Got some Fox .35's that were stored in an area that sustained some water damage and the pistons have rusted in the sleeves at the exhaust opening.

Anyone dealt with this before? Getting replacement piston/liners is easy, but I need to be able to get the old ones out first.

Muriatic acid would dissolve the rust, but would probably attack the exhaust port more than the rust, so I'm hesitant to try that for the first attempt.

I suggest the crock pot and antifreeze method.

http://www.rccanada.ca/rccforum/showthread.php?t=38669

You might also look here:
http://www.rcgroups.com/forums/showthread.php?t=81577

The Crock pot method is generally for gummed up engines but most antifreeze formulas have something in it for rust as well.

Robert

i have had luck with project called PB BLASTER.

PRODUCT. MY BAD

The only way I have ever been able to get a P & L out of an engine with a rusted in piston was to cut the rod in two. After you get the P & L out you might try soaking them in CLR. I have used it with good success on lightly rusted tanks and other stuff. The Fox 35 rods are readily available from Fox.

I have never seen a Fox engine that has been used rust. Likely the piston is stuck because of congealed castor oil. The crock pot will work, but usuall soaking it in a bowl of fuel, methanol, or even denatured alcohol for a day or so will also work.

Visible flaky rust in the exhaust port. They were stored in an area of an unoccupied building that experienced extensive water damage due to a pipe leak that went undetected for about 6 months. Everything in the room was covered in mold and mildew. They are indeed rusted and the cases are corroded, but that's only relatively superficial aluminum oxidization.

If you feel that they are beyond your ability to fix, you can always send them back to Fox for repair or replacement.

George

CRC and an overnight soak followed by applying a torch to expand everything a bit.Tap piston top with a hardwood dowel thru the glowplug hole.It might take a few tries..should work

Evapo-rust it works like a charm, soak the engine in it over night. Evapo-rust will take off paint and anodizing along with the rust, but will not damage the Aluminum.

Ralph

Where do you find evapo-rust??

Hothandle

Try Delbert Cromwell
www.delbertcromwell.com

708-293-7750

Ralph

That link returns a "cannot find that address" from my ISP.

Any other way to contact him?

http://www.daubertvci.com/liquids.asp

Daubert Cromwell - its a company

Try the 708 Phone # or Google Evapo-Rust.

Ralph

You can also get it through epay...and at some of the major automotive parts stores. (works great for your auto restoration projects too [8D] )

I was just reviewing some old posts and ran across yours. I'm late to respond I know. I recently bought a used Enya .19 on eBay that looked like new in the photos. When it arrived I found the piston rusted fast to the sleeve and the sleeve rusted and expanded inside the aluminum crankcase. I simply tore down the engine to where i could get at the rusted stuff and heated the cylinder assembly with a propane torch then let it cool hoping I had cracked the rust loose a-bit. I reheat again and the cylinder sleeve and piston began to move as a unit. I kept heating and moving the cylinder liner and it finally slipped out of the crankcase. I then applied heat to the liner and piston assembly and tapped on the piston crown with a small hammer and a short piece of 3/8" hardwood dowel. The piston broke loose. I cleaned up the piston and the outside of the cylinder sleeve with a light wire wheel in my Dremel moto tool. I didn't want to use any abrasives. I then cut a slot in the end of a piece of 1/4" wooden dowel and cut a 1/2" wide strip of 600 wet/dry paper. I folded the strip over on itself with the abrasive sides exposed and slipped it into the slot in the dowel. I then chucked the dowel into my elctric drill motor and lightly honed the cylinder with light machine oil, WD40 should work. I wanted the bore smooth but not down to bare metal. The engine is now assembled and has such good compresion that you almost can't turn the engine over by the prop hub.

I was lucky but it might work for you also.

Bill

EVAP-O-RUST is now available at Harbor Freight for $20.00 a gallon. I picked up another gallon last week.

I have acquired several engines over the years that were rusted to the point that nothing seemed to work at cleaning them up. I put the engines away and forgot about them. Earlier this year I pulled the engines out, disassembled them as much as I could, and soaked them in Evap-O-Rust for 48 hours. ALL OF THE RUST DISAPPEARED. I was able to salvage the engines and get them running quite well.

Ralph

Bought a gallon of the Evap-O-Rust at Harbor Freight and tried it on one of the badly rusted Fox .35's. It worked. The piston is free and the compression seal seems good. This engine will run again. I don't know how long it will last given the micro-pitting, but I was happy just to get it free again so I wouldn't have to cut the rod or something dire like that.

Make sure to use fuel with 100% Castor oil and no synthetic to get the best from this engine. Glad to hear of your good results freeing the piston.

Robert

My homebrew 5% nitro stunt mix winds up at around 28% castor, but I do toss a few ounces of Klotz in bringing the total oil content in the 30% range. Just a few ounces of synthetic per gallon seems to keep the varnish down. My 50 year old Stunt .29 was pretty badly varnished acting erratically. After an hour or so of running with the bit of Klotz mix its piston looks cleaner and its behaving again.

Basically, I'm cloning Fox Super Fuel and adding a few ounces of Klotz on top of that.

When I get the guts and technical confirmation, I'm going to leave my castor girfriend in the dust. Sorry all you old farts. Get your heads out of the 30s and 40s.

Bill

[link=http://vpracingfuels.com/Oils_specialty.asp]Curious that many savvy 2-cycle racers still use Castor.[/link] I wonder why that is? Maybe its because it works?

I've been around this game a long time. Castor is the difference between getting 20 hours out of an engine or 300 hours.

When you receive that technical information, you may not get rid of that castor after all, at least for your iron/steel engines like that Enya.

I'll keep my castor oil, thank you.

George

Edit: Forgot to mention, one of the best ways to lessen rust is to, after your final flight of the day, disconnect the fuel line, connect the booster and start the engine. It will usually start and run a bit as if you primed it. Do this several times until it will not start. This removes the remaining fuel which produces nitric acid (the nitro), and absorbs moisture (the alcohol). This leaves only the lube...which for me is good old protecting castor, plus some clean running synthetic.

If the engine won't be run for a week or more I follow that up with some air tool oil or Rislone. This is especially important if it is a BB engine.

That's just one way, others work also.

Sir, I have an open mind. We've been running cast iron piston rings on steel liners for nearly 100 years. Just sittin' here thinkin'. Mr. Gordon Jennings thinks that there is no need for that dirty, funky stuff in internal combustion engines - save for it's high film strength at high operating temperatures. I wonder if Ferrari runs castor in their Formula One go carts?

Bill