If you have a hole in the engine, then you need to address that. Either by replacing whatever broke if parts are available or buy a new engine.
But before I went to that expense, Id make sure to narrow down the problem. No reason to spend money on a replacement engine, if its just a cracked fuel line. That's a couple bucks vs. a couple hundred. If its an actual engine problem that severe, it probably shouldn't start in the first place and even if it did, it will run like crap.
But start at square 1. And BTW, these are just suggestions from some stranger on the interwebz...so if you break it or cause harm to yourself or your RC, don't yell at me, I don't want to hear about it
:
Clean it up.
Go over the fuel lines, every mm of it.
Check each fitting for cracks or broken.
Make sure the exhaust fittings are tight and that the rubber coupler is sound. Any crack here will leak. Also make sure that it is in the proper position and that its not just barely catching hold of either the manifold or pipe. And BTW, manifold can develop hairline cracks to that are hard to see until it eventually breaks completely off.
Check the entire fuel tank. Remove it if you have to, so you can inspect the mounts. These can get cracked. Make sure the fuel door is closing and sealing properly. Most have some form of adjustment to tighten if needed. Make sure all O-rings are okay and not showing damage.
If all look okay, then before I removed the engine, Id fill the tank and prime it so that the fuel lines are full of fuel. Let it just sit with paper towel or shop rag under it and keep an eye on it to see if there is any wet spots forming.
After an hour or so, Id fire it up. Is it running okay? Just let it sit at idle and watch it for leaks. Only this time make sure not to have paper towel or rags near the exhaust or engine, so they don't ignite by accident. What are the engine temps just sitting? Do you have a infrared temp gauge? If not you need one ASAP. If its running rich it will be running cold. This will cause excess fuel into the exhaust. without a temp gauge, your only guessing at this point, and most likely guessing wrong. But if it is running proper and still no leaks, then go run it in the yard for a while and keep checking it. If still nothing, then Id shut it off and let it cool down. Normally you should be removing any left over fuel out of the tank when your done running it, but for now let it sit and see if any leaks start while it cools. Keep checking for up to an hour. If nothing then drain the tank and lines.
Remove the engine and inspect all bearings, gaskets. Make sure the head is tight, but dont over tighten and strip the screws. Your most likely going to need to be able to remove the flywheel and starter assembly to inspect the bearings. Is this something you r able to do?
again, lots of 'maybe this' or 'could be that' going on. Could be its just one of the pitfalls of owning a nitro RC. They can be messy. I had 2 of the original TMaxx's when they first came out back @2000/01-ish and they both leaked like a sieve all over the chassis. In both cases it was just left over exhaust blowing out the muffler.
If you get to the point where you can't figure it out, or tearing into it is beyond your skills or comfort level, then before throwing any money at it for expensive engine, Id hand it to someone who knows nitro rigs really well. Either it be someone at your LHS if you have one close by or maybe a friend that can help you out.
