RE: OS 65AX ABL
 

I confess, I almost never put in afterrun oil in my engines and I even have it in my field box. I have been running the same tt 46 engine without any maintenance that I bought in 1995. I did have a few long years in between actively flying but the engine has well over 6 galllons of fuel through it and has only had about 3 glow plugs ever put into it. It has only started seeing after run oil in the last year and only about 5% of the times I have flown. If I think I am going to fly in less than a week I do not oil it. I am also still using the original dreaded steel caged bearings it came with. It might be different in a more humid climate but in my climate in Montana, running from 0 F to 90 F weather I have not had many problems with bearings in any of my engines. I am thinking that with as new of an engine it was, it was a manufacturing defect.

RE: OS 65AX ABL
 

Donald Drew,

I have replaced a lot of bearings in both 2-stroke and 4-stroke engines. All the info you have received from others here has merit. The one thing I have observed is that the manufacturers use steel bearings. These are more susceptible to rust. Steel bearings are attacked by the nitro fuel, humidity, and long storage periods in basements or garages. When replacing the bearings I always choose Stainless steel or ceramic bearings over steel. These resist rust and last longer. When bearings fail the engine works harder and idles poorly requiring frequent carb adjustments to try & smooth out performance. OS engines are well made and should last for years. From what you describe, it sounds like you are above average in your care for your OS 65AX. Therefore I am surprised to hear of so much damage reported by the serviceman. Bearing failure can easily be detected by rotating the crankshaft by hand. If there is any roughness you will feel it as you turn the shaft and you will know to replace the bearings. The cost to replace the bearings and cylinder liner, piston would probably be more or as much as replacing the engine completely. One final note you may wish to change fuel manufacturers and or use fuels with a castor/synthetic blend.

Sledge_78

RE: OS 65AX ABL
 

Nitro fuel does not attack bearings, it is not corrosive to the internals of  the engine, only the methanol is.

Can someone tell what are the correct Nachi bearing to buy for the OS 65AX engine?