I have a O.S. Fxi 46 engine that I think may be coming to it's end. My question is am I right or should I try something else?

This engine is around 4 years old with well over 100 flights on it, maybe closer to 175-200. I am just starting to learn the tuning of engines and last year a experienced pilot stopped by and said he could adjust my engine better for me, and he did.

Before he made any adjustments I always had a "smoke" trail from the exhaust and after he made the adjustments I did not see the trail anymore, but the plane did speed up in flight alot. I quess I have made around 50 or so flights with the engine set this way and then the engine would start to cut out after 10 minutes of flight time and then just dead stick, I use to get a good twenty minute flight before.

Now after ten minutes of flight it just dies, period. If I refuel it back up and make a second flight it will run great and then die every time after ten minutes of flight. The fuel system checks out fine and I am thinking that the engine must just be getting to the heated point at ten minutes that will cause it to die and the time it takes me to refuel it the engine has time to cool back down.

Now I am starting to learn to adjust the engine I have adjusted it a little richer, real rich, a little leaner, and real lean, but it does not seem to matter and it will run great until ten minutes and then cut out and die.

ANY IDEAS. My idea is the engine was run to lean and I have messed something up and it is just time to buy another one.

I'm afraid that your "friend" ruined your motor for you. Too many people seem to think they need to get every last RPM out of a motor. My club President is that way. A nice smoke trail is IMO a good thing and means that you have sufficient oil NOT being burned up in the engine but acting as a lube. Running on the rich side is important for ALL engines and even more important for ringed engines. I don't recall if yours is ringed or not but I'm sure you have done some damage. Has your compression dropped somewhat too? You could rebuild the engine but it may be more cost effective to replace it especially if you are unfamiliar with engine assembly. You may need a piston/sleeve if an ABC/ABN type engine or a ring/sleeve if a ringed engine. Once the damage is done it is hard to recover without throwing some parts at it. Sorry. []

I agree with Bruce. It's a pretty good chance that you burned up your motor. Running one flight with the motor too lean probably wouldn't hurt it too much, but running 50 flights as you said probably ruined your motor. Bruce was right that running the motor a bit rich, with a smoke trail, will keep that motor running for a very long time. I have an old OS 40 that is on my original trainer and it's got 600+ flights on it and it still runs like a champ, and its' always been run a little rich. A lot of pilots like to squeeze out those extra few hundred RPM's and lean out there motor when they fly, and they also will be replacing motors at a regular interval too.

I know that it's like closing the door after the horse got out, but a little advice in that I don't ever let somebody adjust my motor unless I ask them to help me. And even then I will ask them what they just did and why. Unfortunately every flying field has that type of person that roams the pits "helping" people without asking them. These guys are always trying impress everybody with how much they know and want to have everything done their way. They should be avoided for the very reason as to what they did to your motor. We have one at our field and I've told him in no uncertain terms that if he ever touched any of my stuff he'd be buying, period!!

Ken

Thanks for the info., but I assumed the guy was helping me at the time, which I am sure he was trying to do. However at that time I was really to new to know the differance and just went along. Well at least I am learning from it and now I know how NOT TO run the engine. Besides I guess now I can try another engine.

It might be worth it to take a look at ur fuel line and tank to make sure there isn't something wrong that's inhibiting fuel flow after the tank gets to a certian level.
-John

Striderjg, thinks for the info. and I am ready to take all the info. I can get however I already replaced everything but the fuel tank itself. The reason I did this was because I checked all of it and I could not see anything that looked wrong to me so I just replace it to make sure. Besides I will need some spare fuel tank parts sooner or latter anyway.

I agree with striderjg. If you were running rich then the motor should not heat up enough to die no matter the damage. It is probably a coincidence that after tuneup the engine dies 10 minutes into a flight. see if there is fuel in the tank after 10 minutes. let it cool for awhile then try to restart it and fly a few minutes. my guess is that you have a small airleak in the fuel line or tubingeither inside the tank or outside. see if airbubbles are traveling in the fuel line. If they are they can lean an engine out in flight and overheat it and kill it too. If the leak is on the inside then it might not leak air until you burn enough fuel to get the fuel level so it is not covering the leaking hole. glow fuel causes brass tubing to go bad very slowly and also fuel tubing goes bad with age fuel and vibration. It is a good thing to check the fuel system on older aircraft. I have had to redo a few after about 2 years time. It doesn't cost anything to check it. If the leak is inside the tank, you can't check for a leak by seeing if the tank holds pressure because the leak is inside of the two ways for air or fuel to get in or out of the tank

If you think you might have a hole in the tubing then just replace it. A few cents worth of tubing isn't worth the effort to check.

One time I had an engine that ran fine, then one day the flight times were half of what I was getting previously, resulting in deadsticks. Replaced all the tubing, including the one between the carb/needle, but the problem continued until I replaced the stopper in the tank.

I've not worn out an engine yet, but the one that is close takes a lot of time to prime, ie with a starter until the fuel reaches the carb.

Hi Brooke, Just to add my 2 cents worth,I had a Irvine 53 and it would run fine then get slower and slower and then stop mid flight.
I was discussing this with some experts who asked what fuel I was running.
I normally run 10% nitro and 20% synthetic oil[coolpower] and 70% methanol in all my planes.
This however was the problem.In certain motors Irvines especially they have very fine tolerences between the head and piston and they tend to heat up quickly with the nitro in the fuel.
I thought my Irvine was buggered until I was told to try Castor and methanol mixed at 4 - 1 or 200mls of castor to 800mls of methanol, no nitro.
I did this and now my Irvine runs like a dream.
This might not be your answer but it is worth a try and you never know you might just be able to keep your motor going for a few more years after all.
Best of luck..
Joe.

try the tank check to make sure all lines are good for sure, if your motor is to lean look in the handbook and return the low speed needle to its origonal factory settings then adjust the high speed needle also to the factory settings thats a starting point. also if you have a tachometer its helpfull for adjusting the H.S. needle max RPM then back it off a couple of hundred look for the smoke again after so few flts under 300 there is a chance your motor might be ok if you feel confident take it apart and look for wear if its still running just get it back to where you see some smoke . smoke/fuel out the pipe meens the engine is being cooled as posted above the OS manuel is pretty clear on settings. hope your buddy didnt help you out of a motor then