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restoration PT-19 .049 engine advice needed

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restoration PT-19 .049 engine advice needed

Post  Peter2000 on Thu Mar 17, 2016 3:28 pm

I'm a novice in everthing that relates to control line airplanes.
Situation is: Got my hands on a appx 20 year old cox PT-19. Plane is in a really good condition. However the .049 engine needs to be cleaned. The propeller can be turned though is sluggish. Piston moves up and down with this suctionish sound which I guess is a good sign. I was told engine has been fired up twice only and never been oiled with any after run oil.
Needle screw is stuck and can't be turned. The black plastic cap that goes on top of the needle screw is gone. This cap isn't really needed - right?
I need some advice how to get this engine up and running in order for me to fly this old PT-19.
I have follwing tools: a pair of Cox Engine Wrenches for .049 engines. A crankshat removal tool. A crankshat assembly tool and of cause a varity of screwdrivers etc
It will be highly appcreciated if someone here has the time to come up with a step by step guide how to clean an old PT-19 .049 engine.
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Re: restoration PT-19 .049 engine advice needed

Post  NEW222 on Thu Mar 17, 2016 4:13 pm

Not being an expert, I will help you out to do what you want the way I would do it. Firstly, remove the engine from the airplane. then remove the glowhead from the engine. Carefully remove the backplate from the engine. As I do not have an idea of what engine you have, I will do my best. If there is a fuel tank , it will come off in the last step with the backplate. Whichever engine you have, remove the reed and retainer from the engine. With the supplied wrenches, CAREFULLY try to remove the cylinder from the engine. If it comes off, great. If not, don't worry. You can try to heat the cylinder up then try again, or you could go straight to putting the engine in some fresh fuel and let it soak a while. After that you can try spinning it over and see how it goes. Same goes for the backplate, except DO NOT heat it up. Go directly to the soaking. Once the needle is removed, check the fuel passage for obstruction. You can squirt fuel through with a syringe or fuel bulb. I use compressed air and pins and needles to clean my passages. Once satisfied, reassemble the thing and run it. I have used fuel for cleaning, but I prefer my crock pot and antifreeze. But be careful if using the antifreeze in the crock pot as some plastics turn colors and harm can be done. I hope this helps you some.
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Re: restoration PT-19 .049 engine advice needed

Post  NEW222 on Thu Mar 17, 2016 4:14 pm

Also, there have been topics here on this already, and you can try a serech here.
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Re: restoration PT-19 .049 engine advice needed

Post  Dane Martin on Thu Mar 17, 2016 6:04 pm

https://youtu.be/QrIfYPcm6L8

https://youtu.be/Q3y-jiHbW5A

Take a quick look at these also. If these don't help, i can specifically make a video on disassembly, cleaning, all that. I can't remember if disassembly is covered.... Sorry. Been a little bit since i uploaded them
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Re: restoration PT-19 .049 engine advice needed

Post  Peter2000 on Thu Mar 17, 2016 9:24 pm

Thanks - I'll will unmount the engine from the plane and flush it with isopropyl alcohol as a beginning.
If the propeller and needle screw are easier to turn then something is right. Then I can wait taking the whole engine apart till I have flown it.

Of cause if I can't start it then an intensive engine restoration is needed.



Dane Martin wrote:https://youtu.be/QrIfYPcm6L8

https://youtu.be/Q3y-jiHbW5A

Take a quick look at these also. If these don't help, i can specifically make a video on disassembly, cleaning, all that. I can't remember if disassembly is covered.... Sorry. Been a little bit since i uploaded them
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Re: restoration PT-19 .049 engine advice needed

Post  getback on Fri Mar 18, 2016 9:37 am

Peter , the best thing to do while you have it off go ahead and do a cleaning of the complete engine I cant remember what product engine was on the PT- 19 ( can you take a pic and post of engine )? either way to save your self from doing it twice ! And if you have Hobbies #9 this is very good stuff and works fast ( Take apart and soak 20-30 mins. ) if not, Denatured alcohol works well and has less water than the other and want make the engine swell up and be hard to turn over till it drys completely . Assemble with light weight oil. getback Babe Bee .049
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Re: restoration PT-19 .049 engine advice needed

Post  Peter2000 on Fri Mar 18, 2016 12:13 pm

I'm away from my PT-19 for the weekend.

