Any help here would be appreciated
Here's my story: i decided over two months ago to dust off my old hpi nitro mt2 car, as any one woul expect it didn't start and i took it to my local dealer who suggested to buy a new engine, i got a new hpi g3.0; he got it installed and broke it in; it was running great until last weekend, the engine overheats and i am having any kind of behavior; first as it overheat it didn't run foward with the engine on and oil began to burn over the engine; i researched this and read that i mus have been running too lean and must have an air leak, so i got RTV and sealed just below tha heatsink, then oil came out of the exhaust tube (where it attaches to the engine) so i sealed it as well; then less oil came from the lower part of the caburetor, so i sealed it as well (just the base, not the needles) i reset the needles back to factory settings since the first overheat; now my engine is sealed, needles reset, but it still overheats, it starts great while its warm, but as soon as i start reving it up it begins stalling, then turns off and doesnt start when i try to turn it on again, also when its very hot i can hear something boiling inside; what would my next move be? I am using 600F resistant (red) RTV, 16% nitro fuel, my old mt2 chassis/servo and remote

Your Nitro content seems a little low. I would run %20 percent at least if not %25. I have the same motor and it loves the %30 I use. I would get new glow plugs and invest in a temperature gun so you can verify your Temps. Make sure your clutch is OK and not binding anywhere.

Thank you for your reply; you are totally right, its 20% nm and 16% oil; how do i check for the clutch binding? How do i solve this?

Remove the engine and make sure the clutch bell spins free. When in doubt replace your glow plug and set needles back to stock.

I have already check this and it indeed runs freely, i will check with a new plug, thank you very much; i'll post my results

You're still too lean I believe. Sealing all of those parts of the engine was a waste of time. These engines are not perfectly sealed and do leak a little sometimes. Oil or fuel pouring out is bad - but a little wetness here and there is not out of the realm of normal. The boiling noise you heard is fuel boiling in the crankcase. If you have the needles out of whack, one can be too lean and the other too rich. Start over. Back both needles out richer. If the engine runs as it sits now, fire it up and richen the needles (both) so it takes off sluggish and doesn't rev very high. Now lean your high speed needle until it revs out nice and your trail of smoke is still blue. Once it's running out nice, lean your idle mixture so it revs quickly but snaps back to idle quickly after you let go of the trigger. When your idle is set properly, it will drop to idle very quickly and after about 5-7 seconds you should hear the rpm drop slightly. What you want in a properly tuned idle mixture is to have it drop idle within 10 seconds, and slightly load up a little. If it sits for 30 seconds idling without blipping the throttle, it will probably flame out. If it's still overheating (over 300F and smoking), check the driveline in the truck to make sure there are no worn bearings or bushings. It may involve taking a lot of stuff apart.

Posting pictures of these things that were at fault can sometimes help determine what the problem is (example - the oil and fuel leaks that were later sealed).

Ok, here's my update so far: i changed the spark, rebuilt the engine and sealed leak proof, but still overheats, i leaned out both needles farther than the factory defaults, by 1 turn; set the idle screw for 1 mm gap; there are two things that mainly concern me now: the car goes forward without pulling the trigger with this idle setting, and if i rev down it turns off; and the other thing is that the muffler still spits oil and sometimes gas, is that normal? as i learned it should do that only during the break in process

Overheating is almost always due to too lean of a setting. Curious what you consider overheating? How are you measuring engine temperature? 1mm idle gap is most likely too big and possibly why your car is moving at "idle". Ensure the throttle is not closing further when you hit the brakes. If it is, you need to adjust your linkage or throttle trim so it closes to be idle stop when the throttle is neutral. If the linkage is set correctly and the throttle isn't closing further with the brakes, then check your clutch springs. A broken clutch spring will allow the clutch to grab even at idle.

With the exception of gasoline engines, all glow plug engines will spit oil from the exhaust. You will see more oil come from the exhaust using high oil fuel - I think 16% oil for regular running is too much. I wouldn't use more than 12% oil fuel. 20% nitro is fine though.

I would richen the high speed needle and maybe even the low speed needle to lower the idle. Again. 1/8 of a turn then let it run for 20-30 seconds to see how it reacts before moving needles again.

Remember only small needle moves.

Do NOT use the idle mixture needle to lower the idle. I would start all over with the needle settings. Whatever the base needle settings are in the manual, go 1/2 turn richer than that. Set the idle gap for .5-.6mm and tune the engine from there. Always set your main needle first for a nice clean and smooth run up to WOT. It should sound clean. Next set the idle needle so it will transition from idle to high throttle smoothly but still drop immediately to idle after letting go of the trigger. After it drops to idle, listen to the engine idling. After 3-5 seconds the idle should drop slightly and stay there. It should slightly load up if left idling for 15-20 seconds. At 30 seconds it will probably flame out if you burp the throttle too quickly. All of your performance tuning should be after the engine is thoroughly warmed up - usually 1-2 tanks operating above 200F is usually adequate.

quick and probably dumb question: i am using traxxas 3232x glow plug as it came as a replacement for my hpi g3.0 engine, would this be my problem? should i use a cold or medium-cold glow plug? my engines is not leaking anymore, as i resealed it, and i've been struggling with tuning, but i have not run the car more than 5 min because i don't want it to get hotter (today i will get the temp gun), i'll let you know of my progress

Traxxas plugs work fine, but I've found them to not last as long. I prefer McCoy plugs for long reach applications like yours. I usually use MC59 hot plugs, the MC8 is a medium and MC9 is cold. I would stick with a medium or hot plug and run your needles richer. You're clearly too lean or have a mechanical binding or both. I'm breaking in a Picco .28 right now that I have to work pretty hard to get it to heat up to 265F. If you're topping 280F in 5 minutes or less, you're way too lean.

Well, as promised, this is my update, i went today to my dealer here in Panama, he found out that my servo was closing the carburetor completely when braking; he moved the throttle one tooth in the servo and now i tuned with all your instructions, i seem to be running 211F, everything seems cool; i really don't know how to avoid this problem, but i hope this post help anyone

Pretty common problem. We'll at least you learned one of the basic things about Nitro. Check your servos and linkages.

By the description, they adjusted the servo horn to just not close the throttle all the way. I hope that the idle stop is set so when the brakes are engaged the throttle doesn't still close completely.

To add - this still doesn't explain the perceived overheating. Still curious how this overheating condition was determined..?