Cox Engines Forum
You are not logged in! Please login or register.

Logged in members see NO ADVERTISEMENTS!


Varnish seize? Cox_ba12




Varnish seize? Pixel

Log in

I forgot my password

Search
 
 

Display results as :
 


Rechercher Advanced Search

Latest topics
» "Me and Crazy Horse...Our Anniversary"
by Kim Today at 3:23 am

» Project Cox .049 r/c & Citabrian Champion
by balogh Today at 12:55 am

» Original Box for P-51 Bendix Trophy Racer Value
by Wayne Brown Yesterday at 11:09 pm

» Cox P-51 Bendix Trophy Racer
by Wayne Brown Yesterday at 5:39 pm

» thread measurements
by MauricioB Yesterday at 5:33 pm

» Cox Thompson Trophy Winner
by Jerry Yesterday at 5:20 pm

» COX 010 TeeDee with RC carb, courtesy sosam 117
by rdw777 Yesterday at 3:08 pm

» a cheap sport muffler
by robot797 Yesterday at 1:34 pm

» OS 10FSR Carb Needed
by Cougar 429 Yesterday at 1:14 pm

» AP .061 Hornet
by F4D Phantom II Sun Mar 17, 2024 10:01 pm

» dozens of old .049 TeeDee's, Medallions and a few others
by rsv1cox Sun Mar 17, 2024 7:46 pm

» Re-manufactured Enya .06-II for Boats13
by Boats13 Sun Mar 17, 2024 7:32 pm

Cox Engine of The Month
March-2024
balogh's

"COX Budapest" .049 engine



PAST WINNERS
CEF Traveling Engine

Win This Engine!
Gallery


Varnish seize? Empty
Live on Patrol


Varnish seize?

Page 1 of 2 1, 2  Next

Go down

Varnish seize? Empty Varnish seize?

Post  JPvelo Tue Sep 11, 2012 6:33 pm

Was running a #1 cylinder last nite that had alot of varnish buildup on the piston top ( almost black) and on the plug(dark brown). After the run a great deal of varnish was removed from the piston but the fit is now extremely tight. Could that much varnish build up on the walls in one run? Was testing an enlarged Venturi backplate and it did lean way out for about ten seconds. Could I have warped the cylinder? It is tight immeadiatley at the top of the exhaust port.
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1963
Join date : 2011-12-02
Age : 56
Location : Phoenix

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  RknRusty Tue Sep 11, 2012 7:30 pm

JPvelo wrote:Was running a #1 cylinder last nite that had alot of varnish buildup on the piston top ( almost black) and on the plug(dark brown). After the run a great deal of varnish was removed from the piston but the fit is now extremely tight. Could that much varnish build up on the walls in one run? Was testing an enlarged Venturi backplate and it did lean way out for about ten seconds. Could I have warped the cylinder? It is tight immeadiatley at the top of the exhaust port.
The varnish that melted off the top of the piston could have re-deposited on the cylinder wall. If it added to an already varnished cylinder, it might be enough to stiffen it up. Was the plug and head cleaner looking after the run?

If it leaned out long enough to get really hot, I suppose some of the imbedded castor varnish could have expressed out of the cylinder wall. If I understand correctly, it is leaded steel, so it could conceivably hold enough varnish(like bronze absorbs oil) to melt and move out onto the surface of the wall. That's a guess, I'm not a chemist. My son is, but he isn't here to lecture me on the subject.

You didn't remove the cylinder from the crankcase with the exhaust port wrench did you? If not, for future reference, and for anyone reading this, the way to use that tool is to trap it in a vice so it can't deform as you unscrew the cylinder. Otherwise you get a burr on the port edge that makes it stiff until you find and remove the burr.

_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!


My Hot Rock & Blues Playlist
RknRusty
RknRusty
Rest In Peace
Rest In Peace

Posts : 10869
Join date : 2011-08-10
Age : 67
Location : South Carolina, USA

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  Ken Cook Tue Sep 11, 2012 9:13 pm

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
Ken Cook
Ken Cook
Top Poster
Top Poster

Posts : 5408
Join date : 2012-03-27
Location : pennsylvania

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  jsesere Wed Sep 12, 2012 1:21 am

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

Posts : 1606
Join date : 2010-09-05
Location : Salem Oregon

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  John Goddard Wed Sep 12, 2012 2:19 am

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 Mad
John Goddard
John Goddard
Diamond Member
Diamond Member

Posts : 2447
Join date : 2011-11-24
Age : 59
Location : Leyton North East London

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  Ken Cook Wed Sep 12, 2012 3:12 am

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
Ken Cook
Ken Cook
Top Poster
Top Poster

