Marvel air tool and ATF mixed 50-50 is supposed to be a good, all around ARO.

I was an auto mech for 16 years, When I go to the junk yard and strip parts the inside of an automatic transmission will always be clean, Automatic tranmission fluid is the bomb.

Back when I thought Marvel was it , I'd grab a air-tool I hadn't used in a bit and I'd have bits of marvel oil come out the exhaust of my air-tools. There is a componant in Marvel that evaporates.

I'm glad Mr. tooth decay has brought this problem out in the open to talk about,

We even got most the facts out, good job people !

asterisk---(*)----for engines other than YS

Type F automatic transmission fluid.

DJ,


Why not Dexronâ„¢ I/II/III?

The original was once rumored to be made from whale oil...

Well, I decided to crack open my .61 FX today and guess what......more rust! Surprise! It's a pretty new engine, not sure how old it is cause I bought it for a great price right here on RCU last summer. So I think I will put in an order for some new bearings

Questions:

1. How do you clean up an engine? The rust on the inside, and the burned fuel that accumulates on the outside? I heard XJet make reference to some "antifreeze in a crockpot," can anyone expound?

2. Are some of you guys just pouring Automatic Transmission Fluid in your carbs for after run oil?

Bad Tooth,


Get a set of ceramic stainless steel bearings for this engine, from [link=http://www.rc-bearings.com/catalog/product_info.php?cPath=111_116_125&products_id=831 &osCsid=8ffe0dc5e3317e4dc931c50d3a6beace]Paul at RC-Bearings[/link].

His [link=http://www.rc-bearings.com/catalog/product_info.php?cPath=81_87_98&products_id=671&os Csid=8ffe0dc5e3317e4dc931c50d3a6beace]normal stainless bearings[/link] are not bad either.

you will hear people say that Dextron ATF has friction modifiers to allow smooth shifting of automatic transmissions.

F type does not, do these modifers wreck glo plugs ? my answer for me is, not yet. My Nelsons rest with ATF in them.

You how you buy a quart of ATF in those square plastic bottles? I take a old 409 spray bottle nozzle and spin it onto the top of a quart of ATF and wa-la, after run oil on tap. squert, squert, squert

the additive for posi-traction rear ends had a componant of whale oil, wayyyyyy back. not no mo

Don't know Dar. Just reluctant to recommend something I haven't tried.

Denis

Only 2 ways I have managed to rust out bearings and rust them in a hurry. One not running all the fuel out of the engine at the end of the day and I mean all of it. Two storing a plane in the garage with the nose pointed down with a tuned pipe on the exhaust. The pipe makes a wonderful condenser. Took two engines with about a tea spoon of water in them for me to figure that out.

Denis

I just read this thread for the first time. Man, that is some amazing damage to that engine caused by a small piece of ball bearing. [X(]

As for ARO and MMO, I have used MMO as an after run oil for as long as I can remember. I used to use it straight. Then I started mixing it 50/50 with ATF. Recently, I have mixed it 50/50 with Mobil 1 synthetic motor oil. Each brew has been more slippery than the the previous one. As for drying up, well I just opened a coffee can with an engine in it. I stuck this engine in the can in 1978 and poured in some stright MMO to cover the bearings, cylinder, and crank base. After 30 years it looks like it has evaporate maybe an ounce. And except for the threads on the tip of the crank, I don't see much rust.

That's great and it would have looked the same if you had covered it with kerosene. Great for long term protection ie 30 years.

Yeah. I have another can in my garage somewhere, that has a Kyosho buggy I disassembled into a bunch of parts and covered with MMO also. Around 1984 or 85 I think. It had a lot of steel in it. I wonder what it looks like now....

The OS 50 is famous to injest a rear bearing at about 10 hours. Here is your fix. Get the cheap rc-bearings . The head is fine and the high spots can be sanded off with head gasket removed. The piston ring grove is probably pinched and a new piston is in order and use the old ring. Lightly sand the liner to break in the ring again. Flush the case out good and put back togeather. If the ring is loose in the piston the top of piston can be dressed up a bit and make sure the nicked edge of the top of piston is slightly filed or dressed with sandpaper. Don't sand head or piston to get all the deep pitts out. Just enough to knock down the protruding high spots. The engine will run again.

