FlyBeetle

My Feedback: (9)

Can anyone tell me if this engine is gone?
Short story: no compression, black piston, sleeve stuck to head cover. Long story - read bellow.

I will try to explain what happened and describe the engine to the best of my abilities.
I posted high quality pictures at [link=http://pg.photos.yahoo.com/ph/[email protected]/album?.dir=/bee5&.src=ph&.tok=phMeo.DBa1d8nlIr]here[/link] (please let me know if the links do not work)

I had this engine mounted on Sig somethin' extra. I was trying to learn how to hover so the plane was not moving much through the air. I had this engine dead stick on me several times, usually about 7 minutes after starting and getting it up in the air. When I would get it refueled and restarted it would seem to run just fine on the ground, but in the air it would "sound" as if it is not revving up to the same rpms as on the ground. It would hover this plane with 12x4 prop at just under half throttle, and it would have power to pull it out vertical. I would hover it for about 10-15 seconds at a time, fall out, make a pass to realign the plane in front of me and at a comfortable altitude and get into hover again.

On my last hovering attempt it got another dead stick, but this time I was not able to get it back on the runway, but rather glided the plane into tall grass and weeds. I found the plane with the main landing gear next to it and a broken prop. When I got it back to the bench, I noticed that the bottom of the plane was wet in fuel. During disassembly I noticed that foam pads around fuel tank, and battery were soaked in fuel. I took out the fuel tank and noticed that the rubber plug was loose [&o] and fuel was leaking around it.

I got the plane home and started repairing the landing gear. I did not get to inspect the engine until about two weeks later. I noticed that when I turned the prop by hand, it did not have much compression and it would make hissing sound. When I took off the muffler I noticed that most of the piston side wall was black, and only the lowest portion was brown, changing to gold color (see photos). I tried to remove the head cover but it did not want to come off easily after removing all the bolts. B.T.W., I noticed that couple of those bolts were not torqued. When I pulled on it a little more it came up with the piston sleeve.
Is this a goner?[&o]

w8ye

My Feedback: (16)

Its toasted alright but it would be nice if we knew what engine it was?

If you use the reply button to answer this, there is a upload files next to the bottom of the edit box. Click on that and then browse your picture file to upload a picture.

FlyBeetle

My Feedback: (9)

It is (was) O.S. 50 SX.

Here is one of the photos. Were there any problems with my link? I did not want to post photos here dirrectly because of their large size.

Is there anything that I can still do with this engine other than scavenging carb, needle valve etc. and using the rest as deadweight?
Can I try to replace sleeve and piston/ ring or is it not worth it?

TLH101

My Feedback: (90)

Put it in a crockpot and clean it so you can tell for sure what it really looks like. Do a search for one of several threads on crockpot cleaning methods.
It appears that most of the black "gunk" is castor residue. If that's case you should be able to get it running just fine. This why you should always use castorblend fuel, it helps prevent damage when you overheat a motor. A new piston & sleeve at most, or if it is a ringed motor, maybe just a ring & sleeve. Maybe just a good cleaning will do the job.

FlyBeetle

My Feedback: (9)

I found a post that described taking apart the engine, removing all rubber parts and soaking it in hot antifreeze for several hours.
Sounds like something I will try this weekend, but I have some more questions:

How will I separate sleeve from head cover?
Do I need to make note of orientation of any parts at dis-assembly? I have never taken apart an engine.

Do you think that it got toasted due to leaking tank? - (could that lean out the mixture in air?)
Do you think it was dying in the air due to overheating (seems like it usually worked for six to seven minutes and than quitting), or was it just due to lack of fuel due to low pressure in tank?

Glen Wearden

An engine can give the impression that it's happy, initially in the flight, even though it may be running too lean, and if the fuel does not have enough oil. After a while, it heats up and then dies. Repeating this process will cook it. Combine this with a possible loose head, and the process magnifies. It may have been over propped for the type of flying you were doing, and that can also cause excessive heat. While it might seem obvious that the leaking tank could be the cause, this probably wouldn't cause overheating, the run would probably be erratic because of reduced pressure, but the engine shouldn't overheat. Lots of possibilities. Glen

w8ye

My Feedback: (16)

The sleeve will fall away from the head if you heat it up in the oven 275 degrees for 20 min.

The sleeve has a certain orientation. there is a little notch in the top flange that fits over a tiny pin in the top of the crankcase.

There is a pin in the ring groove that the ring gap goes on both sides of. This usually goes to the left rear corner.

The rod goes in a certain way. Scratch a light "X" on the back before dissassembly.