I'll start unmounting the engine on Monday and take pics of every step.
Kinda concearned of the needle screw and plastic back.




getback wrote:Peter , the best thing to do while you have it off go ahead and do a cleaning of the complete engine I cant remember what product engine was on the PT- 19 ( can you take a pic and post of engine )? either way to save your self from doing it twice ! And if you have Hobbies #9 this is very good stuff and works fast ( Take apart and soak 20-30 mins. ) if not, Denatured alcohol works well and has less water than the other and want make the engine swell up and be hard to turn over till it drys completely . Assemble with light weight oil.  getback Babe Bee .049
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Re: restoration PT-19 .049 engine advice needed

Post  roddie on Fri Mar 18, 2016 8:27 pm

Hi Peter, If your PT19 is 20 years old, it likely has what's referred to as a "horseshoe" back-plate. If there's anything wrong with it.. a replacement can be found at Cox International. My PT19 is an early-mid 1990's version which has this back-plate. Many Cox models used it.

On mine, there was a circlip retaining the reed. Yours may have the newer style plastic-cap. A new replacement would have the plastic-cap style retainer. A choke-tube is part of that package. It is separate.. and won't be used for the PT19.




The first photo shows the complete back-end with needle, reed, cap-retainer and gaskets. The snorkel/choke-tube won't fit this model.. but you can keep it with your spare parts. This back-plate has four holes for mounting to a plywood firewall.. although the PT19 does not utilize them. You can mount the engine on a balsa-wood model with an external tank later on down the road if you want.. and the firewall can be modified to fit that choke-tube. It makes the air-intake accessible to "choke" with a finger.. to draw fuel from the tank and up to the engine. I really like using the horseshoe back-plate on my balsa airplanes.

Hopefully yours is ok.. but it's no big deal if something's amiss. There is a needle-valve "seal" that's important. All the sealing/gaskets on the engine are important.. or it won't run consistently. The plastic "knob" that's missing from the needle is nothing to be concerned with. You will get used to adjusting/tuning your needle by "sound".

Your model likely has a left-hand propeller. It's a feature that Cox incorporated into the trainer-design. The reed-valve engine will run in either direction effectively. A left-hand rotation (clockwise from the front) creates a roll; away from the center of the circle.. helping to induce positive line-tension. This is very helpful for the beginner.. and more stable on a breezy day. The original prop was a 6 x 2 L/H. Check your starter-spring. It's probably a left-hand one. The stock L/H prop can be hard to find.. but Cox International has a 5 x 3.5 that would work as a replacement. Don't worry about that too much. You can swap the starter-spring and prop to R/H rotation if you have to.

I hope this been of some help. The engine itself is pretty durable. Be sure to use quality 1/2A glow-fuel.. and nothing else. I've found that "3-in-one" oil helps to loosen-up a sticky crank. You don't really need to remove the crankshaft from the case. It's good that you have the tools to do it though. Cleanliness on re-assembly and tight sealing of all gaskets will pay-off in ease of starting and steady running. A spare glow-head/gasket and prop are two things worth having in your flight-box.

If you have any questions at all, we will be glad to help!

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Re: restoration PT-19 .049 engine advice needed

Post  Mark Boesen on Fri Mar 18, 2016 10:53 pm

i hadn't seen it mentioned and if it was i'm sorry, but remember if you need to put some torque on the glowhead or cylinder, DON'T! Get the engine parts warm to soften the dried caster (glue) and you'll save parts from damage...
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Re: restoration PT-19 .049 engine advice needed

Post  RknRusty on Fri Mar 18, 2016 11:15 pm

None of the above advice is wrong. However, being the lazy type, and if it appears your engine has never been run hard and planted in the dirt, I'd just remove the glowplug and backplate, including the reed. Set the glowplug aside, and drop the rest in a jar of fuel for a couple of hours or overnight. Denatured alcohol is fine if you don't want to waste that much fuel. Then with the needle out, blow some brake parts cleaner or other solvent through the spraybar where the needle goes. Work the prop to loosen it up, oil it and put it back together. I would not remove the cylinder or the internals unless it looks old and dirty. Yours may be clean other than congealed castor oil. Should run like new.

Get some fuel with about 20% oil, at least half of which must be castor oil. 20-35% nitromethane works best.
sigmfg.com is a good source, and so is http://fitzfuels.com/index.php?id_product=1&controller=product

Good luck
Rusty

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Re: restoration PT-19 .049 engine advice needed

Post  Kim on Sat Mar 19, 2016 3:54 am

I'm with Rusty on this particular one: Less is more. With the spray bar clean, a good gasket under the head, and the reed unstuck, it ought to run like a pup.
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Re: restoration PT-19 .049 engine advice needed

Post  Peter2000 on Thu Mar 24, 2016 6:37 am

thanks a lot!



It has a horseshoe back plate and is intact though screws have sticky stuff residue on their heads. That will easily come off.
I dismounted the engine - took off the back plate. Piston goes up and down like a charm when turning propeller.
No dirt or sticky stuff inside the engine. Back plate gasket seems OK.

