Fuel Tank plug/grommet on the side LEAKING

[derelict]

Hi t-700 building/built freaks

i have a problem, that the fuel tank plug/grommet on the left side of the tank is leaking fuel as soon as i pass the plug....WITHOUT the engine (YS 91 SR) running...

The grommet/plug is NOT damaged! Did someone ran into this problem too ?

how can i fix that ?? would a little bit of silicon arround the grommet before putting it in again help ?

Thanks for any help as soon as possible... i couldn't maiden my bird today because of that :(:(:(

Greets

Marcel

[Edvard R]

Hey Marcel - just checking: you did make sure to remove the drip plug from the pipe before fueling up the tank?
If the pipe is plugged, the pressure gets too high in the tank and the fuel leaks through the rubber grommet...

Sorry if this is not the cause, but I have seen this quite a few times... ;)

[derelict]

yes i did that.... but it leaks with or without the pressure line. it should withstand the pressurization anyway... shouldn't it ?

It just begins to leak as soon as i pass that grommet! :arggg::arggg:

marcel

[Edvard R]

Gruezi Marcel,

I just tried on mine with the plug left in the pipe, and no, it doesn't withstand the pressure when the plug is in and it is leaking... plug out, no problem

So, it is leaking even if you remove the top pressure tube going to the pipe? Sounds strange...:dontknow maybe remove the grommet and re-install to make sure it is properly seated and there are no burrs on the edges of the tank.

[derelict]

how come you know that swiss German salutation ? :)

well but that concludes that it will not withstand the pressure when the motor is running ?!

and no... it is leaking even though the pressure tube is not connected.

So any tips i can make that grommet a bit tighter so it's not leaking .... everything seems to be in good shape!?

Marcel

[Edvard R]

how come you know that swiss German salutation ? :)
well but that concludes that it will not withstand the pressure when the motor is running ?!


When the engine is running, the fuel flow to the engine and the muffler pressure creates a cycle, so there is no problem with over pressure when the bird is alive... It is only when you are fueling up that you increase the pressure in the tank from the engine side.

Anyway - sorry I can't help you out, but I am sure there is some good reason for this and that someone on this forum knows the answer...

P.S.: I lived in Switzerland for 5 years...;)

[mk1spitfire]

whats the point of the second unused bung?

[cbdane]

I'd remove the rubber stopper and check the hole carefully for a molding defect or flashing that could be trimmed off. This might be keeping the stopper from sealing correctly.

[derelict]

well... i already did that... there is no visual sign of a flashing or molding defect... neither by feeling or seeing !

i temporarely fixed it with a rubber o ring arround the grommet.... and then sticked it back in... i hope it will stay in the hole !

does anyone have a better idea/fix for this ?

Marcel

[Edvard R]

Marcel - BTW - did you check that the top vent hole was clear and open? I remember I put a drill bit through the vent hole and it did take out a fair piece of left-over plastic...

[4cyclic]

I have also a bit of leaking. I will check for minute flashing , then try silicone.
there is no way I will let it leak, tank pressure or not.

[Finless]

I have not had a single problem with leaking! Crap! That plug fit so tight no way! But if you have even a mild ridge flashing then good chance it will leak! You cant expect a rubber plug to conform to a sharp edge.......

Bob

[derelict]

well... i've trilled that hole out on top of the case... just as per finless video!

ran 5 tanks through it today at it seems to be fine with that rubber o ring arround the grommet.... i can post a picture if anyone is interested!?

Actually it seems like the main fuel outlet grommet of the tank i leaking juuuuuuuuuuuuuust (as finless would say ;-) ) a little bit as well!

@4cyclic.... how would you apply silicone to it ? just a hair of silicone around the grommet ?

Marcel

[4cyclic]

Well, I just ran 6 tanks this am, and after rotating the plug a bit, it does not leak anymore, pressure or not, so I'm done .

John

[MrMel]

Min leaked directly when I tried to start the heli, so pressure from my YS was enough.
Tried turning it but it didnt help, it does turn VERY easy though, so I suppose Oring is the way to go.

[derelict]

the oring worked quite well for me... 3 gallons through it so far.

marcel