Well guys, it seems that you were probably right about the tank. I got my new engine today. I did get it to run perfect! Then it started acting funny. I noticed a significant amount of bubbles in the line this time. So I figured, heck, if I fill it back up all the way it can't get air. And it did run fine when I filled the tank. Then I shut it off and noticed fuel coming out of the back of the tank compartment.

I think I definetely have a tank problem. Thats gonna suck because I glued the servo try in. Its going to be a royal pain, but at least I know I HAVE to now. And my plane lookes a little better with an engine without JB weld all over it.

I will let you know what I find.

Thanks guys,

Wings

Unfortunately... lite ply and fuel soaking is a MAJOR problem. better get some corn meal in there to start absorbing fuel (NOT CORN STARCH! thats a heck of a mess.)

I never win.

I managed to get the tank out and I found the problem. It was fairly obvious. The fuel line was ripped almost all the way around where it hooks on to the tank. I took the line out of the tank to to make sure everyting was ok there since I had it apart. I had to remove the engine and replace it.

After all that now it runs almost alright, its probably flyable, but somethign is still wrong. I still see air in the fuel line!

And it revs up niceley and screams, but it kind oscilates slightly. Like I say, I think it is flyable, and it is not lean, but its not right.

I am mad[:@].

Looks like I will have to take it apart again.

The only think I can think of is on my trainer I had a problem with the clunk getting stuck forward.

I took the advice of Minnflyer and split the line and put tubing in the middle to keep it from coming forward. I think maybe it is getting air there.

I stuffed the entire tank area with all kinds of foam. I don't think it is moving.

Anyone have any suggestions?

I really don't want to take it apart again.

My receiver was soaked with fuel also. I took it apart and fortunately all the electonics was dry, so I think its ok.


As far as the balsa soaked, I guess what is done is done, not much I an do about it now. I don't even know what your taking about putting meal in there. I tried to wipe it best I could. I am not making a run to any store to buy obsorbent I have to work tommorow.

As much foam as I jammed in there, its bound to get soaked up.

it's the oil that is the problem. oil soaked wood is not strong and bends easily. you will probably have to repair that. i would replace all the fuel lines. however, you say you see bubbles in your fuel line. let a piece of line stick that goes to the needle so you can see it. if the fuel has bubbles coming in, it is behind the needle valve. if you see no bubbles coming in but there are bubbles coming out, guess what! you suffer from leaky needle valve syndrome. however if you do see bubbles coming into the needle and you have replaced all the fuel lines, (including the clunk line) than you have a leaky tank. process of elimination guys.

I just had it apart, there was no visible holes in the clunk line. I guess there could have been a pin hole leak. I didn't look that closely because I assumed I had aleady found the problem.

i suggest you cut a hatch because you may have to take the tank out several more times to fix the problem. simply relpace all the lllines. you will never be able to find a pinhole leak unless you do a pressure test. jsut replace them all. but could you tell me whether you see bubbles coming into the needle or not?

jettstarblue,
Good damn job buddy!
That is a first "Don't throw it out, send it to me and I will fix it and send it back" buddy, you are going straight to heaven!!!!
Where were you when i didn't even know the difference between the vertical stab and low speed needle?
If I could vote for RC Universe "good samaritan" award you would get it!!!
Good job buddy.
Lean540

Corn meal is highly absorbant... soaks spilled fuel up really quick. It can soak the spilled fuel OUT of the wood!

You CAN remove the mojority of the fuel that soaked in... and the sooner you start trying the better the result.

Apply corn meal (the stuff used to make cornbread)... then let it sit overnight. Clean it up.

Brush on denatured or rubbing alcohol. (not a lot... ) reapply corn meal. Overnight again. Clean it up.

More corn meal... heat it with the heat gun from the outside. clean it up.

That Should remove over 80% of the fuel that soaked into the wood. (if you started soon enough...)

The longer the fuel was allowed to soak in before removal began... the deeper it got. and the stuff that got deep is there forever.

FH, good way to clean the fuel up. I've used course ground wheat flour before, though the corn meal would more than likely work better.

Lean 540; Good to be acknowledged! Thanks a million! I just try to help when I can......and sooooo.-

Wings-You may have a problem where the tube comes out of the tank ie. it's sharp, and cutting your tubing. When you take it apart, use some sandpaper to smooth the end of the tube 220 grit should be fine. Also to check for "pin holes" use a moderate amount of pull and stretch the fuel tubing, this will show any holes. Don't give up, and if you get mad, just take a break-no Mexican Hat Dancing on the plane!!! Fix it right, and you'll be glad you did. You've taken it apart several times, so it's just a little easier now. (last summer I took apart the transmission on a rare motorcycle I own 40 times before I got it to work!!!!! No kidding!) So keep at it, and you WILL get it. I also have a kitchen garbage bag full of old tanks ect. if you need one, let me know, and I'll ship you a ready to go tank, just let me know the size.
Sometimes it tough when you don't have a hobby shop who will help, or not much money, or whatever, just stick with it, and I promise, you WILL enjoy this hobby!

Jetts

Well,

I took every thing apart. I did away with the fuel tubing in the center of the clunk line as mentioned above. I put a differernt clunk on there (the one from my old plane). I put new fuel line and then I tried it.

Rather that putting everything back all perfect I figured I'd take the smart approach. I left the foam padding out, left the receiver hanging. I singled nutted the engine mounting bolts because it takes me forever to double nut them. Basically just did what was necessary to try it just in case it didn't work it wouldn't be so much wasted work.

