

I have refurbished several engines but this one is a bit different construction. Some advise would be greatly appreciated.

    Might want to measure the piston depth at TDC, so you can get the cylinder back to the same place with the new gasket. There's not a lot of pressure on this gasket, so I would suggest paper or rubberized paper.
 
      Brett

Not to worry.

Just measure the deck height and head depth when you put it back together and make sure you have a reasonable amount of clearance.  Like maybe .010"