lopflyers

My Feedback: (12)

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

Hobbsy

My Feedback: (102)

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.

lopflyers

My Feedback: (12)

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

SeamusG

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 ...

earlwb

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.

lopflyers

My Feedback: (12)

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.

AMB

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

lopflyers

My Feedback: (12)

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

1QwkSport2.5r

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.

Sport_Pilot

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.

lopflyers

My Feedback: (12)

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

fizzwater2

My Feedback: (61)

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

lopflyers

My Feedback: (12)

32 ounces, it used to last 12-15 mins.

fizzwater2

My Feedback: (61)

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.

1QwkSport2.5r

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.

Sport_Pilot

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.

lopflyers

My Feedback: (12)

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.

lopflyers

My Feedback: (12)

lopflyers

My Feedback: (12)

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

lopflyers

My Feedback: (12)

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

lopflyers

My Feedback: (12)

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

jeffie8696

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

greenjeep

My Feedback: (3)

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.

lopflyers

My Feedback: (12)

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