Firehawk153

I've been trying to start a Webra .50 engine that hasn't been cranked in about 10 years and I'm not having a lot of luck. Since the engine hadn't been run in 10 years, I performed the following steps:

1.) Used an eye-dropper to apply Murphy's Mystery oil to all the components of the engine I could get to without taking it apart
2.) Unstuck the throttle; wouldn't budge at first but I applied a little heat to the dried-fuel-caked throttle and got it moving again
3.) Pulled out the glow-plug and verified that it still worked
4.) Pulled off the fuel tank and sumerged it in some water; no leaks on the tank or on the tubes
5.) Trimmed the ends of the silicon tubes that run from the tank to the carburator so that they would fit snugly on the connectors
6.) Carefully removed and cleaned the high-speed and idle-speed needles and placed them back into the engine.

The only half-way success I've had with starting it is by doing the follwing steps:

1.) Open the high-speed needle 2 1/2 turns
2.) Open the idle needle 2-3 turns
3.) Open the throttle 1/2 to 3/4 of the way
4.) Prime the engine
5.) Attempt to start

If I'm lucky, the engine will run for maybe 2-3 seconds then it will die. I've tried opening both the idle and the high speed needle less, opening them more, and still no luck getting this engine to stay lit. I've also noticed that when I flip the propeller (after I've choked the engine and gotten the air bubbles out) that the fuel doesn't appear to be moving through the tube to the high-speed needle. Is it just moving at such a small rate that I wouldn't be able to see it? I checked for leaks on the tank so I'm positive that the tank isn't leaking. Do I just need to take the engine completely apart and clean it?

One thing though; I'm using a bottle of fuel that is about 10 years old itself. It has stayed sealed in its bottle and has remained in an air-conditioned shop for the past 10 years but I guess its a possibility that the fuel itself is old.


Any suggestions or help would be greatly appreciated!

Thanks!

Firehawk153

AlexF

I'd start by trying new fuel and glowplug; no need to introduce more variables. I've definitely had cases where a glow plug glows, but doesn't run right. Also, if you leave a sealed plastic container of fuel on a cement floor for a long time, sometimes you'll notice wet nastiness under it when you pick it up. *Something* happens to it while it's sitting there.

Depending on your setup you might not draw fuel by flipping the prop, but you definitely should if you choke the carb while you flip it.

If the number of turns you're giving the needles don't come from instructions for your particular engine, play around with them. 2 1/2 turns is typical, but if nothing else is working try 4 or 5. No harm done (just don't hydrolock it, but you're suspecting that it's not drawing well enough now.)

Have you got a local engine guru to play with it yet? Often it's obvious when an engine is starting way too rich or too lean by listening to it.

How do the bearings and compression feel?

If you want to take it apart and clean it, it certainly wouldn't hurt. Crankshafts and bearings tend to rust a *lot*.

Pilot Chad

My Feedback: (4)

This COULD be an intake leak also. Make sure the following are tight,

Needle valve
Backplate

If they aren't you could be getting no fuel and alot of air

piper_chuck

My Feedback: (12)

I second the recommendation for a new glow plug, I use OS #8. It would also be good to get some new fuel. Once you get it running, you can go back to trying the old fuel. Attach a piece of fuel line to the carb and blow through it to confirm the spray bar is not plugged. While blowing, close the needle to confirm it seats. Do the same at idle to confirm the idle needle is open enough.

If the engine was working when it was put away, you should not need to disassemble it. More problems are caused by improper reassembly if you've never torn down and rebuilt an engine.

Fuel usually does not move through the line when you're flipping it to start. In fact, on some setups, after the prime the fuel goes back into the tank, but as soon as the engine fires, the line is full again. Make sure you get a good prime.

When priming the engine, open the throttle all the way, and do not connect the glow driver. After priming, close the throttle more than the 1/2 to 3/4 you mentioned. I have a few engines that just won't start with the carb opened that much. I usually start my engines with the throttle at idle, or perhaps fast idle, setting.

Do you have the muffler on, and are you running muffler pressure?

Dr1Driver

1. Is MM oil methanol based or patroleum based?
2. The carb probably needs to be completely taken apart and thoroughly cleaned.
3. Replace the glow plug.
4. Replace the fuel tank.
5. Replace the fuel lines.
6. OK.

1. Close the HS needle to about 1 1/2 to 2 turns.
3. Open the throttle all the way to prime. Webras usually take 4-5 flips.

Replace the fuel. Give the engine a fighting chance with NEW stuff, not cleaned-up old. I'm guesing the old fuel is a big part of your problem.

Dr.1

bubbagates

My Feedback: (32)

You mentioned that you applied heat to get the throttle body to start moving again. It's possible, depending on the amount of heat you used that you melted/warped the O-ring under the carb and now have an air leak.

I am also assuming that you get the 2 -3 seconds of run time after a prime. That is what makes me believe an airleak. A new glow plug certainly would not hurt.

