Pee Wee - Play in prop shaft?

Thank you very much for info and taking the time to check. I think Im good!
I believe there is about 3 or 4 flights on this motor, I cant remember. I had build a gillows piper cub, very fragile model but flew very well, until it didnt. Engine has been in my garage ever since, now I got the bug again.
Hopefully new fuel will fire it up, if not I will take it completely apart to inspect.
Thanks again.

Jim and others will know much more about the tolerances and such for the Pee Wee 020 as I don't own one. All the same I would not expect that to stop it from running, although it is probably worth fixing as Jim suggests.

Have you checked your glow plug and does it glow strongly? it should. try putting some fuel in through the cylinder ports with the needle valve closed and see if it fires. It should fire on a prime if the glowplug is all good. If it does fire and run a bit on a prime the glow and fuel and core engine are ok and it is the fuel path causing problems most likely. That is to say, fuel not getting from the tank into the engine. I cannot help you with the fuel path on a Cox engine with a builtin tank as I dont own any with the builtin tanks.

Hope it all sorts out for you.

Yabby

Glow plug seems to be good, I actually did exactly what you suggested, it fires and tries to run only on the prime fuel. So not getting fuel from tank or could this be 30 yo old fuel not burning correctly? Ive seen other posts here with guys starting engines on very old fuel. My Cox fuel smelled really old though and there was some separation in it before I shook it up. Probably should take a look inside, maybe something is gummed up in there, it was drained before storage and as mentioned has very little time on it. Hoping it would be as easy as new fuel.
Thanks

Another thing to check is the fuel passage regulated by the needle valve. Cox instructions instructed the modeler to close the needle valve and open it 2 1/2 turns. But it is pretty easy to break the tip of the needle valve off in the backplate if the needle valve is tightened too much.

Should that be the case you would probably need a new backplate and needle valve as the tip would be nearly impossible to remove.

Saw info on that here tonight so I checked, needle valve is good. There is no markings on this engine, it came in a box not plastic wrap. Not sure of year but I think it was one from last years in production. This might be a stupid question but do you know if there a rubber fuel pick up line inside the tank on the Pee Wee? Ive seen some blow ups of 020 but not sure if they were Pee Wee later model.

All the Pee Wees that I have used a clear flexible plastic pickup tube. Not rubber.

Ok.
Might as well just take the thing completely apart while waiting for fuel to arrive.
You've been very helpful.
Appreciate, it.

im a big fan of the sig 35%

good luck!

Took it apart, everything looks brand new in there. Im going back to fuel quality.
I will update after new fuel arrives.

cstatman, thats good to hear, unfortunately Im in CA., cant find castor fuel anywhere out here so I was so happy to find at Sig. They actually recommended the 25 or 35%, 35% was all they had in stock, everything else is on backorder so Im glad it works for you.

If your old fuel was separating then that's probably the problem. Fuel separation is usually caused by it absorbing water from the atmosphere. If you shake it and it goes cloudy then it is most certainly water. Don't throw it out. It will be good for washing engines/parts.

New fuel/old fuel won’t make a bit of difference in fuel draw. Your assumption that it’s not drawing fuel because it only runs on prime is correct. If it runs on prime the fuel is good enough for ignition.  

If this engine has sat for decades, then then it needs to be completely disassembled and cleaned thoroughly, to include the backplate/needle and all passageways. You also should purchase a rebuild kit from CI or Exmodelengines. This will include a new reed, venturi gasket and pickup tube. While yours may appear functional, they do degrade when sitting. It’s cheap insurance and beats having to continually disassemble it to look for problems.

The Pee Wee takes a little more effort than a Babe Bee to get it to run well, it’s easily prone to air leaks which is a killer to getting a good clean run. Be meticulous and ask questions and you will be rewarded for your efforts.

Ron

Thanks for info. I ordered rebuild parts. Ill try to send pics of inside the engine later today. The only thing I see that looks worn is the venturi gasket, hard to tell with my eyes and a bad magnifying glass. Could this alone cause an air leak and symptoms of no fuel? Passageways also appear clean.
In the meantime do you think I can use some 20% nitro (Traxxas TopFuel for RC cars) to temporarily test this motor for a short period or is that a bad idea?