You will need to put bearings in the engine also as well as a ring.

Glen Wearden

Just thought of something else. The tank could cause a lean run after a while, but I think you'd really know it. When they go lean in the air, they can really scream, and you can definitely tell it. I've been scoffed at before, but I run fuel with 22% oil, 1/2 castor and 1/2 synthetic. Yes, my planes get dirty, but I've never cooked and engine, and I've had some lean runs, especially with control line using OS LA's. When the engine goes lean in CL, all you can do is fly it out and hope for the best. Luv that castor!! Glen

FlyBeetle

My Feedback: (9)

I was using Cool Power 15% with 18% oil (I think, the label has faded so I can't tell for sure). I had this engine checked by couple fo guys at our field and they did not think it was too lean. It was spitting out some oil residue out of the muffler.
Could the head bolts lose their torque by temperature cycling? Would it give me any indications if they were loose?

I think I will wait with the dissassembly untill I get myself a dedicated pot and make sure that my wife will not be home as I am cooking my engine in her kitchen.

FlyBeetle

My Feedback: (9)

This is my first post and I was very surprised by how quickly I got some helpful replies. THANK YOU GUYS.
As far as engine leaning out during flight I do not think it ever happened - it sounded more as if it was underpowered. Sounded like it was running at lower rpm than on the ground. Plus I was not really running it open throttle, but rather at about half throttle, hovering (attempting ). I realize that it probably gets less airflow than in during normal flight, but can hovering overheat an uncovered engine?

Harry Lagman

There is no doubt that a loose plug in the tank can cause leaning out in flight.

When you fuel the model up and start the engine, fuel pressure is maintained because even though the plug is leaking, it's fuel that is leaking out slowly, because the air gap in the tank is at the top, away from the plug. Once the engine uses fuel or in your case, you go into a hover sequence, what was once a small flow of fuel seeping out of the plug becomes lots of air as the "air bubble" in the tank is now right where the plug is. Fuel pressure can then drop noticeably, leading to a leaning out condition.

FlyBeetle

My Feedback: (9)

Note about leaning out due to leaky tank makes sense. It will be my lesson to check tanks better. I remember that when I was learning how to fly, my instructor told me to always check the tank for leaks. I know that I did that when I build this plane, but it was about two years ago and it looks like the rubber has deteriorated some. I also remember one of the guys at our field tell me to check the tank, and I was to lazy to take tank out of the plane so I just squeezed the exhaust line shut, and blew air into the fuel line. I thought that I could reach a pressure at which I could not blow any more air into the tank.

Well, next time I will take the tank and put it under water and test it properly.

I have pulled on the head a little harder and the sleeve pulled out of the case. Piston ring is looks like it has a missing section about (30 degrees around). In the best case scenario, what parts would I have to replace? Piston ring, sleeve, anything else?

FlyBeetle

My Feedback: (9)

I remember reading a post with someone stating that they have put OS 50 SX engine on I want to say U can do 46 or funtana, and had compared it side by side to another plane just like it with a OS 50 SX/H. They claimed that heli engine showed significantly more power in hover. Would that make sense?

I tried to search for that post, but I am not very good with search yet. I either get hundreds of results (many irrelevant) or none at all.

N1EDM

My Feedback: (2)

Flybeetle, it looks like you might have also been running the engine too rich...

Remember to get a new gasket set for the engine, and possibly an O-ring for the carb-to-engine seal, if it's not included. When you reassemble the engine, you can lube the parts with after-run oil to help them fit back together better.

Also, if you've gurned the heads on any screws, another screw set would be a cheap addition to the parts.

Hope that this helps,

Bob

N1EDM

My Feedback: (2)

I was just looking at your photos again (yes, the link worked fine) and was wondering why only the head is so covered in oil. That could have been because of the two loose screws you found in the head - losing compression, and raw fuel/castor running down the sides of the engine, making a mess.

As far as missing part of the ring, that's odd. It could have been spit out the exhaust stack, or small pieces could have been trapped inside the engine. Look for gouges on the piston and cylinder, and see if there are any metal pieces in the bearings...

Bob

Hobbsy

My Feedback: (102)

It looks like there is a piece of metal laying in the front transfer port, maybe part of the ring.

w8ye

My Feedback: (16)

Yes, the sleeve was obviously twisted in the case as it was pulled out. It most likely caught the ring in a port, breaking the ring and burring the port.

Probably most of the damage to the engine was done at the time the head was raised?

At this point and considering the damage done at disassembly, I would recommend a very experienced engine person to get this engine going again. Possibly even sending it back to hobby services?

Enjoy,

Jim