Hey GUys,

Just a little introduction:

Went to the field today and spent four hours trying to come up with a reason not to pull my hair out due to engine failures. I only got one flight in the morning and while my plane was vertical during a loop, the engine shut off. I landed it and we took a deeper look. WE started the engine and we held the plane vertical, the engine shut off! WE took out the fuel tank TWICE to see if anything was causing this, we found a slit in the fuel line, but that wasn't it. It's the engine. IM taking the engine apart and i would like any information or tips on what to look out for in an engine failure like this.

Summary:
http://www2.towerhobbies.com/cgi-bin...?&I=LXJA86&P=0
When my engine is in a vertical position, it shuts off. Why does it do this? Its not because of the pressure failure in the fuel tank, there was a slit in the fuel line, but its fixed and still, the engine shuts off in vertical position. I think its a leak or a loose screw, and I'm taking it apart, help me. What do you guys think?

Thanks alot,

Samolot

Generally, if your engine is quitting in flight....it's because it's leaning out
and overheating. Lets assume the fuel system is OK. You might have a
slight air leak....the carb must be tight down onto the o-ring or it will
leak air, and give tuning problems.

If you are not using a fuel with plenty of castor, your engine will run hot.
That's just a fact. If your engine is over-propped, it will over heat. If the
engine is mounted upright, it can overheat in a climb from leaning out.
Using the wrong glow plug can have an adverse effect on the engine. If
the engine is cowled, it may not be receiving enough cooling.

I wouldn't take the engine apart unless it has suffered compression loss.

FBD.

No, the think is, it shuts off when the plane is in a verticle position, meaning the nose is pointing towards the sky.

Is the clunk of your fuel tank stuck in the front of the tank?

Before you take the engine apart, before you play with the fuel tank, before you do anything else...

Richen the mixture. The most common cause of an engine dying when the plane is vertical is a too-lean high speed setting.

Dr.1

There are so many possibilities. One generalization we can make is that the engine is dying when vertical because it leans out in that position. Flyboy Dave mentioned low compression. I agree with him, there's no reason to take the entire engine apart, unless you have low compression, which might give the engine marginal fuel draw, causing it to die when vertical. Usually, a low compression condition will make the engine hard to start and not idle very well, if at all.
A more likely cause would be the needle valve adjusted too lean or an air leak of some kind. The needle valve should not be adjusted for maximum rpm. It should be a little richer than maximum rpm, perhaps 300-400 rpm less than max. would be a good starting point. Others might disagree with that number, but everyone will agree that it has to be somewhat richer than max. rpm.
An air leak could also cause marginal fuel draw, which would be worsened in the vertical position since the fuel would have more vertical distance to travel. Air leaks usually occur in the following:
1) Needle valve threads loose in the housing (can sometimes be cured with a short piece of fuel tubing around the needle valve to make a seal where threads and housing meet)
2) Carburetor to engine joint (try a new 0-ring, and pushing down on the carb. while tightening the draw bar)
3) Engine backplate leaking (try a new gasket or 0-ring, and tightening the screws)
4) Leaking seal on the front engine bearing (requires disassembly and replacement of bearing/seal)
One more thing to check. You said you removed the fuel tank, but you did not say if you DISASSEMBLED the fuel tank. I suggest you check to make sure that the pick up line and the pressure line are not reversed, that both lines inside the tank have no holes/slits, that the pick up line did not get jammed/bent forward and stuck that way from a hard landing or sudden stop, and that the pick up line did not get disconnected inside the tank.
I know some of this is very basic, so forgive me if you already know it. I just don't know how much you know, so I'm trying to cover all the bases.
Good luck, and please keep us posted so we can all learn what worked and what didn't for future reference.

See here is the funny part. I went to the club to fly and spent the day looking at the engine. THe tuning of the engine was the first thing we looked at. THE funny thing is that we had to change the setting to two completely different areas for vertical and horizontal flight. We got it to work with vertical positioning but once we put it on the group, it was running WAAY to rich, which caused no throttle control and eventually killing of the engine. WE took the fuel tank out twice and disassembled it to search for leaks. I found a small cut in the pressure line, which i immediately removed. THE !QUOT!clunk!QUOT! was a bit too low on the bottom of the fuel tank so we shortened the fuel line a bit. This only solved one problem in total. No more air bubbles coming in with my fuel, which anyway is a good plus because the engine was running smooth at idle and all. But at vertical, its the same crap. I got some advice form another member of the club who had the same problem with the engine. It was the same one. What he did though is after an emergency landing due to an engine failure during a loop, is he tore off the engine and pitched it out. HE told me to get an OS .46 AX. Runs great supposedly. No I'm just a 16 year old paying off the hobby by working for my dad, so a new engine is, right now, out of the question. I think i could get this to work. I took the engine apart. What i did is take off the muffler, take apart the muffler, remove the back plate, remove the glow plug, remove the whole thing on the top of the engine which is connected with 8 screws (Im sorry, I'm fairly new to this hobby, and didn't get a chance to learn about engine vocab), and after realizing i cant do much myself. Mostly due to the fact that i live in an apartment building. I cant start the engine here. I can only work on it at the club. This will suck. I really need some ideas form you guys. Oh yeah, i checked the carburetor for leeks, and its not that. There are no leaks in the carb. Its something with the engine itself. I had it on my trainer, and it worked flawlessly, i had it on my step up, the easy sport, and it worked great for the first day,yesterday, it sucked.

Please help,

Samolot

You may not be getting enough pressure to the tank. Please make sure that the nipple on the tank is clear. Also make sure the line from the muffler to the tank is clear, with no kinks or restrictions of any kind. Do the same with the tubing in the tank. You may also need to see how long your fuel lines are. Shorter is better. If the tank's too far aft, there's a problem.

What size tank? Shape? Larger than 10 oz. is too much, and can cause fuel draw problems. Some shapes just pick up vibration better is some models. Make sure the tank is well-insulated against vibration...in some flight regimes, vibration can change enough to excite the fuel in the tank to pick up air.

Do you have one of those rubber exhaust deflectors on the end of the muffler? If you do, remove it and recheck the nose high test. I had a Fox 50 that when pointed upwards, would always die. It wasn't too lean either. I removed the rubber extension and the problem was solved. My guess, is that the rubber xtension decreased the muffler pressure and therefore the push of fuel to the carb.

Also - the Tower 46 is a powerful engine, albeit many people have trouble tuning theirs. Mine took a whole summer of running rich before it really loosened up and started acting like it should - it seems that it takes a lot more break-in than my other ABC engines have.

I also had an airleak around the base of the carb , and possibly at the backplate. I RTV'ed everything I could, and locktited the threads when I put it back together.

JZINCKGRA,

YOUR THE MAN. I havent tried it yet, but yeah, duh. It worked fine all the time, until two days ago i biught the rubber extension for the muffler. Ill try to take it off. It makes sense though becuase it requries more pressure with the extension. It shuold be fine now. Im such a dumbass, why didnt i think of that.

Thanks alot guys,

Samolot

Glad to hear that was the problem. I don't usually have the right answer, but it's nice making the right suggestion every once in awhile.

Usually, a rubber extension will increase the backpressure a bit. With some engine/muffler combinations, that little bit of added backpressure is enough to make the engine overheat and quit. That my have been your difficulty...especially since it happened when the engine was nose-up...a condition that automatically causes reduced fuel pressure to the engine. Added backpressure, slight leaning, and the engine can overheat quickly. The slight additional backpressure would add to fuel pressure, but not enough to cause the engine to richen enough to prevent the quitting from lean. Nose down, the fuel would tend to "rush" to the engine, so you're getting a richening effect.

Glad to see you found your difficulty!

NOW that its working, ill be flying my step up doouble time. THanks alot guys. Hope it works, i think it will. By the way, what planes is this engine good for? I need a low wing flyer, preferably .46 sized, obviously. Im not into the sig 4*, i want soemthing acrobatci so that i can have fun with. Im a decent piolot, never crashed, and i know what i can do and cant do. I get my pleasure in flying, not screwing around.

Here'a a Killer plane, at a killer price....the Kaos 40....[sm=thumbup.gif]

http://www2.towerhobbies.com/cgi-bin...&I=LXZT80&P=ML

FBD.

Preferably taildragger. I have two trike gear planes and no tail draggers.

