Engine care

James, I haven't used any after-run product in 20 years. I've only had one engine rust. It was a Como .51 that I left in the car trunk overnight on a muggy summer day. The bearings rusted immediately. Run your engine dry after the last flight of the day and store it in a climate-controlled place and it'll be fine. Dr.1 Driver "There's a Hun in the sun!"

It still wouldn't hurt a cotton-pickin' thing to drop a few drops of some fine lube down the carb... That engine is a bushed engine so there are no bearings to rust only the crankshaft.. but wot the heck?!?! ( old saying: an ounce of prevention is better than a pound of cure!)

It really urks me to buy a used engine that the previous owner NEVER did ANY after-run care: #1 run the fuel out...disconnect the fuel line and run every drop out. #2 IF you don't plan on running that engine for several days, put a few drops of SOME type of fine lube down the carb (3-1 oil, sewing machine oil, Automatic Transmission Oil...something). #3 If you aren't going to run the engine for longer periods DEFINITELY put some oil in it and turn it over several times! For 4-strokes, you have to get the oil in the lower end. NOT just the carb! There is a vent line from the lower end, push some oil in there and let it slosh around the bearings!

I MIGHT believe you if: You use NO nitro, Have no BALLbearingS and don't fly much!

ESPECIALLY with 4-strokes!

Alcohol alone absorbs moisture from the air like a SPONGE. Water & a little left-over Nitro and the steel in ballbearings will rust. If you use casteroil for an after-run....THAT's GOOD!

CONGRATULATIONS! You have just won the Lotto!! U R Very lucky, indeed!

ABSOLUTELY not necessary, when fuel with castor oil is used.

I have plain and ball engines, use 15% nitro, synthetic and castor mixed, never seen a bit of rust. Never a drop of after run oil.

I do not have any 4 strokes though.

This subject has been beat to death, so I'll be brief. I think with no alcohol in the engine (run dry) no water, plus the engine was shut down hot enough to boil it off. The next key is to keep it in climate control, so no condensation can develop.

How much alcohol is left in an engine that has been run dry and is about 200 degrees average? Not much I would bet. I think most rust comes from the lack of additive packages or unsuitable oils used in the fuel. The amount of nitro in the fuel also seems to not be a factor as I have engines that run 5% and others that run 50% nitro. Neither have rusted over three years storage in my garage in the UK. No after run oil has been in any of my engines.

Thanks, everyone, for the feedback (and discussion!).

Will run dry and put some fine lube in, I think...

James

OK! If you, of all people, a seller of ball bearings for model aircraft say that you don't use after run oil, and don't get any rust, I will accept it. But do you mind if I use a little after run oil? I am just too old and set in my ways...

BUT Morgans DID agree with ONE of my items! That is to run the engine dry!!

--bob

Me being a seller og bearings has nothing to do with debunking old wives tales. There are even people here that think a shielded bearing stops fuel leaking from the front of an engine and that if fuel is leaking, it is the bearing's fault!

Paul, You and I know, that the shaft must have sufficient play in the housing for the engine to run well, so it will leak oil if there are no provisions like oil reclaiming grooves. Having said that, some personal observation: Bearing seal construction varies, and some seals are designed to lightly touch the inner race. The MVVS gas engines partly are supplied with a one-sided lip seal in the front bearing which bears to the inner bearing race. I could not detect a manufacturing preference as to which side the seal lip should be. Fit the seal outside, so that no dirt can enter the bearing, and the engine mean positive crankcase pressure will press the lip seal open, and thus leak oil. This way the bearing is lubricated well, and the engine front will seep oil. The plane nose will get dirty. The oil reclaiming grooves cannot function well this way, because the lip seal prevents any back-flow Fit the bearing the other way around, and the seal will stop all outward gas/oil flow; the engine stays clean. IMHO, it also will prevent proper bearing lubrication that way, and may cause premature bearing failure. On top of that, the delicate ball races are exposed to the environment and may suffer dust ingress. But most important, the engine stays clean. Some fliers prefer that over longevity. (not I) It is always good if the engine user has choices isn't it?

I "usually" take the time to run them dry.

nope, seals The shielded bearings lack the rubber seal.

Pe,

The actual clearances in well made engines are very small. If there is enough crankcase ahead of the carb port, there is no need for grooves or seals as the oil film will do the trick. A lot of newer engine designs make for larger transfer ports as well as larger carb bores. This forced the carb forward on the crankcase. If the front of the crankcase and shaft aren't moved also, the engine will be more prone to excesive leakage. By and large, modern engines are fitted with single shielded bearings and leakage is an accepted fact. The usual amount is very small and never presents much of a problem.

Problems usually show up with engines that spew raw fuel and are hard to tune because of that. These engines can also suck air through the area at low throttle settings making shut down difficult. I stock double sealed front bearings for some problem engines. These bearings have a light synthetic channelling grease in them for permenent lubrication.