Afterun oil in your engine.

[trillian]

It must have been stored in an area with high humidity or something. I have not yet had an engine go off in such a way even when not run for longer than that and so far I have not used after-run oil, but I got some recently.

Funny thing is Tim thats why I'm looking for a spare engine, have'nt used my 600 for 4 or 5 weeks and at the week end decided to have a chuck around with it, when I put it away last time the tank was emptied but no after run oil, I fitted my exhaust plug and left it on the shelf.
Yesterday started it up and it sounds like a bag of nuts and bolts, a rebuild in order. This engine was only about 5 or 6 gallons old, I'm not impressed. Should I have used after run oil? who knows.

[dam74]

My second hand hawk pro has a .32 engine in it that is rusty. Hobbystores said it should of had after-run oil put in it when not in use. So I'll be doing that from now on.

[waveydavey]

One of the boys at the club when he's finished returns to the pits with it running then finishes of the run with another siphon bottle full of 0% nitro as it's the Nitro thats hygroscopic. Lets the engine run for a few seconds and hasn't changed a bearing all year

[GravityKills]

I now take the backplate off after every flying day and put in actually quite a lot of spray oil.
Whether it's effective, I can't tell...

[Downdraft]

It must have been stored in an area with high humidity or something. I have not yet had an engine go off in such a way even when not run for longer than that and so far I have not used after-run oil, but I got some recently.

Strange thing is it was'nt, stored my Raptor titan on the same shelf for 5 months the only thing that was'nt the same was the fuel used. The Titan was always run on Wildcat and the Rex600 that failed has always been run on Optifuel from new. I dunno, your guess is as good as mine.

[oscar9709]

I now take the backplate off after every flying day and put in actually quite a lot of spray oil.
Whether it's effective, I can't tell...

I personally come home and put my helis back on the shelf till the next time,and get alot of stick for not cleaning them ect.But they all seem to fly faultless every weekend (touch wood lol)
How often are you guys changing rear bearings then?

[trillian]

Strange thing is it was'nt, stored my Raptor titan on the same shelf for 5 months the only thing that was'nt the same was the fuel used. The Titan was always run on Wildcat and the Rex600 that failed has always been run on Optifuel from new. I dunno, your guess is as good as mine.

Yeah, I worrry about this stuff. I want the engines to last as long as possible.

[GravityKills]

oh don't get me wrong I didn't say I'd clean it :-)
Ok I wipe over it with a towel so it's not dripping oil. Otherwise I don't really care. Life's too short for that.
But changing the bearing is a drag, and so is flying with a worn bearing, because of the lost power.

[Andy from Sandy]

it's the Nitro thats hygroscopic

Although nitromethane is hygroscopic it is not as bad as the methanol. The burning of nitro creates nitric acid and it is this that is probably doing the most harm. The vapours are probably getting back into the engine. For sure this is what does the fuel tube in the main tank when running muffler pressure.

[Rctintin]

+1 for Automatic Transmission fluid.

When I was racing brittish champs 1/8 off road and 1/8 circuit cars, I would at the end of the day run the tank dry, and then drip 4-5 drips of Automatic Transmission fluid through the carb and spin the engine over on the starter.

Never had to replace a bearing in all the motors I had. (and these engines were reving to 35k rpm! and on 25 or 30% nitro)

On a heli it could be injected into the carb through the fuel line.

[dam74]

Cheers for the tips, probably cheaper by the ltr than after run aswell as with anything that is a luxury hobby they mark up the price

[Rctintin]

Back when I was racing the cars, I was told by someone who knew that the after run oil that people were buying in small bottles was indeed just Automatic Transmission fluid!

Great stuff as it wont go thick and will burn off in the first 20 sec of the engine running.