Originally Posted by mrgsr
I would like to start a thread about engine bearings and mainetenance.
The first question i have is how often should engine bearings be replaced? (this is referring to .12 on road nitro racing)
How do we check or what signs tells us our bearings need to be replaced.
I'd say for sure no longer than 10 hrs (at an average rpm of 35,000 for 10 hrs that is like 21,000,000 revolutions on that poor little bearing!!)
I like to change mine every 5hrs. Cheap enough insurance to make sure your engine is running it's best.
I also change the rod at 5hrs wether it needs it or not, so that may just be me.
The previous post is very good advise for signs of wear. Primarily lateral movement or looseness of the race, then check for gritty feel (although this will usually mean dirt or contaminants like metal from glow plug element, piston material, material from crankcase caused from crank rubbing etc.) All of which are very bad!
Make sure to use a fixture or oven to install your new bearings as one time with a hammer (very likely to install bearing crooked) and your crankcase WILL be junk and will need replacement. USE A FIXTURE!!!
Slightly loose bearing fitment to the crankcase can be fixed with red locktite on outer race surface when installing new bearing (however if this is used the oven install technique is no longer an option!) USE A FIXTURE!!
Thats pretty much all I have to say about that...