20% nitromethane is not a problem for the Pee Wee. The more the better up to about 35%. However, I've read that R/C car engine fuel has less oil than the fuel sold for airplanes and synthetic oil often used in that stuff will wear the piston ball and socket joint rapidly. One or two short runs shouldn't matter but it would be a good idea to add some plain castor oil to the fuel if you can find it. I used to use castor from the drugstore and it worked fine.

It sounds (to me) like a "stuck reed". The reed can stick to the seat if the engine is put away (for a long time..) without being cleaned. A simple test (tank assembly removed) to check the reed-function, is to wipe the assembly with a clean rag, hold it to your mouth and proceed to blow and suck. You don't have to use much force to do this. Blowing (positive pressure) should feel restricted. Alternately; sucking" (vacuum) should flow freely. Sometimes a reed can be creased.. or deformed.. and as a result; won't seal properly. You might hear an audible "squeak" and less resistance when blowing. That's a sign of a faulty seal. Try a different reed to see if it seals better. If there's a circlip type retainer, check to see if "it" is positioned properly. The circlip should sit in a groove and not restrict the central area of the reed from opening/flexing.

I'd wait for the Sig Champion 35.. or run the old Cox fuel. If it fires-off on an exhaust-prime.. then it'll run your engine. You should filter/strain the old fuel though. Don't run your garden-variety car-fuel in your Cox engine. The Cox and Sig Champion fuel blends have castor-oil. Your engine was designed to require castor-oil in the total-oil package, for a long service-life.

I've been running Sig Champion 25 and 35 since Cox fuel became non-commercially available.

Below are some Cox fuel-batch formulations. Note the castor-oil to synthetic-oil ratios.

I really appreciate all the input, this forum is priceless since information is so hard to come by these days on this engine. All of you have been so helpful, nice to know there are good folks out there.
Tried to run today again on the 20% nitro, no luck, same symptoms, not getting fuel from tank. Took apart again figuring there was a block in fuel pick up line, couldnt seem to blow through the line so I removed. Broke the dang plastic tube "coupling end" when trying to remove, only to find that there was no blockage in the line. More parts ordered, hopefully the fuel pu line from EX works, got new spring too. Need to back up and figure this out before destroying more good parts.
Roddie, I will check for stuck reed, if it was that simple, I wish I would have tried that first, cant test again until pu line comes but I will update.

Reed spins freely. Didnt do the air pressure test yet. Little frustrated, will try tomorrow, thanks again.
Figured that Traxxas fuel wasnt good, just wanted to hear the thing run.

firstwordisee wrote:Reed spins freely. Didnt do the air pressure test yet. Little frustrated, will try tomorrow, thanks again.
Figured that Traxxas fuel wasnt good, just wanted to hear the thing run.

Sorry that you're still having trouble. You mentioned the fuel pick-up line.. and trying to remove it. You stated that the plastic-tube "coupling end" broke-off. I have found (with my Babe Bee .049's) that if the original clear-vinyl pick-up was in place; it was usually hardened and brittle from age. The earlier pot-metal tank/back-plates had a little "hose-barb" that would help to secure the pick-up line from falling off. The newer PLASTIC .049 tank/backplates don't have that barb. There's just a straight tube for connecting the pick-up line. I was wondering if your Pee Wee .020 tank/back-plate is like this.. (is plastic?)

I've never had a Pee Wee engine.. but the early ones are basically a scaled-down Babe Bee.. of which I've had several. Makes no difference whether early or late with an integrally-tanked Cox engine; having the tank-assembly seal-correctly is key. When I say "seal"... I mean; no air-ingress other than venturi, and no fuel egress (leaks from the tank-bowl). Use new/good gaskets (case and venturi).

