Engine interals have a brown coat of "rust"

[tothewall]

Hello, new to the site.
I have myself a XTM XST Truggy with the .247 and loving it.


On to my question, I'm not even sure what to call, it seems to be a build up of some form of maybe un burnt fuel or fuel contaminated with air and its on the combustion dome, in the crank case, and looks to be in the cylinder a bit aswell.

I run the truck about once a week and i run it hard. I allow it to warm up fully before i dig into it. For fuel my LHS has a couple kinds, I'm running whats called Backyard Basher 20%NM / 16% oil. The engine itself probably has almost a gallon and half gone through it since new, it runs very strong, but I'm jus curious as to what this brown/ rust coloured stuff is I'm seeing.

Thanks, Sean

 

[olds97_lss]

It may just be the coating from the castor oil in your fuel. It creates a brown layer over everything. If it's on the aluminum components and brass sleeve, that's what I'd say it is. It doesn't cause any harm. I usually clean mine out once a year to avoid them getting all enameled up over the winter. I then coat the internals with a light coat of oil before putting them away.

If it's on your crankshaft (steel), then it's actually rust.

 

[shadycuz]

I don't mean to highjack the thread but what kinda of starter plate is that?

See I just got a XTM 24.7 used and it looks to be in great shape, however it doesn't have the correct back plate on it. I'm not sure what I need to get it running but I think I need a backplate with OWB and the pullstarter shaft but I'm not sure.

 

[Scrogg]

www.hobbypeople.net
Search results...you'll find what you need here. Or check out E-Bay.
http://www.hobbypeople.net/guru/HPS_275094160.asp
You can go roto start instead of pullstart. Much more reliable.

 

[tothewall]

It may just be the coating from the castor oil in your fuel. It creates a brown layer over everything. If it's on the aluminum components and brass sleeve, that's what I'd say it is. It doesn't cause any harm. I usually clean mine out once a year to avoid them getting all enameled up over the winter. I then coat the internals with a light coat of oil before putting them away.

If it's on your crankshaft (steel), then it's actually rust.

Alright, thats an answer I dont mind hearing lol. Thanks, I was thinking it couldn't be to serious.
The fuel I'm running claims to have some form of after run oil mixed in with it already, so I'm okay to let this thing sit for periods of time after I run it then?

 

[Karl M]

I'd use after run oil regardless of fuel claims.

 

[Scrogg]

The best thing to do for all nitro engines is to completely burn all the fuel out of the engine. Just running the fuel tank dry is not enough. Refire the engine until it no longer tries to start, set the piston to BDC, then you are done. Sidewinder does leave a protective residue. Any kind of oil is good for the engine once in a while. At least once a month. Also another big factor is to store your rigs in a climate controlled environment. My engines always stay in the house when not in use.
As for the brown coating, clean that crud off. It's not good to let it build up over time.
O'Donnell's fuel is one of the best fuels for keeping the internals clean. The synthetic lube does not gum up like castor oil does. My buddy's F4.6 from his Savage X has 10 true full gallons of O'Donnell's Race 30% on it and still runs good. No bearings or engine parts have been replaced on it. Granted it was one of those very rare "perfect" RTR engines right out of the box. It was flipping the Savage X on it's lid by the 3rd tank of breakin at 1/4 throttle, we where not trying to rag it either. We where doing a proper heat cycle break in.
Denatured alcohol and a cottom buffing wheel on a dremel works great for cleaning internals. Super fine grit rubbing compound with water and cotton buffing wheel is great for the stubborn areas. Rinse everything with D. A. thoroughly afterwards and oil the crap out of the bearings and P & S before reinstalling the parts.
Do this every two gallons and replace the bearings if the develop any slop and your engine will live a long happy life.