Firehawk153

Okay, now I'm really confused...[]

Ordered new fuel in the mail, Wildcat Premium Xtra 10% Nitro, replaced the glow plug and now the thing won't even kick like it even WANTS to start. Before I could get it to run for about 3-4 seconds but now I've got nothing. Took out the new glow-plug (noticed that it was slightly shorter than the old one) replaced the old one and still nothing. Again, both glow-plugs light up when I put the battery to them.

The Marvel Mystery Oil is Petroleum based (use in in my car/lawnmower; damn fine stuff but maybe not for glow engines ). I did flush out my engine with the fresh fuel to try and get rid of all of the residue from the marvel mystery oil.

It just seems to me that I now have a problem that is somehow different than the original problem I was having. At least before I could prime the engine and get a few seconds of run-time (and I could do this consistently).

Bubbagates, I noticed that the throttle arm had a single o-ring that appeared undamaged so I'm guessing that the o-ring under the carb would be okay as well. I inspected my high-speed needle and it appeared to be in perfect condition, it didn't have any damage on the end of the needle. I would rather not take the engine apart but if you guys think that it warrants it then I will. I have a small bit of a mechanic background so I know to handle the disasembly and reassembly but all my research points to only disassembling the engine if I have to.

piper_chuck, I do have the muffler on and I'm running with muffler pressure. The muffler gasket is present and accounted for, no damage.

BTW, should I be using a dedicated glow battery to start the engine? I have been using this little plastic battery mounting that came with a Cox engine starter set from about a decade ago that uses 2 D size batteries to try and crank the engine. Should I just go ahead and buy a glow battery or are the two D-size batteries providing enough juice?

Thanks guys for all your help so far!

Firehawk153

Firehawk153

BTW, Alex, compression feels a little weaker than it really should to me. When I flip the prop it doesn't take that much pressure to flip it through compression. Could it be possible that I didn't put the glow-head back on tight enough? I secured it firmly but I didn't overtighten.

Firehawk153

bump

AlexF

If you're using one of the cross glow plug wrenches (the ones with four tips for different sized plugs, of which you only ever use one) you can crank down fairly hard on it. Still, I doubt being slightly loose would keep the engine from firing at all. I've actually started higher compression engines with the plug finger-tight so the starter could turn it over easier.

On your funny glow starter, if those D batteries are in series, they should light up the plug like a torch. Actually I'd expect them to burn it out before too long. If they're parallel I'd guess they'd do it, and if they go through some bit of electronics I've no idea. It's worth borrowing a regular glo starter from someone at the field to see if it helps.

Are you sure you're still drawing fuel? If you hold your thumb over the carb and flip the prop, it should get your thumb wet after a few flips.

Most importantly though: what has your local engine guru said about it? Ears play a huge part in debugging these things.

jaka

Hi!
First of all : Take the engine apart and change those ballbearings if you don't have done it already!
An engine that has been sitting for 10 years is more than likely to have old castor oil goo in the ballbearings and that is stopping the crank from moving freely.
I don't say that the engine won't run if don't do the above but it sure will run much better and will hold up much better if you do.
Webra .50??? I don't think Webra manufactured any .50 engines 10 years ago...are you sure it isn't a .40 or a .60 engine? Well it dosen't matter really, as it should still run.
Put on a 11x6 or 12x4-12x5 APC prop and do use a Enya 3 or Rossi 3 glowplug, the Rossi 3 glow plug is what webra uses as their standard glowplug for the .40 engine.
Use 5% nitro, Not more!
See to that you use adequat glow power! A small 1,2 V Nicad is not recommended! A 12v, 12A lead acid MC battery is what I use myself.

Regards!
Jan K
Sweden

bruce88123

JAKA, surely you can't be suggesting that he connect a 12 volt battery directly to his glow plug as your post suggests. The plug would vaporize immediately. I strongly suggest you get to a model field where there experienced modelers available to assist. I am sure they will have all of the do-dads to loan you in getting the motor started. Once running, you will be able to better proceed on your own. Do you have a club in your area or do you even know how to find one?

ICE_MAN

JAKA...

A 12v 12A Battery will instantly blow the plug! The element will be shot across the room!


I have tried this with a 12v 7A battery! I know

bubbagates

My Feedback: (32)

I just caught up on here. If it will no longer run after a new plug and fuel then I still think you are having an airleak issue. But you also mentioned that it does not seem to make allot of compression and being that the engine sat around for a long time, maybe it's just time to tear it down and rebuild it. It's not that tough.

To make matters worse, We have a senior member at our club that has a brand new Supertiger 75. When you flip this thing cold it feels like there is not compression and will not start at all by hand propping it.

Once we put an electric started to it, it kicked over. We then got it tuned and it's been a screamin' little banchie ever since, but it will not hand start.

jaka

Hi!
Yeah! I know, I know...12V to the glowplug is a No, No...of course meant 12V AND a glowdriver to power the glowplug...took things for granted...