By the way; I prefer and use silicone glow-fuel-tubing.. (DUBRO) and have used their sm. size "blue" silicone.. but it looks like there's a new product. Dubro glow-fuel tubing  

You mentioned attempting (albeit unsuccessfully) to blow through the fuel pick-up line prior to removing it. A better way to check the flow is to use a syringe. FOR SAFETY: Put the part in a clear plastic bag with fittings to apply pressure via the syringe. REMOVE THE NEEDLE.. and apply slight pressure to purge the venturi and other passages with solvent.. (old filtered fuel is great for this) If it's possible to "backflush" (with syringe-suction).. it may help to further clear the passages. Let's say that you source some vintage (2nd hand) Cox .020 Pee Wee parts/engines. You'll want to clean them properly before putting them into inventory.

There's another area that's worth examining. It's the depth of the threaded bores in the crankcase, which accept the four machine-screws which attach the whole tank assembly. It was fairly common for these bores to NOT be threaded deep enough. This could result in screws that don't tighten sufficiently. The fix is obtaining the proper "tap-tool" to cut some threads a little deeper into these bores. The "Q.C." on these engines suffered in later years. You can be an expert mechanic... if you know what to check for.  

The Cox Bee (.049) glow-engines have 2-56 threaded-bores for the tank/back-end. The Pee Wee's may be the same.. I'm not sure about that.

Best of luck!

Roddie,
Good info, thanks for the tips.
All metal, and there is a flange for securing the pick up tube. Tube was hard and brittle. Thats why Im hoping the new part fits over that flange, EZ identifies them for pee wee 0.20 so maybe they are softer material than can slip over.
Everything on engine fits snuggly.
On the baby bee does the venturi gasket seat inside, meaning flush with the orifice surface, if that makes sense. On my pee week it is flush, I dont see how to remove except to dig it out and not sure if this is correct fitment or some of it rotted away, and if this could be the "air leak". Like I said it looked brand new inside (before I started wrestling with the pick up line anyway ...LOL), but Ill go ahead and rebuild when parts get here, should be able to narrow it down then.
On a good note my Dakota kit got here today, hopefully I can start that next week as I will be gone for a few days.

firstwordisee wrote:Roddie,
Good info, thanks for the tips.
All metal, and there is a flange for securing the pick up tube. Tube was hard and brittle. Thats why Im hoping the new part fits over that flange, EZ identifies them for pee wee 0.20 so maybe they are softer material than can slip over.
Everything on engine fits snuggly.
On the baby bee does the venturi gasket seat inside, meaning flush with the orifice surface, if that makes sense. On my pee week it is flush, I dont see how to remove except to dig it out and not sure if this is correct fitment or some of it rotted away, and if this could be the "air leak". Like I said it looked brand new inside (before I started wrestling with the pick up line anyway ...LOL), but Ill go ahead and rebuild when parts get here, should be able to narrow it down then.
On a good note my Dakota kit got here today, hopefully I can start that next week as I will be gone for a few days.

The new pick-up tube will likely fit fine. Is there a tiny metal "spring" shown/included with the pick-up? This was originally placed inside the tubing. Its purpose has been discussed/argued here more than once. Some say that the spring prevents the pick-up tube from kinking.. and others say that it helps to disperse any air bubbles that could form in the fuel-bowl.. and still.. others say that the spring creates a capillary-action to assist in drawing fuel through the pick-up tube. I must say that I agree with "all three" theories.

Regarding the venturi gasket; An aged/old one tends to harden and flatten-out. At this point it must be replaced. I have found that they tend to cling to the venturi-tube in the tank-bowl. I've used a toothpick to remove them.. but sometimes they're stuck pretty good if they're old. Be careful not to gouge or scratch where the gasket seats.

I made my own gaskets. See the photo below..



They just have to work.. and mine are made from retired "Playtex" kitchen glove "cuff" material.



Certain to last at least one season of running.



You'll want to pay attention to certain areas of timely maintenance on your engine; depending of course on your schedule.

forgot to wish you good luck with the "Dakota" kit! That's a great catalyst for getting the engine squared-away!

Thanks Roddie, got a lot done on the Dakota this weekend, posted in the build thread with some questions. Also thanks for the additional tips, looks like I got a package today from EX so rebuild will happen soon.

I'm sure that you'll get that Pee Wee all set to go!