Well, it worked perfect! No air in the line, ran great. So, I spend an hour and a half buttoning everything up, adding foam, the whole 9 yards.

Then I tired it again. It still runs great, but at full throttle there is still air bubbles (before the needle valve) [:@]

But like I said, it runs good. A tad bit unsteady at full throttle. But I think I am going to go with it.

I have a great planes tank. The exhuast line is just a port straight into the tank. It doesn't have a place where you can install a fuel tube bent upward. I wonder if that could be the source of air?

There is really no since in taking it back apart because I just replaced everything besides the tank. My major problem was the split fuel line and that is fixed.

Is it out of the ordinary to see any kind of bubbles in the fuel line?

Thanks for your help guys,

Wings

I don't know if it's normal or not but I have bubbles pretty often in my fuel line and I haven't had any problems.

well, some bubbles may be expected, especially if it is low on fuel. there are bubbles before the line and you have replaced everything so it is probably vibration. a quick question. did you mount the tank cap to the firewall with silicone glue like they tell you to? that will cause your tank to foam and would explain most of your problems.

O.K., one last thing now that you have the tank squared away-I'm not kidding here either, I do it to ALL my fuel before it ever get to a plane- Ad 2-3 drops of Armor-all (the stuff that makes the dashboard of your car all shiny and slippery) to your gallon of fuel. This will DEFINATELY stop any foaming caused by vibration. It won't hurt, or affect anything else-before they sold it with the lable armor-all, it was actually an industrial de-foaming agent. Here's a test if you don't believe me, shake your fuel jug vigorously then when you stop, it's nearly all foam for a few seconds, quickly remove the cap and dose it with 3 drops-instant de-foaming! Now put the cap back on, and shake the jug-no foam!
Caution: DO NOT USE ANY OTHER "VINYL PROTECTANT" AS I CAN'T GUARENTEE YOUR RESULTS-ONLY Armor-all.

Jetts
P.S. Wings, you may want to richen that NV just a little more (couple of clicks).

The armor-all trick really works, but it does have 1 side effect. Armor-all contains silicon, which will melt itself on to your glowplug. Over time, this can result in plugs that don't work right. They will slow with the ignitor on them, but the element is covered, preventing the fuel from coming in to contact with it. The more Armor-all, the faster the problem occurs. Just a couple of drops in a gallon should be all you need, and with any luck you'll blow the plug for other reasons well before this buildup is a problem. But if the engine starts running funky after you've put a lot of treated fuel through it, try the plug.

So, its safe to say that some air is ok?


Spaceclam, I am not sure what you are talking about, but no, my tank is not glued or mounted to anything, just jammed with as much foam as I could squeeze in there.



Thanks guys,

Wings

well, a lot of arfs tell you to clue the cap of the tank to the firewall with silicone glue and isolate the rear. i had a similar problem a long time ago with my tank foaming for that reason. don't pack as much foam as you can in there. if you are actually jamming hte foam in there it does no good. make sure that stuff is not sliding around but don't shove foam in there if it requires serious effort to do so

Its not the same kind of foam that I put in there the first time, the kind you buy at the LHS. It is more like an egg crate type of foam. I found it at work. The tank is snug, but not in there as tight as a rock.

So, some bubbles are normal?

they shouldn't be. i am not sure how the egg-crate foam works for this type of application. the egg crate foam i think is a bit stiffer. did you have engine problems before you put in that type of foam?

Dude,

I don't want to be rude, but all I want to know is if some bubbles are normal. I am somewhat new to these planes and that is why I am asking advice. I have a degree in mechanical engineering and have a very thorough understanding of basic fluid dynamics.

The foam is fine. It doesn't need a thorough investigation as to whether my foam is better than other foam. This has nothing to do with it. As I said the tank is in there tight.

I am sorry, I don't mean to be a jackars. I've had a long day and it gets under my skin when I feel that someone acts like they have all the answers.

All I ask is if some bubbles are normal.

Thanks,

Wings

some bubbles can be expected in certain situations while others may not. i can't answer you there. all i know is that i have not had bubbles sence i got rid of my la and all my planes have flown fine. however, it may be acceptable. if your engine runs fine, than they are probably acceptable. it is a common mistake to overpack tank compartments with foam, so i wanted to throw the fact out there because i do not know you or anything about you, so you may or may not have known.. i appologise if you already knew that. i do not intent to act like i have all the answers. i appologise if i come off as a know it all. i am merely providing suggestions, ideas, and answers because that is exactly what you asked for. becuase i do not know your plane, engine and stup i can not really answer your question. it is in your best judgement to decide whether the bubbles you see are acceptable or excessive. i do not argue your knowladge of fluids. i do not know you personally, so i can't argue. however, under the right conditions, glow fuel may foam. but, the foam is on the top, so my thinking is that if the clunk is sitting in fluid, it should be sucking up only fluid unless there is a place past the clunk where air is getting in. see what i mean?

Wings,
Montague is right about the possible glowplug problems, but quite frankly, I haven't had any.
Yes, sometimes a few bubbles are O.K., as long as the engine runs steady, just go with the richest setting you can and still maintain a good 2 cycle, as opposed to a rough or 4 cycle sound (generaly it won't have enough power to take off if it's 4 cycling).
I've used many different foams, and while I've read that some are better than others, they all work O.K. We shot a video, with exploding planes, ect. and in those "disposable planes" we isolated the tank with wadded up news paper, and IT worked fine.

Jetts

Thanks guys,

Spaceclam,

I didn't have a very good day yesterday. I shouldn't have taken my frustrations out on you. I apololgize.



Wings

no problem. we all have bad days. i certainly have mine