Has anyone experience rusty bearings
in their Saito four stroke engine's.
What is the cause,moisture?
in their Saito four stroke engine's.
What is the cause,moisture?
Paul Allen
rusty bearings
Stuka Stunt Main Forum · 5 of 5 known posts recovered
Rusty Bearings are a common problem in 4 stroke engines where the crankcase is not scavanged. One of the by-products of combustion is nitric acid from the breakdown of the nitro in the fuel. This plus the moisture from combustion gets past the piston and into the bottom of the engine where there is nowhere for it to escape thus causing corrosion. I have seen it frequently in RC engines and have had to replace bearing in several friends 4 stroke engines in the past before we understood how to prevent this happening.
Flushing out the engine after use with a suitable oil should stop it happening again. In an earlier post a suggestion of air tool oil was made for this purpose and I guess that this would be the way to go.
This bearing corrosion can occur in 2 stroke engines if they are left unused for some time without flushing and oiling.
Regards
Mike
do you think you could install a breather vent for the crankcase, sorta like pcv valves on auto engines?
"sacrifices must be made" Otto Lillienthal
Most of the 4 stroke engines that I have seen have a breather of some sort but this doesn't stop stuff building up in the bottom of the engine. I squirt some oil in to my Laser 90 through the little breather on the backplate. SOme of the latest RC 4 stroke competition engins use the crankcase as a supercharging pump and pass the mixture through the crankcase where it is compressed and fed to a plenum chamber before the induction cycle.
Regards
Mike
The Saito 56 engines I use are pretty easy. If I'm flying pretty regularly, I don't worry about it. Once the season is over, or I don't plan to use the engine for awhile, I shoot Marvel Air Tool Oil into the intake and spin the engine for a bit. Then I squirt it into the bottom end vent and do the same. I then put the engine in a Ziplock bag, squirt some more airtool oil in and seal the bag.
Haven't had a problem with berings.
I don't worry about it while it's being regularly used because, at least for me, I get a huge amount of oil out of the case vent when flying. I mean really a lot. I use a castor/synthetic 50/50 blend fuel (24% oil) and feel there is plenty of oil in the case between sessions.
But that's just me.