I have O.S. 46 AX and its working strange, I used less then one gallon of fuel through it including the brake in.
I saw bubbles coming from the gap between the head and the cylinder, I tightened the head but still its like don’t get to the high RPM, the instructor said there is some issue with it.
The head is getting very hot.
It’s pulling the plane I think because of over powering I guess.

Question: What’s the OS warranty would do in this situation?
Is this sound like permanent damage to the engine?

Besides that the tree caught my plane, so MidStar no more, im getting the Four star 40 ARF instead earlier then I thought.
I’m sad for loss of the plane but what I wanted from it is to learn take off and landing with a tail dragger.

Thanks
Alex

Alex, is it running poorly? Engines get hot, so ya, the head is going to be hot . I have never had bubbles, could be castor from to lean of an engine.


Good Luck
Cameron

Its like loosing compression, I closed it but still it doesn’t scream. []

What do you call 'scream'? Did you put a tach on it to see what RPM it's getting? And, with what prop?

You're running too lean. You may have destroyed the cylinder/liner by now.

"could be castor "? Have no idea what that means.

You may have also burned a hole in the piston top.

The prop is 11*7, its just doesnt feel like it got its full potential, i didnt check RPM with instruments.

Does the engine seem to perform well at first then lose power in the air after a very short time? Does the engine feel like is has noticeably less compression after it loses power and you bring it in and check it? Does the compression seem to come back after the engine has cooled? If you answered yes to all of these questions then the piston to cylinder liner fit is shot.

since your using the term engine scream..I'll bet it was running too lean. When you tightened the head was the head hot? Did you use a cross torque pattern to tighten the screws? Or did you just go in a circle?...I wonder if the head is warpped and not seating properly

Now the head is sitting well, it run two flights after i checked and tightend it, but i dont trust it any more.

Is this sound like permanent damage to the engine?

Fuel bubbling from the gap between the crank case and the cylinder head is indicative of head gasket failure. Send the engine in to Hobby Services for warranty and they should make it right for you.

Edit: This is also evidenced by the hot running condition of the engine. The cylinder head gasket is allowing air to leak into the combustion chamber causing the engine to run in an overly lean condition (too much air vs. fuel). This makes the engine very difficult to tune, you are quite fortunate if you've been flying with this engine.

I had a similar problem with a GMS engine. The head gasket was leaking, so I replaced it. I was tuning the engine back in after getting the cylinder head re-sealed when the connecting rod broke. Hobby Services simply sent me a brand new engine.

thanks Ed, thanks everybody,
i'll speak with the hobby service tomorrow.

Alex

I am running my O.S. .46 AX on an 11X6 prop. At peak RPM I am hitting 13,300. I then richen it up to 12, 900 (or maybe just a little bit lower). The only problem I have had with it is once, it two hits of the electric starter to get it to catch. Also, I am running 15% nitromethane with 20% all castor oil. I love the engine.

I have tried 10%, 12%, and 15% nitro with little noticeable difference in performance, just in higher fuel cost. The engine does seem to run hotter with the higher content but thats about all. The last couple of times I needed fuel the LHS only had 12% so thats what I bought but the engine seems just as happy with 10%. [8D]

I have herd that castor seeps out on the head when the engine is run lean. Wouldn't know for sure since i run synthetic.

after break in of my OS46, the head bolts had loosened up a bit, but you shouldn't be *****g the rpm of your new engine until after at least 5- 10 tanks of fuel OS recomends you run it nice and easy and slopy rich not tached out with no adverse vertical manuevers until full break in of the AX.
1 gal is not alot of fuel for this engine 10 tanks @12oz ea.= 120 oz.almost a gallon your engine is about broken in at that point.
after my first gallon I switched to the OS#8 plug mainly because the one provided,the #3 kept coming loose, but I found it ran alot smoother with the cooler plug.
I run coolpower 10%nitro 18%oil in all my engines 2 and 4 stroke.
you might want to ask a expierenced club member to look your engine over for you, someone who will know a burnt piston and cylinder vs.normal wear and tear it might need to be cleaned of some of the fuel deposits and the bolts tightened, the fuel residue can get prety hard when its been cooked while it was leaking,and could prevent the head from seating properly, but its best to have someone who knows what to look for check it out first hand.
my engine runs great and has been a super reliable performer spinning a 11/5 prop.