Posts : 5408
Join date : 2012-03-27
Location : pennsylvania

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  JPvelo Wed Sep 12, 2012 9:18 am

Rottenstone? What is it and where do I find it?
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1963
Join date : 2011-12-02
Age : 56
Location : Phoenix

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  Ken Cook Wed Sep 12, 2012 10:16 am

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
Ken Cook
Ken Cook
Top Poster
Top Poster

Posts : 5408
Join date : 2012-03-27
Location : pennsylvania

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  SuperDave Wed Sep 12, 2012 10:53 am

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

Give your engine a good soaking/cleaning then see how it runs after.
SuperDave
SuperDave
Rest In Peace
Rest In Peace

Posts : 3552
Join date : 2011-08-13
Location : Washington (state)

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  gcb Thu Sep 13, 2012 12:35 pm

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
gcb
gcb
Platinum Member
Platinum Member

Posts : 908
Join date : 2011-08-11
Location : Port Ewen, NY

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  Apollo Kenney Thu Sep 13, 2012 11:16 pm

[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
Apollo Kenney
Apollo Kenney
Moderate Poster
Moderate Poster

Posts : 13
Join date : 2012-09-05
Age : 28
Location : Eugene, OR

Back to top Go down

Varnish seize? Empty Solved

Post  JPvelo Fri Sep 14, 2012 1:39 pm

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

Posts : 1963
Join date : 2011-12-02
Age : 56
Location : Phoenix

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  SuperDave Fri Sep 14, 2012 2:35 pm

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. lol!
SuperDave
SuperDave
Rest In Peace
Rest In Peace

Posts : 3552
Join date : 2011-08-13
Location : Washington (state)

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  JPvelo Tue Sep 25, 2012 8:34 am

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
JPvelo
Diamond Member
Diamond Member

Posts : 1963
Join date : 2011-12-02
Age : 56
Location : Phoenix

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  RknRusty Tue Sep 25, 2012 9:07 am

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.

_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!


My Hot Rock & Blues Playlist
RknRusty
RknRusty
Rest In Peace
Rest In Peace

Posts : 10869
Join date : 2011-08-10
Age : 67
Location : South Carolina, USA

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  SuperDave Tue Sep 25, 2012 9:46 am

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
SuperDave
Rest In Peace
Rest In Peace

Posts : 3552
Join date : 2011-08-13
Location : Washington (state)

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  RknRusty Tue Sep 25, 2012 11:22 am

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.

_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!


My Hot Rock & Blues Playlist
RknRusty
RknRusty
Rest In Peace
Rest In Peace

Posts : 10869
Join date : 2011-08-10
Age : 67
Location : South Carolina, USA

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  SuperDave Tue Sep 25, 2012 11:36 am

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.
SuperDave
SuperDave
Rest In Peace
Rest In Peace

Posts : 3552
Join date : 2011-08-13
Location : Washington (state)

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  JPvelo Tue Sep 25, 2012 12:31 pm

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.
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1963
Join date : 2011-12-02
Age : 56
Location : Phoenix

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  RknRusty Tue Sep 25, 2012 3:23 pm

Maybe we need to whack on it with one of Dave's soldering tools.Varnish seize? Laugh-1
Just kidding, Dave.Varnish seize? Icon6

_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!


My Hot Rock & Blues Playlist
RknRusty
RknRusty
Rest In Peace
Rest In Peace

Posts : 10869
Join date : 2011-08-10
Age : 67
Location : South Carolina, USA

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  SuperDave Tue Sep 25, 2012 3:55 pm

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. Mad Sad
SuperDave
SuperDave
Rest In Peace
Rest In Peace

Posts : 3552
Join date : 2011-08-13
Location : Washington (state)

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  crankbndr Tue Sep 25, 2012 3:59 pm

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.
crankbndr
crankbndr
Top Poster
Top Poster

Posts : 3055
Join date : 2011-12-10
Location : Homestead FL

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  gcb Tue Sep 25, 2012 4:32 pm

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
gcb
gcb
Platinum Member
Platinum Member

Posts : 908
Join date : 2011-08-11
Location : Port Ewen, NY

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  SuperDave Tue Sep 25, 2012 4:55 pm

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.
SuperDave
SuperDave
Rest In Peace
Rest In Peace

Posts : 3552
Join date : 2011-08-13
Location : Washington (state)

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  fit90 Tue Sep 25, 2012 7:14 pm

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
fit90
fit90
Diamond Member
Diamond Member

Posts : 1336
Join date : 2011-08-11
Location : Naples, Florida

Back to top Go down

Varnish seize? Empty Re: Varnish seize?

Post  Sponsored content


Sponsored content


Back to top Go down

Page 1 of 2 1, 2  Next

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum