restoration PT-19 .049 engine advice needed

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

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

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

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

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!

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...

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

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.

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!

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

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