Later today I'll carefully take off the glowhead and propeller and dump metal parts in denatured alcohol over night.
My only worry is the needle screew. It is stuck in the plate and cannot be turned. Might try with a little alcohol on a pipe cleaner.



roddie wrote:Hi Peter, If your PT19 is 20 years old, it likely has what's referred to as a "horseshoe" back-plate. If there's anything wrong with it.. a replacement can be found at Cox International. My PT19 is an early-mid 1990's version which has this back-plate. Many Cox models used it.

On mine, there was a circlip retaining the reed. Yours may have the newer style plastic-cap. A new replacement would have the plastic-cap style retainer. A choke-tube is part of that package. It is separate.. and won't be used for the PT19.




The first photo shows the complete back-end with needle, reed, cap-retainer and gaskets. The snorkel/choke-tube won't fit this model.. but you can keep it with your spare parts. This back-plate has four holes for mounting to a plywood firewall.. although the PT19 does not utilize them. You can mount the engine on a balsa-wood model with an external tank later on down the road if you want.. and the firewall can be modified to fit that choke-tube. It makes the air-intake accessible to "choke" with a finger.. to draw fuel from the tank and up to the engine. I really like using the horseshoe back-plate on my balsa airplanes.

Hopefully yours is ok.. but it's no big deal if something's amiss. There is a needle-valve "seal" that's important. All the sealing/gaskets on the engine are important.. or it won't run consistently. The plastic "knob" that's missing from the needle is nothing to be concerned with. You will get used to adjusting/tuning your needle by "sound".

Your model likely has a left-hand propeller. It's a feature that Cox incorporated into the trainer-design. The reed-valve engine will run in either direction effectively. A left-hand rotation (clockwise from the front) creates a roll; away from the center of the circle.. helping to induce positive line-tension. This is very helpful for the beginner.. and more stable on a breezy day. The original prop was a 6 x 2 L/H. Check your starter-spring. It's probably a left-hand one. The stock L/H prop can be hard to find.. but Cox International has a 5 x 3.5 that would work as a replacement. Don't worry about that too much. You can swap the starter-spring and prop to R/H rotation if you have to.

I hope this been of some help. The engine itself is pretty durable. Be sure to use quality 1/2A glow-fuel.. and nothing else. I've found that "3-in-one" oil helps to loosen-up a sticky crank. You don't really need to remove the crankshaft from the case. It's good that you have the tools to do it though. Cleanliness on re-assembly and tight sealing of all gaskets will pay-off in ease of starting and steady running. A spare glow-head/gasket and prop are two things worth having in your flight-box.  

If you have any questions at all, we will be glad to help!



Last edited by Peter2000 on Thu Mar 24, 2016 6:55 am; edited 1 time in total
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Re: restoration PT-19 .049 engine advice needed

Post  Peter2000 on Thu Mar 24, 2016 6:43 am

I will be the lazy type waiting to disamble entire engine apart until absolutely necessary.

The reed seems to need a little cleaning - it is the star shaped one. Might be difficult to replace.
Fortuneatly both reed and spring is OK.

RknRusty wrote:None of the above advice is wrong. However, being the lazy type, and if it appears your engine has never been run hard and planted in the dirt, I'd just remove the glowplug and backplate, including the reed. Set the glowplug aside, and drop the rest in a jar of fuel for a couple of hours or overnight. Denatured alcohol is fine if you don't want to waste that much fuel. Then  with the needle out, blow some brake parts cleaner or other solvent through the spraybar where the needle goes. Work the prop to loosen it up, oil it and put it back together. I would not remove the cylinder or the internals unless it looks old and dirty. Yours may be clean other than congealed castor oil. Should run like new.

Get some fuel with about 20% oil, at least half of which must be castor oil. 20-35% nitromethane works best.
sigmfg.com is a good source, and so is http://fitzfuels.com/index.php?id_product=1&controller=product

Good luck
Rusty
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Re: restoration PT-19 .049 engine advice needed

Post  getback on Thu Mar 24, 2016 12:10 pm

Ok Peter , since the engine turns over good / just soak the back plate then try and remove the needle may need to heat some with a hair dryed / when out take a piece of fuel hose and try blowing air through the NVA (needle valve assy.) use your mouth air pressure with hose hooked to the NVA, if it will , stop up the other side and try blowing if it does then the spray bar hole is clear (very important) if not soak some more or use carb. cleaner to clear by spraying into the NVA. I would remove the circlip holding reed in CAREFULLY remove the reed as not to bend it clean the green off with is old fuel residue (when this is done put back together MAKE SURE THE CLIP IS PUT IN SO THE TANG IS PERTRUDING OUT AS NOT TO PINCH THE REED!! This should get you going if any questions just ask , you can get reeds new but not that style . I hope this helps . Eric Very Happy
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