Ok...
The engine is a GMS .47 with maybe 1 gallon of 10% omega run through it. I bought it from Mecoa's auction on ebay for less than 50 bucks NIB, and it is one of the best running engines I have ever seen. Straight out of the box, I carefully ran three tanks of fuel through it before it ever got airborn. I know its not fully broken in yet, but here is the issue at hand.
I mounted it to my trainer, swinging a 10x7 prop and had a handful of flights on it when one day I lost radio contact with the plane right after putting it in a nose dive and applying full throttle...the plane was turned into firewood and I had to dig the engine out of the soft dirt. Thankfully I was flying over a freshly plowed field. I blew the dirt off with an air compressor, dismantled it, and hosed it down with WD-40(bearings, crankshaft, etc...) I blew the gunk out again with the air compressor and repeated the process two more times before putting it back together.
Now I have this engine mounted on a Super Sportster swinging an 11x6 prop. The engine still runs great and will idle real low for a long time and not even hiccup when going to full throttle. Given the price I paid and how good this engine runs, I am very partial to it.
The problem is that the exhaust oil is very dark...well its black. Today while flying, my throttle arm loosened up on the engine so I had no control of the engine speed(yep! you guessed it- full throttle again) so I had little choice but to fly the plane at WOT until it ran a full tank out of fuel. When I deadstick landed it, I realized how dark the exhaust oil is (it shows up good on white monkote)
My question is this- is this normal or has the engine sustained more damage than I thought. Is it a mixture issue or what? Any advice on this is greatly appreciated as I am not very experienced with glow engines

Black like this is most often aluminum rubbing against aluminum somewhere.

As w8ye said, that can be the result of metal-to-metal contact. Sometimes, the contact is a serious internal condition, but sometimes it is just the parts of the muffler being loose. I would make sure that the muffler is tight before I worried about the internal parts.

Sandy T

Are you using an after run oil, especailly if there is a ATF componenet in the mix? If so, sometimes it burns black (or at least dark).

Cheers,

Chip

Guess the first question I have is what color was the exhaust oil before the crash? My experience with engines is that an almost new color of castor oil comes out of the mufflers when
fully broken in. My Magnum .40 continued to spray out black exhaust on 20% castor oil fuel for
a long time after the break in run was done. After landing flights later on, I found almost a clear
color of oil splattered on the trainer. Some engines take longer to wear in. Now the Evolution
.46 engine just recently acquired in a model purchase, only took the Dave Gierke ABC break in
run to have the oil color change to clear yellow. When you finished your cleaning after the crash, was there any wear noted on the back plate, or a lot of crankshaft end play? As has been
suggested on this thread, there could be something creating metal flakes. I would certainly
inspect the engine parts again before continuing to fly it. I am not familiar with Omega fuel oil
content, but hope there is some castor oil in it for protection from a lean run.

I lost my first .47 in a flyaway, and purchased three more to feel better. I am sure this thread
will answer your question.

More than likely the crankshft was pushed back a bit when you stuck it straight into the ground. That allows the crankshaft or con rod to touch the back plate causing the black crud. Remove the backplate and using a punch of some kind, stick it into the fuel passage and tap with a hammer. This should drive the crank back forward.

Thanks everyone for the advice.
Aerorich to answer your questions, Omega fuel is pink and the exhaust residue before the crash was light pink. I am not sure of the oil content of Omega, but I'm thinking its 18%. I have heard that the GMS/Tower hobbies engines take a good long time to fully break in.
I believe, however that SandyT hit the nail on the head- at least I hope. When I mounted the engine on the Sportster, I loosened the muffler bolt to turn the exhaust outlet to the side, and I thought I tightened it up real snug. I pulled the engine out and tore it down last night, and I did not see any wear (shiny spots) anywhere inside. I decide to take the muffler apart as well, as I did nothing to it after the crash. I believe I found that there was still a lot of dirt around the lip of the cast part of the muffler wearing on the thin body of the muffler. I think I aggravated the situation when I loosened the muffler screw and then re-tightened it without cleaning it. I found that the muffler screw was in fact snug so I'm hoping that I found the culprit, but still not sure. I cleaned all of the pieces before putting it back together, and will run the engine tomorrow to see if that was the cause of the problem.