Author Topic: FP-40 dis-assembly (Read 1686 times)

Allan Perret · « **on:** November 10, 2014, 08:24:31 AM »

Have 2 I'm trying to take apart and clean up.
Got the sleeve out but con-rod is stuck on wrist pin and will not slide AST to come off the crank pin.
Soaked with liquid wrench over nite but still stuck. Any tricks for this ?

Dave_Trible · « **Reply #1 on:** November 10, 2014, 09:25:31 AM »

Allan if you'll scroll down a page or two here you'll see a thread I had going on this problem with the same engine. Some heat was the final answer.

Dave

Allan Perret · « **Reply #2 on:** November 10, 2014, 11:34:03 AM »

Quote from: Dave_Trible on November 10, 2014, 09:25:31 AM

Allan if you'll scroll down a page or two here you'll see a thread I had going on this problem with the same engine. Some heat was the final answer.

Dave

Went back and read that thread. About the soaking in fuel, what component of the fuel is helping with the un-sticking. Just wondering if it makes any difference on the nitro content, as I have several to choose from. I did try a little heat, but sounds like maybe not enough.

Bill Little · « **Reply #3 on:** November 10, 2014, 11:50:51 AM »

Hi Allan,

I suspect the methanol is helping to break down the partially evaporated/hardened castor oil that has stuck the rod on the pin.

Personally I use a Micro Torch (Radio Shack) powered by Butane to point at the rod/pin junction. This liquefies the old oil and you can pry the rod then. I modify a hex key to make a pry bar that will fit in the opening.

BIG Bear
RNMM/AMM

Dave_Trible · « **Reply #4 on:** November 10, 2014, 06:08:18 PM »

Quote from: Allan Perret on November 10, 2014, 11:34:03 AM

Went back and read that thread. About the soaking in fuel, what component of the fuel is helping with the un-sticking. Just wondering if it makes any difference on the nitro content, as I have several to choose from. I did try a little heat, but sounds like maybe not enough.

Allan it wasn't me using the fuel though I'm sure it would work. I use laquer thinner for the soaking. Most times it works after soaking over night but in this case it took the heat from heat gun both to get the sleeve out then the wrist pin loose.

Dave

RknRusty · « **Reply #5 on:** November 10, 2014, 09:25:56 PM »

From what I've learned, any old Fox that's been sitting around should be checked for the wrist pin to be stuck to the rod. It might crank like that but will quickly egg out the holes in the piston. I secured the engine upside down and filled the piston with liquid wrench. The next day I heated it with a heat gun till the oil smoked and used an allen key to work it back and forth. It took some effort to finally free it. Take care not to chip the piston skirt (I don't recall how I know that). But it slides free and runs great now. I learned all about that from a Stunthangar member.
Rusty

Dave_Trible · « **Reply #6 on:** November 11, 2014, 07:23:36 AM »

Quote from: RknRusty on November 10, 2014, 09:25:56 PM

From what I've learned, any old Fox that's been sitting around should be checked for the wrist pin to be stuck to the rod. It might crank like that but will quickly egg out the holes in the piston. I secured the engine upside down and filled the piston with liquid wrench. The next day I heated it with a heat gun till the oil smoked and used an allen key to work it back and forth. It took some effort to finally free it. Take care not to chip the piston skirt (I don't recall how I know that). But it slides free and runs great now. I learned all about that from a Stunthangar member.
Rusty

Indeed! After more than a decade I got a number of engines back out of my Dads hobby stuff including a Fox I used at the 70' Nats. The engine seemed a little stiff but I never thought about a stuck wrist pin so I put the engine on the test stand and fired it up. It started on one flip and sounded great but in less than a minute it began shaking like mad and 'melted down ' on the bench, finally grinding to a halt. Between the stuck pin and fuel corrosion due to age the engine was doomed. If I'd have thought to tear the thing down before I ran it .... Well now I do just that to most every engine I aquire to go into my stockpile.

Dave

RknRusty · « **Reply #7 on:** November 11, 2014, 08:03:11 AM »

There is another re-assembly tidbit that I learned here, and is important to preserving the engine. After installing the piston, crank and liner, feel how free it turns. Then with the glow plug removed, recheck that feel repeatedly while installing and cross tightening the head screws in very small increments. Same goes for the backplate screws, as it's very easy to distort the Fox case. I check it like that when I'm mounting an engine to the airframe too. That's why some people here recommend thin crush pads between the beam and mounting tabs. I suppose you have to treat a Fox like it's made of eggshells, but for all that they sure make fun sport flying engines.
Rusty

Allan Perret · « **Reply #8 on:** November 11, 2014, 09:45:28 AM »

Thanks for all the advice. Got them both unstuck this AM. The heat trick with Allen wrench as a pry bar did the trick. I used a Monokote heat gun directed at underside of piston, after about 90 sec of heat I could smell the castor and figured it was ready. They both popped right off, heavy leather gloves required. I am long past using FP40's myself, but these will make for good hand downs for beginners and sport flyers.

Allan Perret · « **Reply #9 on:** November 13, 2014, 09:50:12 AM »

Cant believe I did this, but after all the effort to get the wrist pins un-stuck, I let one of the sleeves roll off the workbench and hit the floor. Must be egg shaped now because it wont go into case and the piston will not go up into sleeve past the lowest port. Any tricks for salvaging this, new P&L not available..

Gerald Arana · « **Reply #10 on:** November 13, 2014, 10:29:15 AM »

I had a similar thing happen to me. I pitched the engine and got another one off Da Bay.

Good luck, Jerry

PS: Some of those Chinese clones have an ABC P/L that will fit.

Bill Little · « **Reply #11 on:** November 13, 2014, 11:43:28 AM »

Hi Allan,

Check with Randy Smith, he often has the odd tid bit, new and some times "used". I know he had some true ABC sleeve/piston sets made and might have a set of stock parts left over.

BIG Bear
RNMM/AMM

Author Topic: FP-40 dis-assembly (Read 1686 times)

Allan Perret

FP-40 dis-assembly

Dave_Trible

Re: FP-40 dis-assembly

Allan Perret

Re: FP-40 dis-assembly

Bill Little

Re: FP-40 dis-assembly

Dave_Trible

Re: FP-40 dis-assembly

RknRusty

Re: FP-40 dis-assembly

Dave_Trible

Re: FP-40 dis-assembly

RknRusty

Re: FP-40 dis-assembly

Allan Perret

Re: FP-40 dis-assembly

Allan Perret

Re: FP-40 dis-assembly

Gerald Arana

Re: FP-40 dis-assembly

Bill Little

Re: FP-40 dis-assembly