Varnish or Rust?
12-30-2003, 07:32 PM
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Varnish or Rust?
I opened my engine for cleaning prior to putting it away for the whole season. I should have done this in October after my last flight of, but this last week was when I finally got around to it.
I do use after-run oil, and the fuel I use has a mixture of castor and synthetic oils. The only affected parts of the engine are are crankshaft, the rear bearing, and the carburator barrel. Thing is from searching other posts I gathered that the crankshaft/rear bearing might only be varnished from the castor oil and reddish dye used in the fuel, but it won't go away from rubbing with a Q-tip (or not much). Turning the engine over is on the other hand very smooth, I don't feel any sort of grinding or sound.
As for carburator barrel, It can't be seen (very well) from the photos, but the only affected area is what was left exposed to air. From this I mean that the throttle arm was left at low idle when I left the engine sitting in the shop. Now, if I close the throttle completely and look at the carburator barrel that's showing, I can see a small cresent (what was hidden from view by the barrel being partially open) that's completely unaffected by the rust-colored splotches.
Same as the crankshaft, when moving the throttle arm, there is no grinding sound and everything moves very smoothly.
So what is it, and what can I do (Sorry for the quality of the photos).
edit: I should have added that the engine is a 46fx, and I've run 3 gallons of fuel though it (my first season).
I do use after-run oil, and the fuel I use has a mixture of castor and synthetic oils. The only affected parts of the engine are are crankshaft, the rear bearing, and the carburator barrel. Thing is from searching other posts I gathered that the crankshaft/rear bearing might only be varnished from the castor oil and reddish dye used in the fuel, but it won't go away from rubbing with a Q-tip (or not much). Turning the engine over is on the other hand very smooth, I don't feel any sort of grinding or sound.
As for carburator barrel, It can't be seen (very well) from the photos, but the only affected area is what was left exposed to air. From this I mean that the throttle arm was left at low idle when I left the engine sitting in the shop. Now, if I close the throttle completely and look at the carburator barrel that's showing, I can see a small cresent (what was hidden from view by the barrel being partially open) that's completely unaffected by the rust-colored splotches.
Same as the crankshaft, when moving the throttle arm, there is no grinding sound and everything moves very smoothly.
So what is it, and what can I do (Sorry for the quality of the photos).
edit: I should have added that the engine is a 46fx, and I've run 3 gallons of fuel though it (my first season).
12-31-2003, 12:04 PM
#2
My Feedback: (11)
RE: Varnish or Rust?
Most likely, the discoloration is staining by the fuel and after-run oil. The engine's heat will cause deposits to form, and that's known as "varnsh". It becomes baked onto the surfaces, which is why you couldn't remove it with a Q-tip. You'd have to use a scrubbing pad or steel wool to remove it. Since your bearings are smooth, it's not corrosion, which would make them turn roughly and be flaky as well.
Over time, varnish buildup will close the engine's tolerances and make it tight. It will tend to run hot when that happens.
Over time, varnish buildup will close the engine's tolerances and make it tight. It will tend to run hot when that happens.
