Over tightening the prop is not a typical cause for bearing failure. Usually bearing failure comes from dirt or debris being injested into the engine while running. If you fly on grass fields or dirt runways...the dirt and crud will get into the engine. If you turn the prop slowly and it feels rough at all the bearing is going bad. It is time to service the engine and repalce the bearing. Flying on grass and or dirt fields especially if the dirt is fine and sandy you may need to replace the bearings in your engines as often as once a year. Depending on the amount you fly ti might be more often.


Another issue is rust, usually because of the fuel you choose as the oil doesn't protect when the enigne is not running. I have had really good luckw ith Cool Power fuel and no rusty bearings. Now I live in a dry climate AZ and before that Denver Colorado again dry. I would suggest that you store your models inside where the temps don't get really cold. If you store ina garage that gets to freezing or below I think you make have more trouble with rusty bearings than if you always keep in the house at 68-75degs. Some enviroments like say coast line areas where the air is very humid, it might be a good idea to run the engine dry and then use some oil to lubricate it for storage over the winter. When not running or ina model I pull the engine, put a small amount of synthetic oil non petroleum based stuff. Mobile 1 synthetic 0W-20 is good for this only use just a little bit. Then I wrap the engine up in a plastic zip lock style bag. This way it stays away from the moister in the air. Me being in Arizona I don't have this problem as much as say a guy in Florida or Seatle might have.


The next thing that can cause bearing failures is lack of good lubrication and or running the engine lean. This can cause a failure too. Your fuel could be a cause.

Then there are just some cases where a bearing will fail...usually if this happens and the bearing just goes it usually is when the engine is new.

Typical bearing changes for me is about 300flights. I change them out for good measure and don't have too many problems with bearings. If its gets crashed it gets a new set of bearings becasue it likely flat spotted or tweaked the bearing.

I tighten my props pretty good as well, and always you have to use a double jam nut type of prop nut. This is for safety on all the 4 stroke engines.


I hope this helps answer some of the questiosn about bearings. If you would like to discuss your fuel or something offline I'm good for that just PM me or send an email.

Troy Newman
Team YS