I would like to try that. The bearings have been ordered. What do you recommend using to sand down the head? Grit? And is there a trick to removing the ring from the old piston without breaking it?

Thanks.

Bad Tooth,


Don't use grit.

I would suggest chucking the head in a lathe and turning it down to reconstruct the combustion chamber to close to its previous shape.
Make sure it rotates concentrically with the sleeve sealing surface.

Do not grind the area of the glow-plug thread, or you would lose about one complete thread, before all the pitting disappears...

It may be best to to make the chamber annulus shaped (instead of 'hemispheric'), with the center protruding into the chamber slightly.
MVVS use this shape and their engines put out great power.

I think you will only need to grind down ~0.2-0.3 mm to get the head and the squish-band smooth.

Grind down the sleeve sealing surface down the same amount as you do the squish-band, to retain squish clearance.

To be honest, I wouldn't bother trying to remove enough material to get rid of the dents in the head.

Just get rid of the high-points (you can even use some small files for that) and put it back together.

We're not talking about an expensive, hi-performance racing engine here, it's just an OS sport engine.

If it really worries you, just buy a new head but I think you'll be surprised at how little difference it's going to make.

At the reynolds numbers we're talking here for the gasflows in the squish-band and combustion bowl, dings small depressions such as those shown in the photos will make virtually no difference and at worst it'll probably cost you 100-200 RPMs compared to a new head.

I wonder how many people that
"never" had rusty bearings ever actually took a good look at them? This is the first time that Ive seen a ball failure. Retainers normally give way and produce identical damage.

When a glow engine goes just put in a box to keep for parts and get a new engine. A replancement engine is too cheap to spend buckets of money buying parts. I had a SO 50SX go lean in flight (fuel line kinked) and it lost glow plug element and nicked the piston. The only way I could see to repair was to find an old engine, maybe a helicopter engine and scavenge parts. The 50 is a good engine but not any stronger than a Thunder Tiger 46 and the Tiger is cheap. My 50 is still in the box and will remain there.

I'm with you, Bob. Sometimes it is just time to buy a new engine.


Ed Cregger

I agree with Buzz, I would not waste the time, you will end up with a suspect engine no matter. There may be other damage to the crankcase bottom end that does not show, yet. The damage to the rod end likley came from something pushing the steel ball into it at high speed, perhaps wedging against the crankcase momentairly or some other part?
I have worked on many engines in my life time, gas, diesel, 2 stroke and 4 stroke small engines and many glow engines. With that type of damage I wouldn't waste my time, unless I just wanted to see if I could do it.
I doubt that it will be as good as it previously was and may not last long. Typical for my projects like this.

How many folks have actually seen engines fail after they've been 'brought back to life'?

somegeek

This is not true about some engines...
As to OS it surely is.


Some manufacturers price the parts, so repair does not pay...

If a P+L set and a couple of bearings cost as much as a new engine; why on earth would it be better to repair?

MVVS, however, can be repaired economically.

Dents in the piston under the squish band or dents in the squish band will result in over compressed trapped gases which will cause detonation. I've fixed a Rossi 40 with equivalent damage from a broken retainer. I did that rather than buy a new one because it's a hobby and making that engine well was a fun exercise.

Denis

I have to agree that some engines, like an OS, are too expensive to repair in a lot of cases due to the high costs of parts.

Some people enjoy tinkering and repairing engines.

Some are very economical to repair. The Evolution engines are very economical, and Dar says that MVVS engines are too. Parts are easy to price and see for yourself.

Some 4 stroke engines are expensive to buy new, and repairs are economical.

Twins and radials would be too expensive to just chuck in trash.

A local flying friend mailed his .50SX up to W8YE to repair the port and piston damage he had inflicted. Jim cleaned up the screwdriver nicks on the liner the best he could, replaced the ring, and didn't replace the piston that was damaged from being cranked when hydrolocked. It ran fine, but had less power than before. Still, the guy was happy since he didn't have the money for parts.