I have a TT 120 that is loosing fuel. Whe I looked closely is leaking through the head.
I tighten those screws very hard and is still leaking.
Its a brand new engine with probably 15 flights on it.
Is there a gasket in there? Is it possible for the gasket to be bad this early?
Can I put high temp thread lock or sealant on it?
HELPPPPPPP

Did you take all the screws completely loose to make sure the head was sitting squarely on top of the cylinder. Too tight is as bad if not worse than not tight enough.

I did......NOT. I will do that tomorrow [X(]

When you re-torque the head screws tighten them in stages and criss-cross the head while tightening. If it has 6 screws - tighten 1 & 4, then 2 & 5, then 3 & 6. Start with enough torque to seat the head on the cylinder - do all 6. Then start over and tighten to snug. Then start over and tighten to tight. If you use brute force - you will need to get the head repaired.

HTH

RCUtechs must be on a dinner break and have taken the picture server with them for company ...

Carefully wipe off any oil residue on the cylinder top, head gaskets or shims and head itself. You don't want a oil film on them when you reassemble it. The oil film can keep the parts far enough apart to not make a good seal.

Hey thx for all the advise. I'll let you know if this helps. It ran lean for a couple of times due to dirt in the carburetor. That might have loosen the head.

If got really hot from a lean run could warp the head, not likely but could happen martin

Oh no, it's a new engine. Don't tell me that I need a new head

Are you seeing any bubbles coming from under the head or is it just wet? All of my 2-strokes spit a little fuel when running that accumulates on the front of the engine. It may appear to be leaking fuel out from under the head but it shouldn't be unless the mating surfaces are that poorly machined. I don't see that happening with a Thunder Tiger though. They are made well IMO.

Just my thoughts.

That is correct, you will see bubbles coming out of the head while running if it is leaking. All engines have fuel stand off at high RPM which spits fuel out of the carb.

Oh no, it is not bubbles. I can see a drop dripping at low RPM, and a full tank will last me 7-8 mins

How big is the tank, and does it still run like it should?

32 ounces, it used to last 12-15 mins.<div>It all started w the engine going lean mid air. When I took the carburetor apart it had dirt on it.</div><div>The bison muffler was loose too. I cleaned the carburetor, tighten the muffler and the head, adjusted the high end needle and now it is running well but it is leaking a lot.[&amp;:]</div>

I would think if it's leaking at the head, it wouldn't run very well.

If it's leaking out the front bearing, which ends up getting fuel everywhere, then it may still run ok but use a lot of fuel.

Kinda tough to diagnose a problem like this without seeing it, could be all kinds of reasons.

Is the backplate secure? o-ring under the carb intact and in good shape? Like someone else mentioned, don't overtighten things, you can ruin a head doing that.

I agree if the head was leaking it wouldn't run well. Its a fact that almost all model engines spit a little fuel while running, more noticeable at higher rpm. I'm willing to bet thats the problem. Otherwise there would be bubbles showing up around the head while running.

Obviously there are no pictures or videos posted, so this is an assumption but I've noted it on all of the engines I own. The sloppiest engine for spitting back is my Fox .40 that has killed itself. The next worst spitter is my Enya 60-4C but this one is more of a dripper than a spitter.

To the OP: If you still think the head is leaking, get a video of the engine running, being throttled up and down. This will prove one way or another whats going on.

He is seeing fuel collected in the gap between the head and engine that will drip down when at idle.  If it was leaking it probably wouldn't even idle.  Fizzwater has it right.  If not leaking from the front bearing, then the fuel tank, fuel line, or carb is leaking fuel.

Hey, that is very helpful. The tank was leaking a few weeks back. The interior bay was moist. I took off the tank and the screw in the center cork was loose and leaking. I fixed that and cleaned the interior really well. Now is not wet.<div>The carb came out last week when the plane was getting lean midair. Maybe that is where the leak is. </div><div>Very windy today in Central Fl so I think I ll work on this today and let you guys know</div>

<div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-color: rgb(255, 255, 255); font-family: Arial; font-size: 12px; -webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); "> I opened the head, cleaned with alcohol, put it back together flat using the 12-6, 2-8, 3-9, 5-10 technique.<div>I checked the carb and backplate. I also checked the carb. Nothing leaking now bur sputtering at high rpm.</div><div>The previous leaking at idle is no longer there. I'm trying to post a video, but you guys know how hard it is.</div><div>If the winds let me I ll fly her day after tomorrow.[img][/img]</div></div>

[img]webkit-fake-url://C63E0522-1168-42BD-9E61-5DCC1D7B9E34/imagepng[/img]Oops, yet another failed try. Will come right back

http://i1071.photobucket.com/albums/...9/3cb86f4b.mp4

Fixed, the gasket was all bended from the to tightness [X(]. Now is not leaking

That was a very leaky head gasket LOL . Glad you got it figured out.

Ihave a Magnum engine that was doing the same thing. Pulled the head and it did not have a gasket. Added a gasket and no change. Messed with it for a while and got to wondering if it was possible that the leak was coming from between the crank case and sleeve. A very small amout if silicone on the outside of the sleeve solved the problem. Just to make sure it was not a fluke I removed the silicone and the leak returned. Reapplied silicome and no more leak. Believe it or not.

Go figure, I never imagined I bended that gasket in a new engine without a crash or anything.