Author Topic: Foster 29 front intake - ringed piston - ring stuck? (Read 1444 times)

Dennis Toth · « **on:** April 19, 2019, 07:05:33 PM »

Guys,
I got a couple Foster engines off eBay, one is a lapped unit and feels great. The second, which I think is a 29, has a ringed piston. This engine turns freely but has no compression. I'm thinking that the engine sat for a long time with the piston at top dead center and the rings are kinda stuck in the groves. I'm thinking that I might be able to use a heat gun blowing into the exhaust to warm the piston and loosen the castor and release the rings. Anyone have any experience unsticking rings?

Best, DennisT

BillP · « **Reply #1 on:** April 19, 2019, 08:04:32 PM »

Over night with antifreeze (I use it straight) in a crock pot on low temp. At a minimum take the plug out. Pull the engine after a couple hours and gently rock the crank to help get it free. Let it cool before putting back in the pot to help cycle expansion/contraction. I've cooked hard stuck ones for days before they loosened up.

bob whitney · « **Reply #2 on:** April 19, 2019, 08:54:27 PM »

Put some Dawn power dissolver in a small cup. heat the piston until hot to the touch, drop in the dawn .let sit a couple of minutes try working it around .do it three or 4 times and pretty sure it will free up /do not leave in over night and once done clean good with reg soap Rad

BillP · « **Reply #3 on:** April 20, 2019, 11:28:02 AM »

I think the the Dawn grease dissolver stuff was discontinued a few yrs ago. I used it a few times way back but it didn't compete with the crockpot method for blackened castor. Also, there is no need to rinse the antifreeze for corrosion after pulling out of the crockpot if you use it straight. For a test I cooked a Fox 40BB and left it on my bench without wiping or rinsing...that was 25+ yrs ago and can't remember how long I left it but if memory is right it was over a month. I took it apart and the bearings and all surfaces that could rust or corrode were still like new. I use cheapest walmark stuff in the crockpot. I also tested engines in cold antifreeze and it did nothing...it has to have heat to work.

Brett Buck · « **Reply #4 on:** April 20, 2019, 11:54:12 AM »

Quote from: Dennis Toth on April 19, 2019, 07:05:33 PM

Guys,
I got a couple Foster engines off eBay, one is a lapped unit and feels great. The second, which I think is a 29, has a ringed piston. This engine turns freely but has no compression. I'm thinking that the engine sat for a long time with the piston at top dead center and the rings are kinda stuck in the groves. I'm thinking that I might be able to use a heat gun blowing into the exhaust to warm the piston and loosen the castor and release the rings. Anyone have any experience unsticking rings?

Best, DennisT

I wouldn't use a heat gun, I would use the oven on the lowest setting, or a food dehydrator on a high setting, maybe 150-180 degrees. , then flood it with the lightest machine oil you can find, like Singer Sewing machine oil, maybe several times. It's worth a try because getting the engine apart and the ring apart, then back on, greatly increases the chance of damage.

DO NOT use oven cleaner (Dawn or otherwise), if you can't get it with heat and oil, crock pot is the next step, short of disassembly.

Brett

FLOYD CARTER · « **Reply #5 on:** April 20, 2019, 01:29:37 PM »

Not really a good idea to take apart a ringed engine. However, I've watched the speed guys do this several times a day, in-between flights, even. But if you have the piston out, you can quickly see if the rings are stuck. And getting them loose is pretty easy with the piston out. If the rings are not pinned, they will be in a different position when put back. Might take a couple runs to get them seated again.

Dennis Toth · « **Reply #6 on:** April 20, 2019, 02:23:03 PM »

I haven't taken the engine apart, I tried to warm it up the piston through the exhaust port with the heat gun and it did not loosen the rings. The engine turns over freely just has more base compression then head compression. It feels like there is ring drag as you turn it over but no seal, very strange. I put a light down into the plug hole and can see the top of the piston, no holes in it. Looking in the exhaust port you can see two rings. I have numerous other ringed engines even my Atwood's with 1/64" ring gaps have compression. I have it soaking in WD40 with the piston at bottom, will see if they pop out. Besides being stuck in the piston ring groove I can't think of any reason why they aren't holding some compression. Any ideas?

Best, DennisT

Brett Buck · « **Reply #7 on:** April 20, 2019, 02:47:45 PM »

Quote from: Dennis Toth on April 20, 2019, 02:23:03 PM

I have it soaking in WD40 with the piston at bottom, will see if they pop out. Besides being stuck in the piston ring groove I can't think of any reason why they aren't holding some compression. Any ideas?

Worn out, or lost tension? Generalized, non-specific evil? Ringed engines are always a crapshoot, this is a classic example of why.

Brett

FLOYD CARTER · « **Reply #8 on:** April 21, 2019, 10:17:33 AM »

All the more reason to take it apart and examine the rings and cylinder bore for scratches.

Las minute thought: If this is a REMCO Forster reproduction, maybe it never had any compression.

Dennis Toth · « **Reply #9 on:** April 21, 2019, 12:49:37 PM »

OK, found it. Someone must have taken this engine apart and didn't put any gaskets back in when they assembled it. Both the head gasket and front case gaskets are missing. Once I added some fuel into the exhaust and put a prop on it and started flipping it started leaking around the head. On the case it seemed like there was excess movement of the shaft. The other Foster 35 I have has no significant movement because there is a circ clip on the shaft that stops movement. Reading some of the reviews on these engines describes how Foster included this clip to prevent the shaft from rubbing on the back of the case. The one on the 29 seemed not to be stopping the rearward movement. Again no gasket. The gasket moves the front of the case out just enough to make the circ clip whole the shaft out from the back of the case.

Now need to find a gasket set?

