Hey guys just a quick question, today when i was running my engine in one of the screws on the muffler came loose and the muffler fell off. There was no damage and i cut the engine stright away but since then i could not start the engine again. Any idea why this was? Engine was a OS .46 LA.

phil,

Can't think of any reason reason the muffler falling of should do any bad thing to the engine. If my memory serves me correctly OS supplies cross head screws with the LA, try and get some hex screws if you can.

Beaut flying day today, be good to see ya out at SRCS!


Terry

did you put the pressure line to the tank back on?

It doesn't need the pressure line to start or run. The pressure-drop across the throttle will draw fuel -- you can even fly without the pressure line -- although it will lean out in vertical maneuvers.

Something else is the problem -- we need more symptoms. Is it totally dead, or does it sputter at all? Have you checked the glow plug? Are the head bolts &/or back-plate bolts loose? Did you mess with the mixture screws? Is the carb tight on the crankcase?

The muffler bolts coming loose are a common problem. To fix this remove the bolts. Coat the threads in silicone and then reinstall. Allow 24 hours for the silicone to set up before you run the engine. [8D]

Stating the obvious but is the muffler tight against the exhaust flange? If its loose and leaking it probably wont start at least not easily. Sounds like you had a loose screw or a lot of vibration, might want to just check and make sure everythings tight.

I would change glow plugs, check the needle valve setting, and check to see if the muffler coming off didnt somehow hit the throttle arm and move it out of alignment which will screw up your throttle settings. The little throttle arms on the .46 LAs are CHEAP and flimsy it may have bumped it and moved it. All you have to do is look into the throat with the radio gear on and make sure your throttle butterfly is still in the right position atn idle and full throttle.

Just some outside the box possibilities.

If you are trying to run without the muffler you have insufficient backpressure to keep the plug warm at idle or the mixture is now way off.

As all has said above, It should run.. May need to richen it a little
if you lost/did not replace the muffler.. But I would replace it.. To
many variables with out that back pressure which can cause more
damage than any hp gain... I had a 46/la on my avistar, no gunk
on the threads just made sure the screws where tight... Over 100
flights and all remained on the engine...

If you put the muffler back on and it won't start, I'm guessing that the muffler was loose when the engine was tuned. With the muffler back on and tight, the added pressure would cause your engine to run rich. Try leaning the low speed and see if it will start.

Since the muffler came off, Check the backplate screws as they may have came loose also. If they are loose there will be no crankcase compression to transfer the fuel/air mix to the cylinder.

Need to check all screws from time to time. If loose you can lose parts or have air leaks which will cause intermittent tuning.