Varnish seize?

A Davis Diesel brush is probably the next best tool to the reset tool. It quickly removes the varnish and places micro scratches in the cylinder walls in a cross hatch pattern which does increase rpm's. Run the brush a few times in the cylinder and wash with soapy hot water. An old toothbrush with the sides slighty rounded allows it to get inside the cylinder to really scrub it well. Ken

Brass .45 cal. brush from a gun store works very well. Use Hoppes #9 solvent also available at gun shops or sports centers.

My wager would be with Rusty particularly in view of where the
'tight' spot is.. The wrench has burred the bore.
Just to confirm, I have burred a bore in this manner in the
Past

In the event the bore did indeed get burr, it can be fixed. I've repaired many that had the wrench treatment where the cylinder had no flats and the wrench caused the damage. If you use K&S 3/8 tubing, I cut a piece about 6" long. You then wrap Scotch tape around the tube once sometimes twice. I find the blue painters tape to work with one wrap as well. Insert the brass tubing through the cylinder with the tape exiting the bottom of the cylinder. The inside of the piston skirt is tapered. Put the conrod into the tube and push the piston skirt onto the tube and the tape will hold it pretty snug. While drawing the piston up into the cylinder, it will be upside down in the bore with the skirt coming up to the glow plug landing. I mix a slurry of rottenstone and oil and place a drop or two onto the skirt via the exhaust slots. You can use Brasso or even mild polish like Dupont "7 Rubbing compound or even A fine chrome polish. You turn the brass tube while working it up and down bringing the skirt not to high in the bore as your just using the skirt to rid the cylinder of the burr. The skirt has very little value other than keeping the piston running true in the bore. Relieving a bit of the skirt will even possibly give you a higher performance. I do this with many of my speed planes. If the tube comes out while attempting this, wrap another layer of tape on the tube. Make sure all is washed real well in hot soapy water. The 3 items I described above will breakdown using water. I've saved many cylinders this way. Chrome polish is a bit harder to rid the cylinder of for example, Mother's. I use a nylon bristle brush to scrub all media out and this is a must as it can retain itself on the cylinder walls creating a lapping compound. The area of attention is the bypass ports as they can load with the polish. Ken

Rottenstone? What is it and where do I find it?

My supply was given to me by Larry Scarinzi. Duke Fox had given him a considerable amount back in the 60's. A few of us actually had asked for some and he filled up some 35 mm film canisters with it. In fact, this may be true to this day, When Fox tests their engines prior to sale, they use a fine powder with a brand name Lusterox. I believe this is what I have. It's a very fine abrasive and when the engine was running they dusted a bit into the intake to expedite break in. I've seen this done with Cox Tee Dee's as well back in the early 80's the combat guys were doing this. I've used the Dupont rubbing compound repeatedly and it has worked real well. I find it abrasive enough to do the job and not abrasive enough to over do the job. Seeing that the cylinder in question is already in not so up to par quality, I would certainly give it a try. I did Google rottenstone and it revealed the abrasive powder. Ken

Varnish yields well to Hoppe's #9 Gun-Cleaning sovent.

Give your engine a good soaking/cleaning then see how it runs after.

JPvelo wrote:Rottenstone? What is it and where do I find it?

Rotten Stone is a fine polishing compound when mixed with oil or water that is used for wood.

A finer form is known as Tripoli and is used to polish soft metals. It is available dry or in a wax and/or grease mix.

There is a very dark form in hard wax used to "charge" buffing wheels.

If you use this make VERY sure you remove all traces of it or it will continue polishing when you run the engine.

if you use some synthetic along with castor, varnish will not form as easily.

George

[quote="RknRusty"]

JPvelo wrote: Otherwise you get a burr on the port edge that makes it stiff until you find and remove the burr.

really wish i would have read this 2 hours ago... now in sanding that burr out by hand

Hoppes #9 and a nylon .45 caliber brush. Thanks guys.

Buy your Hoppe's #9 by the quart and save yourself some $$$$. I use it for all sorts of cleaning task. I buy mine in-store at Cabela's.

Besides going to Cabla's like going to a candy store for boys.

Okay, just had the same thing happen last night. Turns out I am mushrooming the piston when I use my reset tool. Have only used it twice and has happened with both pistons.

JPvelo wrote:Okay, just had the same thing happen last night. Turns out I am mushrooming the piston when I use my reset tool. Have only used it twice and has happened with both pistons.

