That was kinda what I suspected. I would go ahead and burn it out. You'll need to take it on the road to get a good enough pressure and heat to get them clean. It will clean out though and steam like an old locomotive for awhile, but won't do any damage.If you don't want anyone to see your Cobra fogging the place, you could do it at night
. Because of the slower steam rate of water/
antifreeze mix, you might think it will never clean out, it will though and may even take come other carbon build up with it.