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Engine basics => Engine set up tips => Topic started by: Allen Eshleman on September 16, 2017, 01:37:01 PM

Title: stuck Cox .049 piston
Post by: Allen Eshleman on September 16, 2017, 01:37:01 PM

Hi,

I have a Cox .049 with a stuck piston.  I bought it new about 5 or 6 years ago.  I flew perhaps 2 flights on it.  Probably didn't store it with After Run oil.  I sprayed WD 40 on top of the piston and in the ports an hour or so ago.  No go.  Would heat perhaps do it?

Thanks for your help.

Title: Re: stuck Cox .049 piston
Post by: James Holford on September 16, 2017, 01:40:44 PM

Soak in fuel for a lil while.

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Title: Re: stuck Cox .049 piston
Post by: Target on September 16, 2017, 03:02:08 PM

If the fuel doesn't work to loosen it, I would try acetone with some oil mixed into it.
Heat should also help too.

Title: Re: stuck Cox .049 piston
Post by: James Holford on September 16, 2017, 03:44:32 PM

Also can put in crockpot with antifreeze set on low over night. I hear that works wonders.

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Title: Re: stuck Cox .049 piston
Post by: Allen Eshleman on September 17, 2017, 03:43:12 PM

I would like to crock pot it or heat it but it has a black tank (plastic I think). Should I remove the tank before using heat?

Title: Re: stuck Cox .049 piston
Post by: James Holford on September 17, 2017, 04:37:09 PM

Yep.. or atleast i would

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Title: Re: stuck Cox .049 piston
Post by: Allen Eshleman on September 17, 2017, 08:18:34 PM

I currently have the engine soaking in fuel, with the tank off.     If I need to try the oil plus acetone method, what kind of oil should I use?

Title: Re: stuck Cox .049 piston
Post by: Ron Cribbs on September 17, 2017, 08:37:15 PM

Have a heatgun? Put a prop on it, heat the cylinder and slowly turn it over. There is a whole forum dedicated to Cox engines...

https://www.coxengineforum.com
 

Title: Re: stuck Cox .049 piston
Post by: Target on September 17, 2017, 11:14:38 PM

Quote from: Allen Eshleman on September 17, 2017, 08:18:34 PM

I currently have the engine soaking in fuel, with the tank off.     If I need to try the oil plus acetone method, what kind of oil should I use?

After run oil,  or penetrating oil is what I'd try. The theory is the acetone will dissolve the goo, and also carries the new oil in with it. Read about that in an old issue of stunt news.
I'd save the anti freeze for last personally.
Good luck.

Title: Re: stuck Cox .049 piston
Post by: Allen Eshleman on September 18, 2017, 05:02:57 AM

Thanks for the help gentlemen.  I soaked it over night in fuel.  That didn't do it in this case. However, I used the heat gun this morning.  It came free.  Another couple of tools in the arsenal. It's great to to have double use for the heat gun and I didn't have to stink up an oven.  That was slick.  Thanks again.  That's the genius of Stunthanger - people helping people.  Who knows?  I might have thrown a good engine in the trash.  I haven't reassembled or run it yet. 

Title: Re: stuck Cox .049 piston
Post by: Gordon Tarbell on September 18, 2017, 06:13:42 AM

When using the acetone and oil trick , blend Acetone with ATF(automatic transmission fluid ) . this is a close second to Aero kroil which on numerous occasions has been lab tested to be the best penetrating fluid. Only difference if memory is correct between the home brew and Aero kroil is the addition of evergreen I think.  Which ATF to use? Good old Dexron II is what is suggested.

Title: Re: stuck Cox .049 piston
Post by: Target on September 18, 2017, 01:06:22 PM

I guess i should have mentioned that it's ATF that i use for my after run oil.....