This engine sucks. I went to the field today thinking it was gonna fly. I took off the stupid rubber extension, tightened the screws, and checked the fuel line. Guess what, same sh*t. My field buddy told me that the engine just had its time and the tower hobbies engines suck anyway. The carburetor might have had its time .Its only 1 year old, and i couldn't believe how it could have been wasted so fast, these engines last up to 30 years, i heard. What do you guys recommend i do? I thought i can send an email to towerhobbies.com, since its their engine and have me send a new one, or possibly fix it themselves. I dunno, help me.

samolot

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Generally, if your engine is quitting in flight....it's because it's leaning out
and overheating. Lets assume the fuel system is OK. You might have a
slight air leak....the carb must be tight down onto the o-ring or it will
leak air, and give tuning problems.

If you are not using a fuel with plenty of castor, your engine will run hot.
That's just a fact. If your engine is over-propped, it will over heat. If the
engine is mounted upright, it can overheat in a climb from leaning out.
Using the wrong glow plug can have an adverse effect on the engine. If
the engine is cowled, it may not be receiving enough cooling.

I wouldn't take the engine apart unless it has suffered compression loss.

FBD.
[/quote]


Ditto.

If the engine has good compression, the backplate is sealed, the carb is sealed at its base and there isn't a lot of fuel leaking around the front bearing, tearing it apart is a waste of time and it will void the warranty, if it is still in force.

You mentioned that you had a slit in a line and then said that wasn't the problem. Huh?

I said i had a slit, but i hcanged the fuel line. No leaks in the fuel line. Actually there is no air coming out of the tank. Its pretty much perfect. It just quits during verticle flight.

Have you checked that your fuel pickup in the tank isn't too close to the rear of the tank? Going vertical can sometimes stretch the fuel line enough that the orifice in the clunk is up against the rear tank wall. It is best to leave a 1/4" or more of space between the rear of the clunk and the rear tank wall.

Good luck solving the problem. Please let us know what it was that was causing the flame outs. TIA

Ed Cregger

I bought one of the original Tower .46 many years back and I also had a similar problem. For me the engine ran EXTREMELY hot even with 20+% Catsor. After consulting with the late great George Aldrich he suggested I put in a couple of the shims that the engine came with. Well, what do you know? The engine no longer ran hot and to this day the only evidence of that frustrating incident is the blue head is a bit lighter. This engine has run great ever since with awesome power and smooth, low idle. Try putting in some shims- that might help.

You said that it worked flawlessly on your trainer. I don't get the feeling that the problem is with the engine, but rather, something to do with your current set-up on the plane you have it on now. Can you give us more details about your current installation?

It is really sad what Tower did to a great engine. I originally sold this engine as the Raptor 46. It had a conventional carb and was the most powerful and user-friendly sport 46 available. It was made by GMS for their domestic Chinese market. Tower came in and got an exclusive contract for the engine and you now see the results. I bought a couple and no one that I flew with could ever get it to run right. I am no stranger to engines and I even got an older MDS 45 running pretty good. This engine never ran a full tank correctly. I think it comes down to the remote needle carb. My suggestion would be to buy a Thunder Tiger Pro 46 or a GMS 47.

For a sport plane for those engines, the Kaos is the one! Best flying plane I ever had.

I know how you feel with your engine dieing while vertical. I have a MDS 40 Pro that flew perfect on a morris su-di-ki 40 size. After a hard landing. [ Crashed while trying to land backward.....YES..... I would put the plane in a hover and kill the engine and backslide back to the ground and land. I made the flapperrons go up to make the wing achieve lift.] I mounted this engine on a spitfire and now it also dies when vertical. I have checked all the simple solutions. fuel lines, tank insulation, chunk, cleaned carb, mounted on a custom engine stand so I can move the engine in any direction while running. I have sealed off the carb. and presurized the engine to 5 psi to check for air leaks. With soap and water. No leaks found. I even put the tank off the spitfire on the engine stand. The tank is 3 1/2 in. away from carb and centered with the crank-shaft. The fuel line is 5 in long on the carb side and 4 in long on the pressure side. I drilled out the exhust fuel nipple on the pipe. I also cleaned out the exhust pipe spotless. It also has a new glow plug. I am running 15% nitro with 18% caster. I am also running a 10-8 prop. It use to run fine with a 13-4 and a 10-9 prop. Anyway I am keeping a eye on this collum to see what to do next. Thanks and good luck.