I've ruined every piston I've tried. I was using a medium tack hammer on a flat anvil and tap-tap-tapping while rotating the piston. After 50 or so licks, nothing was happening so I increased my force. One that didn't mushroom, lost half of its SPI, as did some of the others. I quit doing it. Since then, I've been told to use a heavier hammer, but I haven't tried it yet.

Since I don't run most of my engines over 20K RPM, I don't worry about it and they run fine. Over time I suppose it could wear through from lateral movement of the ball in the socket. Many people imagine it's an up and down slop, hammering during the piston stroke, but I don't think there is actually ever a time when the rod ball isn't being pushed tightly against the underside of the piston. Sure, the lateral motion is wasted energy but I doubt if it's ever even noticeable. I will try it again with a bigger hammer, but not on anything I treasure until I find I can do it successfully.

Okay everybody, you may pile on now.

Rusty:

We've both been dealing with the same problem: seized engines.

Yesterday I received a brand-new TD .051 that was seized solid. An overnite soaking in Hoppe's and the application of mild heat from my Weller butane "mini-torch" this morning AND voila! The engine freed up fine, the cylinder loosened and ditto the backplate and cylinder head.

The mini-torch came as an accessory with my Weller soldering torch. At no point did I apply force to free these parts.

SuperDave wrote:Rusty:

We've both been dealing with the same problem: seized engines.

Yesterday I received a brand-new TD .051 that was seized solid. An overnite soaking in Hoppe's and the application of mild heat from my Weller butane "mini-torch" this morning AND voila! The engine freed up fine, the cylinder loosened and ditto the backplate and cylinder head.

The mini-torch came as an accessory with my Weller soldering torch. At no point did I apply force to free these parts.

Good, Dave. Glad you got it straightened out. I was addressing JP's last comment about his troubles with mushrooming pistons, as in the quote below. So I thought I'd toss in with my similar experiences. It's not a hijack since he's the OP.

JPvelo wrote:Okay, just had the same thing happen last night. Turns out I am mushrooming the piston when I use my reset tool. Have only used it twice and has happened with both pistons.

Rusty:

It's simply not possible for me to rave too much about the usfullness of my Weller butane soldering torch for modeling purposes. Some may balk at the $63 price but it has a miriad of useful purposes besides as a soldering tool.

I have the same problem rusty. Lite taps to nothing but a good enough wallop to reset the socket deforms the piston. Anyone who has used a reset tool successfully feel free to chime in.

Maybe we need to whack on it with one of Dave's soldering tools.
Just kidding, Dave.

Rusty:

You R a funny guy!

By no means to I subscribe the idea that mangling something is a good way to "fix" a problem.

Its got to be the tool, the one I have has a raised center so only the center of the piston rests in the cradle.
I use an 8oz ball-peen and tap it smartly 4 or 5 times. Done 10 or 12 so far with no problems.

JPvelo wrote:I have the same problem rusty. Lite taps to nothing but a good enough wallop to reset the socket deforms the piston. Anyone who has used a reset tool successfully feel free to chime in.

This can happen if your anvil is not sitting on a SOLID surface. The surface should be hard and substantial like a large vise or patio block...wood is not good enough. The problem stems from the hammer force being transmitted through the piston and absorbed by a softer surface. A hard surface will make the force stay at the socket.

Not saying that this is your problem, but it MIGHT be your problem.

George

I've freed a whole bunch of Cox engines that were stuck/frozen in my many years of enjoying them.

The curse may fall upon me but I've never damaged a piston or bore using Hoppe's and mild heat but the BIG trick is PATIENCE in liberal amounts. Rome wasn't built in a day nor was a stuck/frozen Cox freed in a minute.

Frustration is very often your largest enemy. It will cause you to do unreasonable things and damage valueable parts.

gcb wrote:

JPvelo wrote:I have the same problem rusty. Lite taps to nothing but a good enough wallop to reset the socket deforms the piston. Anyone who has used a reset tool successfully feel free to chime in.

This can happen if your anvil is not sitting on a SOLID surface. The surface should be hard and substantial like a large vise or patio block...wood is not good enough. The problem stems from the hammer force being transmitted through the piston and absorbed by a softer surface. A hard surface will make the force stay at the socket.

Not saying that this is your problem, but it MIGHT be your problem.

George

Ditto to what George said. I was suffering about a 20% failure rate doing this on my tool box or small vise. When I moved it to a larger, more solid and stable surface I have been enjoying a 100% success rate. I am certain luck has something to do with it but the numbers did get better.

Good luck,

Bob