Regards!
Jan K
Sweden

Firehawk153

Well, I might have figured out something. I took the engine apart tonight and noticed that there was no backplate gasket. It seems at one time there was one but all that was left was this oily gunk. I just got a rag and wiped it off easily and cleaned it. I looked at everything else and the rest of the engine looked like it was in good shape. Could the lack of a gasket be part or my problem?

jlguru

IMHO... Not one of my various engines have a gasket on the backhead ... so I don't think that's an issue.

However, one thing that hasn't been mentioned yet (though it has been alluded to) is that sometimes the pressure tap on the muffler can get clogged w/ old fuel residue thus preventing the exhaust from pressurizing the tank. Blow through the pressure tap to make sure it is clear, and if there is a restriction just run a wire or small drill bit through the tap to clear it. This would explain your original condition (running briefly w/ a primed carbeurator then dieing). You can also prime the carb by blowing through the fuel tube that attaches to the muffler (pressurizing the fuel system by 'mouth') and see if fuel is reaching the carb. This also fills all the fuel tubes for that "first start".

Your initial complaint said that the motor would only fire at about half throttle(?) ... this would suggest that the low end needle is remaining closed until you advance the throttle. One way to set the initial low end needle setting is to position the carb at an idle position (perhaps 3/32 inch opening), blowing through the fuel line that attaches to the carb and listening for air escaping into the carb body. Close the low end needle, then while blowing, open it until you begin to hear air hissing in the carb body. Close the high end needle, then open 2-3 turns. If you have fuel flow and a functioning glow plug, the sucker should at least start. When I've fiddled w/ the needles and nothing is working, this is how I return to a base line starting point when tuning a motor. . Good luck ...

Live long, and prosper
Jerry L. Gubka

Firehawk153

Still no luck. I replaced the glow-plug with a spare that came with the plane, not sure what brand of glow plug it is but it fits.(the plane is a friends of mine's dad's plane; he hasn't flown it in 10 years. He gave me the plane and all the spare parts he had bought for it.). Also, the glow plug that I took out of the engine and the one I replaced it with both have idler bars on them. Could the idler bar be causing me problems?

Whatever the outcome I'm going to order some OS #8 glowplugs as spares (I just bought a Nexstar Select and If nothing else I'll keep them for spares for the Nexstar) and I'm going to order a new spinner for the engine. When the guy gave me the plane, he said he had broken the spinner trying to start it with an electric starter. All I've been using up till this point is a chicken stick so I think I'm going to order a new spinner for the bird (Aluminum? Plastic? does it make a difference?) and try it with the electric starter.

Question about compression; When I was replacing the glow-plug I spun the prop around with the glow-plug out of the cylinder head and it spun around quite freely (made probably 3 strokes on its own before it stopped). Does this compression sound a bit too loose or can it vary from engine to engine?

I checked the muffler and it was clean, nothing clogged. I also blew on the pressure line off of the muffler and fuel moved toward the carb; didn't see any problems.

BTW, jaka, I'm not sure if its a Webra .50 or not. The reason I called it that is because it has the number 50 stamped on a plate on the cylinder. I just assumed () that meant a .50 displacement.

AlexF

I've never had an engine that would freewheel through tdc even without a glowplug. Could be this one's different though..

britbrat

Are you sure that fuel is actually getting through the NV assembly? Cleaning the needles is a good thing to do, but did you clean out the jet? Try passing a "cats whisker" wire through the jet, or try blowing through it.

You probably do need the backplate sealed. Use a thin film of silicone sealant on the mating surface of the backplate.

Try removing the muffler & squirting a bit of fuel into the cyl through the exhaust port, then attempt a start. If it fires, you are simply not getting any fuel into the crankcase through the needle valve assembly.

Firehawk153

I know its been a while, but I've got something of an update...


I replaced the fuel tank, fuel lines, glow plug (with an O.S. #8 glow plug) and spinner with all new components. This time I used the electric starter on the engine to no avail; the engine still wouldn't fire. The engine seems very loose I don't feel much compression at all when I flip the prop with my hand.

Anyway, if anyone has any other ideas, feel free!

bruce88123

I'm assuming that you have tried your glow ignitor onthe plug outside of the engine and assured yourself of a good quality "glow"?

Have you taken a few drops of fuel and placed it directly into the open carb to prime the engine?

Although I don't like to do this on a regular basis. A small squirt of Ronsonol lighter fluid in the carb also works and it light off even better than standard fuel.

When turning over the motor (using elec starter) with the carb wide open, can you see a fuel spray in the carb?

bruce88123

Does this look like your engine?
http://www.webra-austria.at/motor.ph...r=AERO&lang=EN

This is an ABN engine without a ring. You should have a fairly tight/snug fit between the piston and sleeve near the top of the stroke. If not, it is possible that it is just worn out and needs parts.
Looking into the exhaust port, can you see a ring on the top of the piston?

bruce88123

http://www.webra-austria.at/download/motor_e.pdf

http://www.webra-austria.at/motor.ph...e=AERO&lang=EN


Note: the bottom 2 lines are one URL and need to be combined in address window.