Best, DennisT

FLOYD CARTER · « **Reply #10 on:** April 21, 2019, 06:21:05 PM »

I have made my own head gaskets, and crankcase gaskets, too. Search this forum and you might find some help on that.

I just checked. MECOA carries parts for Forster 29, 35. They list gasket sets for many Forster engines.

Dennis Toth · « **Reply #11 on:** April 22, 2019, 09:02:30 AM »

Thanks Floyd, I will check them out.

Best, DennisT

John Eyer · « **Reply #12 on:** April 23, 2019, 10:58:51 AM »

I made a head gasket for my Forster 29 rear intake sparkie by notching the 6 cylinder screw locations on a Fox 35 head gasket with a Dremel 1/8 carbide burr. Not pretty but works. A Fox 29 head gasket probably would have been better but did not have one.
John

Jim Kraft · « **Reply #13 on:** April 23, 2019, 07:25:08 PM »

Head gasket material is getting hard to find. I use to have a large sheet of the black asbestos gasket material. The last few years I have used Perfect gasket material with good success. It is a pale green color, but works fine. Not quite as tough as the old black stuff though. Regular gasket material will leak in a short time.

Steve Helmick · « **Reply #14 on:** April 27, 2019, 07:21:37 PM »

Use an aluminum or copper head gasket from an engine with a similar bore. It's almost shocking how the bore sizes are so standardized, especially in metric engines. A crankcase gasket could be made from almost anything, from postcards to scraps of aluminum furnace ducting. The tricky part is estimating the proper thickness when compressed. $:-\$ Steve

Peter in Fairfax, VA · « **Reply #15 on:** April 28, 2019, 05:44:15 PM »

A personal favorite for backplate / crankcase gaskets is brown paper from a sturdy grocery bag, cut with a X-Acto.

Dennis Moritz · « **Reply #16 on:** May 02, 2019, 12:18:37 AM »

Is there an issue with using WD 40 as a penetrating oil to help unstick engines? No one mentioned it. I’ve been crock potting a number engines with straight antifreeze. Pulling them out hot, spraying WD through ports and glow plug hole, freed most up right away. I then oiled with air tool oil. Engines look good flip good. Any thoughts about this method?

Sent from my iPhone using Tapatalk

Dennis Toth · « **Reply #17 on:** May 02, 2019, 12:13:42 PM »

Dennis,
I have used the WD40 after applying heat from a heat gun and it works great. I heat the engine evenly and then spray in the WD down the plug and into the venturi. I let it sit a minute, put on a prop and it usually breaks free. If not I add more heat and try again. Once free I put a few drops of fuel in the exhaust and venturi and turn the engine over several times.

Best, DennisT

BillP · « **Reply #18 on:** May 02, 2019, 02:36:43 PM »

Nothing is wrong with wd40 but I question how much it has to do with unlocking an engine. I think heat does 95% of the work by softening the petroleum products and antifreeze agitates it loose. I had a batch of engines stored several yrs with heavy doses of Marvel Mystery tool oil. It locked them up with a hard substance like what a bowling ball is made of. A couple days in the crock pot worked without forcing anything. I tried the "miracle cleaner of the day" others were raving about and it didn't touch them. I run 20-29% all castor so tend to have it worse than the synthetic flyers.

Jim Kraft · « **Reply #19 on:** May 02, 2019, 02:49:24 PM »

WD 40 used in small amounts is OK. The R/C guys use to run their engines on it at the end of the day to clean out the nitro and oil. After a short time is cakes on the piston and is hard to get off. I use PB Blaster to free engines and clean castor of dope finishes. Works great. WD 40 has many uses, but I keep it out of my engines as I have seen what it can do.

Dave_Trible · « **Reply #20 on:** May 02, 2019, 03:15:37 PM »

I've had pretty good luck soaking the engines in lacquer thinner overnight. Take it apart as much as is possible to allow the thinner to get to the stuck parts. On stubborn cases a little heat usually finishes the job. Just had to get a K&B .61 rod, shaft and bearings apart and replaced. Brand new engine stuck with the factory lube. Had to expand the case with heat to get the bearings out. Mecoa had the new bearings.

Dave

FLOYD CARTER · « **Reply #21 on:** May 02, 2019, 03:27:35 PM »

Freeing up stuck engines has been a hot topic here for as long as I remember. Seems like all the suggestions will work, and some just a little better than others. So, it doesn't seem to be a big issue, or a tough nut to crack.

Brett Buck · « **Reply #22 on:** May 03, 2019, 10:12:51 AM »

Quote from: BillP on May 02, 2019, 02:36:43 PM

Nothing is wrong with wd40 but I question how much it has to do with unlocking an engine. I think heat does 95% of the work by softening the petroleum products and antifreeze agitates it loose.

Bingo. Antifreeze is used because it transfers the heat better than air, and it's for sure not going to cause any other sort of corrosion. And it's water-soluble, so easy to remove. The crock-pot/antifreeze system was a remarkable breakthrough in cleaning engines in all respects, it's a miracle. All the other half-assed systems like oven cleaner and dishwasher detergent always had potentially dangerous side-effects, they are simply obsolete.

It is, however, generally not necessary to just get engines loosened up enough to take apart. Plain old heat (oven at 175 degrees) is almost always sufficient and takes no clean-out.

Brett

Dennis Toth · « **Reply #23 on:** May 04, 2019, 03:20:30 PM »

Gasket set arrived from MECOA. That did it. Nice compression, feels good.

Best, DennisT

FLOYD CARTER · « **Reply #24 on:** May 05, 2019, 10:30:52 AM »

Heat from an oven, or hair dryer will soften the hardened goo. But it will just harden again when the engine is cooled. You have to flush out the old oil. I suppose heat+ solvent might be the quickest method.